1 00:00:02,480 --> 00:00:07,099 In 1807, maverick Cornish chemist Humphrey Davy 2 00:00:07,099 --> 00:00:10,699 attempted something no-one had dared try before. 3 00:00:11,359 --> 00:00:15,800 He harnessed a newly discovered force, electricity, 4 00:00:15,800 --> 00:00:20,160 to rip apart a caustic chemical called potash. 5 00:00:20,460 --> 00:00:23,000 And he discovered a new element. 6 00:00:26,160 --> 00:00:29,239 Vivid, violent potassium. 7 00:00:32,479 --> 00:00:39,479 Davy had found a new way of cracking open the natural world, to reveal its building blocks. 8 00:00:42,479 --> 00:00:46,479 This is the story of one of the biggest questions there is. 9 00:00:47,479 --> 00:00:50,479 What is everything in our world made of? 10 00:00:53,479 --> 00:00:58,479 The quest to find out would ultimately lead to an extraordinary insight. 11 00:00:58,479 --> 00:01:04,480 that everything from the diversity of nature to the complexity of man 12 00:01:04,480 --> 00:01:08,480 was made from just 92 elements. 13 00:01:12,480 --> 00:01:16,480 I'm Jim Al-Khalili and I've studied physics all my life, 14 00:01:16,480 --> 00:01:20,480 but I couldn't have gained my knowledge of the subatomic world 15 00:01:20,480 --> 00:01:25,480 without the work of the chemists who first unravelled the mysteries of matter. 16 00:01:25,480 --> 00:01:27,480 Brilliant. That was really beautiful. 17 00:01:27,480 --> 00:01:35,420 Finding and understanding the elements would turn out to be one of the greatest detective stories in the history of science. 18 00:01:35,780 --> 00:01:39,400 A staggeringly difficult task that would span centuries. 19 00:01:40,819 --> 00:01:48,560 I'm going to retrace the steps of the chemists who risked their lives to prize secrets from the natural world. 20 00:01:48,760 --> 00:01:52,780 Instantly disfiguring, instant blindness, it's really hideously dangerous. 21 00:01:52,780 --> 00:01:58,219 I'll find out how scientists struggled to crack 22 00:01:58,219 --> 00:02:01,040 one of the most important codes in the universe. 23 00:02:03,920 --> 00:02:07,939 And I'll discover how our fascination with the elements 24 00:02:07,939 --> 00:02:10,639 led to the making of the modern world 25 00:02:10,639 --> 00:02:15,259 and pushed the human race to the edge of destruction. 26 00:02:15,259 --> 00:02:27,800 our compulsion to seek answers at almost any cost and to search for fundamental truths has 27 00:02:27,800 --> 00:02:35,780 powered scientific endeavor and it underpins this story our quest to unravel the mysteries 28 00:02:35,780 --> 00:02:56,419 of the elements it's hard to imagine what it must have been like to look 29 00:02:56,419 --> 00:03:02,240 around and not have a clue what the world is made of not to know what this 30 00:03:02,240 --> 00:03:08,419 contained to be mystified by fire to have no idea that oxygen is essential to 31 00:03:08,419 --> 00:03:15,080 make it burn or the oxygen even existed not to know that hydrogen is a vital 32 00:03:15,080 --> 00:03:24,960 ingredient of the ocean or that sodium and chlorine combine to give it salty taste it's 33 00:03:24,960 --> 00:03:31,120 only in the last 200 years that we've known what an element is it's a substance that can't be 34 00:03:31,120 --> 00:03:40,669 broken down into a simpler one by a chemical reaction the ancient greeks already knew of lead 35 00:03:40,669 --> 00:03:48,909 copper gold silver iron mercury tin but to them these were just metals they were convinced that 36 00:03:48,909 --> 00:03:53,909 the whole world was made of earth, air, fire, and water. 37 00:03:55,069 --> 00:03:56,909 For more than a thousand years, 38 00:03:56,909 --> 00:04:00,849 we had no way of breaking open the natural world, 39 00:04:00,849 --> 00:04:04,810 and no choice but to base our concept of elements 40 00:04:04,810 --> 00:04:06,889 on what was visible around us. 41 00:04:13,060 --> 00:04:17,319 By the 16th century, things were starting to change. 42 00:04:17,319 --> 00:04:21,279 Alchemists began to penetrate the substances around them 43 00:04:21,279 --> 00:04:25,279 in their bid to turn base metals into gold. 44 00:04:25,279 --> 00:04:28,360 They kept secret notes of their experiments 45 00:04:28,360 --> 00:04:31,879 written in mysterious codes and symbols, 46 00:04:31,879 --> 00:04:36,129 and they dreamed of immortality. 47 00:04:36,129 --> 00:04:39,990 From the Far East through Europe to London, 48 00:04:39,990 --> 00:04:42,990 the back streets and cellars were a seething, 49 00:04:42,990 --> 00:04:46,569 bubbling hotbed of alchemical research. 50 00:04:46,569 --> 00:04:57,110 it was an alchemist who first challenged the greek idea that everything was made from earth 51 00:04:57,110 --> 00:05:09,889 fire air and water in a story which begins in baal switzerland it starts with philippus 52 00:05:09,889 --> 00:05:16,490 teofrastus ariolus bombastus von hohenheim who thankfully for me because i'm not saying that 53 00:05:16,490 --> 00:05:26,189 again, adopted the nom de plume Paracelsus. Paracelsus was not just an alchemist trying 54 00:05:26,189 --> 00:05:32,189 to unlock the mysteries of matter. He was also a physician and surgeon, and he wasn't 55 00:05:32,189 --> 00:05:48,410 afraid to challenge the orthodoxy of the day. In 1526, the city of Baal was famous for its 56 00:05:48,410 --> 00:05:54,649 printing, and its most sought-after printer, Frobenius, had just been told by his doctors 57 00:05:54,649 --> 00:05:58,829 that unless he had his leg amputated, he would die. 58 00:06:00,029 --> 00:06:02,870 So Frobenius called for Paracelsus, 59 00:06:03,230 --> 00:06:06,910 who wouldn't accept the medical orthodoxy of the day. 60 00:06:07,870 --> 00:06:11,490 He also wasn't afraid to mix medicine with alchemy, 61 00:06:12,089 --> 00:06:15,350 to concoct new potions and remedies. 62 00:06:17,009 --> 00:06:21,730 He created a cure that not only saved Frobenius' life, 63 00:06:21,730 --> 00:06:25,410 but established Paracelsus as a true radical. 64 00:06:26,350 --> 00:06:28,990 He proposed a groundbreaking new idea, 65 00:06:29,649 --> 00:06:33,310 suggesting that the world was actually made of three elements, 66 00:06:33,990 --> 00:06:36,750 salt, sulphur and mercury. 67 00:06:40,519 --> 00:06:45,959 Paracelsus saw these as the core ingredients to make metals and medicines. 68 00:06:46,839 --> 00:06:48,959 He reckoned salts would heal wounds, 69 00:06:49,699 --> 00:06:51,339 Sulfur was combustible, 70 00:06:51,920 --> 00:06:56,060 and mercury, known then as quicksilver, was fluid and volatile. 71 00:07:00,629 --> 00:07:02,410 Now, mercury is an incredible substance. 72 00:07:02,930 --> 00:07:06,649 It's the only metal that's liquid at room temperature. 73 00:07:07,350 --> 00:07:09,310 It's also remarkably heavy. 74 00:07:09,310 --> 00:07:12,290 I mean, just this small amount here feels very, very heavy, 75 00:07:12,589 --> 00:07:15,370 but I've got a much larger amount here, 76 00:07:15,689 --> 00:07:19,310 and if I try and lift it... 77 00:07:19,310 --> 00:07:23,009 it's not stuck to the table 78 00:07:23,009 --> 00:07:26,610 it's 14 times heavier than water 79 00:07:26,610 --> 00:07:28,370 it's also toxic 80 00:07:28,370 --> 00:07:31,089 so I'm wearing a triple layer of gloves here 81 00:07:31,089 --> 00:07:33,290 because I'm going to do something I've always wanted to do 82 00:07:33,290 --> 00:07:35,629 which is dunk my hand in mercury 83 00:07:35,629 --> 00:07:40,399 it feels very very strange 84 00:07:40,399 --> 00:07:42,160 it's pushing my hand up 85 00:07:42,160 --> 00:07:48,569 it's nothing like any liquid that I know of 86 00:07:48,569 --> 00:07:52,170 it feels very cold as well 87 00:07:52,170 --> 00:07:58,939 even through the three layers of gloves I can feel its coolness and just to give 88 00:07:58,939 --> 00:08:04,680 you an idea of how weird this stuff is I've got a steel bolt here and let's see 89 00:08:04,680 --> 00:08:11,480 what happens if I put it in the mercury mercury is so much denser than steel it 90 00:08:11,480 --> 00:08:24,759 floats mercury silvery and mirror-like it's one of the most beautiful and 91 00:08:24,759 --> 00:08:28,800 and elusive of all the elements. 92 00:08:28,800 --> 00:08:34,779 It's rarely found in its natural form, but heating a red rock, cinnabar, will reveal 93 00:08:34,779 --> 00:08:41,559 molten mercurial lava hidden within. 94 00:08:41,559 --> 00:08:48,139 The phrase mad as a hatter was coined when hat makers who used it suffered from mercury 95 00:08:48,139 --> 00:08:52,710 madness. 96 00:08:52,710 --> 00:08:59,070 In the mines of South America, treasure hunters risked their lives by using toxic mercury 97 00:08:59,070 --> 00:09:03,870 to extract another element, gold. 98 00:09:03,870 --> 00:09:15,019 And floating on mercury gave smooth motion to the revolving light of some Victorian lighthouses. 99 00:09:15,019 --> 00:09:21,220 Paracelsus didn't manage to convince the establishment with his idea of the three elements, 100 00:09:21,220 --> 00:09:24,120 mercury, sulphur and salt. 101 00:09:24,120 --> 00:09:28,320 In fact, he'd enraged them by ignoring their medical texts 102 00:09:28,320 --> 00:09:30,720 and creating alchemical cures. 103 00:09:31,200 --> 00:09:33,519 He was too radical for his time. 104 00:09:34,100 --> 00:09:39,919 In a dramatic gesture to show his contempt for the medical authorities, 105 00:09:40,720 --> 00:09:42,080 he burned their books. 106 00:09:46,049 --> 00:09:50,309 He was forced to leave Baal University and fled to Germany, 107 00:09:50,309 --> 00:09:53,450 where he would carry on practising his medicine and alchemy. 108 00:09:53,450 --> 00:10:04,080 But he'd paved the way for a new era of questioning, 109 00:10:04,580 --> 00:10:08,639 at a time when many alchemists were more interested in making gold. 110 00:10:09,299 --> 00:10:12,139 They would heat metals in scorching furnaces. 111 00:10:12,759 --> 00:10:14,240 They'd boil, they'd distill. 112 00:10:16,220 --> 00:10:21,100 And it was the pursuit of gold that led to the first major breakthrough 113 00:10:21,100 --> 00:10:23,519 in the hunt to discover elements. 114 00:10:25,080 --> 00:10:29,120 For the alchemists, gold was like the Holy Grail. 115 00:10:29,120 --> 00:10:34,320 They believed it possessed spiritual, magical, even medical properties. 116 00:10:35,000 --> 00:10:37,679 It was the stuff of power, the colour of the sun. 117 00:10:38,120 --> 00:10:40,460 It was made into crowns and coins. 118 00:10:41,159 --> 00:10:45,799 It adorned kings, queens, palaces and temples for over thousands of years. 119 00:10:48,419 --> 00:10:54,740 In ancient Egypt, gold was thought to be the skin of the gods. 120 00:10:55,200 --> 00:11:01,779 To the Inca civilisation, gold was the sweat of the sun. 121 00:11:02,259 --> 00:11:09,159 The alchemists didn't yet know what an element was, 122 00:11:09,659 --> 00:11:12,899 but some unwittingly touched on the idea 123 00:11:12,899 --> 00:11:15,639 that they could be hidden within other substances 124 00:11:15,639 --> 00:11:20,700 when they suggested that gold might be concealed within the human body. 125 00:11:25,230 --> 00:11:27,789 The relentless pursuit of this obsession 126 00:11:27,789 --> 00:11:31,309 led one alchemist to become the first person 127 00:11:31,309 --> 00:11:34,549 credited with the discovery of a new element, 128 00:11:35,389 --> 00:11:36,629 Hennig Brandt. 129 00:11:36,629 --> 00:11:43,049 He was searching for a way of extracting gold from the body 130 00:11:43,049 --> 00:11:46,250 when he hit upon what seemed like a smart idea. 131 00:11:47,309 --> 00:11:50,950 A gold-coloured liquid in plentiful supply. 132 00:11:52,250 --> 00:11:52,850 Urine. 133 00:11:55,950 --> 00:12:01,929 It was 1669, and in the dark, smelly basement of his Hamburg house, 134 00:12:02,549 --> 00:12:05,190 Brandt's expensive alchemical experiments 135 00:12:05,190 --> 00:12:09,509 were rapidly eating through the funds of his wealthy wife, Margarita. 136 00:12:10,070 --> 00:12:12,789 But now, with his urine brainwave, 137 00:12:13,230 --> 00:12:17,049 Brandt believed that he was on the threshold of a momentous discovery. 138 00:12:17,549 --> 00:12:20,389 He was about to make his name and restore his family fortune. 139 00:12:20,990 --> 00:12:23,990 All he needed was another 50 buckets of urine. 140 00:12:27,250 --> 00:12:31,509 Chemist Dr Andrea Sella has been studying Brandt's work 141 00:12:31,509 --> 00:12:34,809 and is going to attempt to find the hidden element. 142 00:12:34,809 --> 00:12:36,809 If you pass me the urine... 143 00:12:36,809 --> 00:12:38,809 You're welcome. 144 00:12:38,809 --> 00:12:41,809 ..and this is courtesy of myself. 145 00:12:41,809 --> 00:12:43,809 I'm already holding my breath. 146 00:12:43,809 --> 00:12:47,809 This is... Look, you know, you mustn't overreact. 147 00:12:47,809 --> 00:12:49,809 So what would Brandt have done? 148 00:12:49,809 --> 00:12:51,809 Well, what Brandt was trying to do 149 00:12:51,809 --> 00:12:53,809 was really to get to the heart of the matter, 150 00:12:53,809 --> 00:12:55,809 to start boiling it down, 151 00:12:55,809 --> 00:12:57,809 to get rid of the sort of unimportant parts, 152 00:12:57,809 --> 00:13:00,809 and that, of course, was principally the water. 153 00:13:00,809 --> 00:13:03,809 There is an additional feature, and it's not really surprising, 154 00:13:03,809 --> 00:13:11,990 really surprising, but you know, have a quick waft of that, and yeah, it's pretty bad. 155 00:13:11,990 --> 00:13:16,169 I mean, Brandt must have had some very, very patient neighbors, and I really don't know 156 00:13:16,169 --> 00:13:22,690 what his romantic life must have been like, but I can't imagine he was all that popular. 157 00:13:22,690 --> 00:13:28,570 You see, I can understand Jürgen being gold-colored, but Brandt was looking to make gold. 158 00:13:28,570 --> 00:13:29,570 What is the connection? 159 00:13:29,570 --> 00:13:32,830 First of all, it seems tremendously laughable to us 160 00:13:32,830 --> 00:13:36,210 to use something as disgusting a waste product as urine. 161 00:13:36,450 --> 00:13:40,970 One of the alchemical views was that man was really a microcosm of the universe 162 00:13:40,970 --> 00:13:47,009 and therefore urine actually carried within it some of that vital force, the life force. 163 00:13:47,149 --> 00:13:50,370 So sort of a metaphysical symbol of life. 164 00:13:50,529 --> 00:13:54,429 Absolutely. And so really this was a substance of power. 165 00:13:55,490 --> 00:13:59,149 Brandt was determined to persevere with his quest for gold. 166 00:13:59,570 --> 00:14:02,169 He distilled the urine down to a paste, 167 00:14:02,669 --> 00:14:06,490 then heated it at a phenomenal temperature for several days. 168 00:14:07,549 --> 00:14:12,509 Eventually, wisps of smoke revealed tiny fragments that combusted in air. 169 00:14:13,649 --> 00:14:15,769 But what was this fiery substance? 170 00:14:16,450 --> 00:14:21,529 It wasn't golden like the sun, but it burned brighter than any medieval candle. 171 00:14:21,889 --> 00:14:39,019 So this is what Brandt isolated from urine. 172 00:14:40,019 --> 00:14:41,000 It's not gold. 173 00:14:41,000 --> 00:14:42,940 This is phosphorus. 174 00:14:44,860 --> 00:14:48,539 Brandt had discovered, completely by accident, 175 00:14:49,120 --> 00:14:52,200 a new element, never seen by man, 176 00:14:52,799 --> 00:14:54,220 fiery phosphorus. 177 00:14:55,960 --> 00:14:58,019 He was looking for riches, 178 00:14:58,600 --> 00:15:02,139 but didn't realise that he'd unearthed a fundamental notion, 179 00:15:02,720 --> 00:15:06,299 that elements could be concealed within a hidden world. 180 00:15:08,120 --> 00:15:10,559 Phosphorus is biologically very, very important. 181 00:15:10,559 --> 00:15:14,980 If you think of our bones, they're composed predominantly of calcium hydroxyphosphate. 182 00:15:15,080 --> 00:15:16,679 So there's lots of phosphate there. 183 00:15:17,039 --> 00:15:17,960 It's in our DNA. 184 00:15:18,500 --> 00:15:20,220 It's in all sorts of our tissues. 185 00:15:20,679 --> 00:15:26,000 And as a result, there's always phosphate in the blood, and some of it, excess, is transferred into the urine. 186 00:15:26,240 --> 00:15:28,580 A little bit less than about a gram per liter. 187 00:15:29,360 --> 00:15:31,059 This stuff is a complete tiger. 188 00:15:31,500 --> 00:15:36,200 You can immediately see that it starts to smoke very gently in air. 189 00:15:36,200 --> 00:15:39,779 And this is really a warning to us that things are going to happen 190 00:15:39,779 --> 00:15:42,120 if we don't sort of deal with it quickly. 191 00:15:42,279 --> 00:15:45,179 So we're going to drop it into this flask. 192 00:15:45,399 --> 00:15:47,559 The flask is actually filled with oxygen, 193 00:15:47,899 --> 00:15:53,980 and so it's sitting in sand just to keep the heat from attacking the glass. 194 00:15:54,120 --> 00:15:57,240 Now, I'm going to touch it with a hot glass rod. 195 00:16:05,220 --> 00:16:08,370 And so there it is. 196 00:16:09,230 --> 00:16:10,149 That's fantastic. 197 00:16:11,009 --> 00:16:13,049 And it sort of feels cold. 198 00:16:13,049 --> 00:16:19,929 it's not it's not hot that's quite beautiful because it shone so vividly it was cold enough 199 00:16:19,929 --> 00:16:33,690 to hold brant called his discovery icy noctiluca cold night light phosphorus it's in every cell 200 00:16:33,690 --> 00:16:40,889 in the human body it's used in drugs to promote bone growth treating diseases like osteoporosis 201 00:16:40,889 --> 00:16:47,710 153 million tonnes of phosphorus are produced every year. 202 00:16:47,710 --> 00:16:51,710 Its phosphate is consumed as a food supplement 203 00:16:51,710 --> 00:16:54,710 and as an ingredient of toothpaste. 204 00:16:54,710 --> 00:16:58,710 But eating just 100 milligrams of pure phosphorus, 205 00:16:58,710 --> 00:17:01,710 enough to coat a fingertip, could be fatal. 206 00:17:04,710 --> 00:17:07,710 And it has an even darker side. 207 00:17:07,710 --> 00:17:09,710 In the Second World War, 208 00:17:09,710 --> 00:17:14,710 Phosphorus was used in the thousands of bombs dropped on Hamburg, 209 00:17:14,710 --> 00:17:17,710 the city where Brandt discovered it. 210 00:17:17,710 --> 00:17:30,829 Brandt hoped that Phosphorus would make him a fortune, 211 00:17:30,829 --> 00:17:32,829 but his cash ran out 212 00:17:32,829 --> 00:17:36,829 and he sold the secret of his discovery for a paltry sum. 213 00:17:37,829 --> 00:17:42,829 Before long, Phosphorus was being touted round the royal courts of Europe. 214 00:17:42,829 --> 00:17:48,529 And in 1677, it arrived at the court of King Charles II. 215 00:17:49,390 --> 00:17:54,410 Soon after, wealthy alchemist Robert Boyle witnessed its luminous magic 216 00:17:54,410 --> 00:17:57,250 and determined to investigate its properties. 217 00:17:58,890 --> 00:18:03,789 Dr Andrea Sella and I are going to follow Boyle's own instructions 218 00:18:03,789 --> 00:18:07,950 to attempt one of his most significant experiments on phosphorus. 219 00:18:08,470 --> 00:18:12,089 So I have here extracts from Robert Boyle's book, 220 00:18:12,089 --> 00:18:16,650 New experiments and observations made upon the icy Noctiluca. 221 00:18:16,970 --> 00:18:21,250 Having put together about half a grain of our dry Noctiluca matter, 222 00:18:21,750 --> 00:18:22,869 how much is half a grain? 223 00:18:22,890 --> 00:18:24,730 Well, half a grain really isn't very much. 224 00:18:26,029 --> 00:18:30,630 There's 7,000 grains to the pound, so you can work it out. 225 00:18:30,730 --> 00:18:31,490 You're the physicist. 226 00:18:32,450 --> 00:18:36,750 Okay, and six times its weight of common flowers of sulphur. 227 00:18:37,309 --> 00:18:39,730 Okay, so we'll put a little piece... 228 00:18:39,730 --> 00:18:41,089 So that's just sulphur powder, is it? 229 00:18:41,089 --> 00:18:44,490 It's just, yeah, it's essentially sulfur, finely powdered sulfur. 230 00:18:44,730 --> 00:18:48,369 Right, and it says they were lodged in the fold of a piece of white paper. 231 00:18:48,750 --> 00:18:51,049 He said he rubbed it with the haft of a knife. 232 00:18:51,390 --> 00:18:55,829 Well, I haven't got a knife, but I do have a spatula, so I'll use that. 233 00:18:56,130 --> 00:18:59,190 Okay, it's beginning to smoke. There it is. It's beginning to kindle. 234 00:18:59,390 --> 00:19:01,450 We've got a little bit of fire there already. 235 00:19:01,569 --> 00:19:03,269 The main lump of phosphorus hasn't gone. 236 00:19:03,269 --> 00:19:03,750 Oh, there it goes. 237 00:19:03,750 --> 00:19:05,009 There it goes, there it goes. Whoa! 238 00:19:07,250 --> 00:19:08,630 Didn't have time to bruise it. 239 00:19:08,849 --> 00:19:10,369 Didn't have time, you didn't need bruising. 240 00:19:10,369 --> 00:19:16,289 so you've basically recreated what is the precursor to the match yes and i also got 241 00:19:16,289 --> 00:19:23,009 some splendid smoke rings here i mean this would really sort of radically transform things because 242 00:19:23,009 --> 00:19:33,190 what you had was fire on demand boyle had stumbled upon the essential ingredient of a match a huge 243 00:19:33,190 --> 00:19:38,630 industry was spawned from this single experiment but boyle wasn't really interested in the money 244 00:19:38,630 --> 00:19:44,950 making potential of phosphorus just understanding the properties of this element was reward enough 245 00:19:44,950 --> 00:20:04,920 for him so phosphorus did have transformational powers after all it may not have changed lead 246 00:20:04,920 --> 00:20:13,480 into gold but it turned an alchemist into the first modern chemist boyle had set the stage 247 00:20:13,480 --> 00:20:20,920 for future element hunters unlike most alchemists he shared his methods and was able to pass on the 248 00:20:20,920 --> 00:20:29,849 tools they needed to help unlock the mysteries of matter. I've come to search the vaults 249 00:20:29,849 --> 00:20:38,190 of the Royal Society in London. What I'm looking for was deposited here in 1661, just one year 250 00:20:38,190 --> 00:20:49,569 after the Society was formed. Here it is. The Skeptical Chemist. It was written by Robert 251 00:20:49,569 --> 00:20:52,529 Boyle, who was one of the founders of the Royal Society. 252 00:20:54,529 --> 00:21:00,650 Dr Anna-Marie Roos, a specialist in the history of chemistry, has studied Boyle's writings. 253 00:21:01,190 --> 00:21:05,910 I've got a copy of Boyle's Skeptical Chemist. Why was this book so important? 254 00:21:06,269 --> 00:21:13,109 This is really considered to be one of the books that signifies a transition from alchemy to 255 00:21:13,109 --> 00:21:18,029 chemistry. And some scholars have thought it's the first book of chemistry. The fact that that 256 00:21:18,029 --> 00:21:24,369 book was written in plain English was also quite a new thing. You only have to compare Boyle's book 257 00:21:24,369 --> 00:21:31,009 to the cryptic writings of another alchemist, that great man of science Isaac Newton, to appreciate 258 00:21:31,009 --> 00:21:37,849 its innovation. And we can see here that it is in Latin and we also can see that there are several 259 00:21:37,849 --> 00:21:44,410 alchemical symbols being used for the chemical elements. It really does remind me of astrology 260 00:21:44,410 --> 00:21:46,849 and even Egyptian hieroglyphics. 261 00:21:46,890 --> 00:21:47,329 Absolutely. 262 00:21:47,609 --> 00:21:51,930 And I compare that with Boyle, where he says things like, 263 00:21:52,130 --> 00:21:54,630 he took 200 pounds of earth, dried it in an oven, 264 00:21:54,809 --> 00:21:57,490 having put it in an earthen vessel and melted it. 265 00:21:57,829 --> 00:22:00,049 He's describing a chemical process. 266 00:22:00,170 --> 00:22:00,609 Absolutely. 267 00:22:00,869 --> 00:22:05,410 What made Boyle a bit different is that he was willing to divulge 268 00:22:06,230 --> 00:22:10,549 some of his chemical secrets for the good of the scientific community. 269 00:22:13,859 --> 00:22:16,859 Boyle was bringing alchemy out of the shadows. 270 00:22:17,000 --> 00:22:20,599 and into an enlightened, rational age. 271 00:22:20,940 --> 00:22:24,220 He was opening up the scientific method for everyone to see. 272 00:22:25,099 --> 00:22:28,119 The alchemist must have feared he was giving away their secrets, 273 00:22:28,680 --> 00:22:31,720 but he wasn't so much interested in debunking alchemy 274 00:22:31,720 --> 00:22:34,559 as getting rid of its metaphysical baggage 275 00:22:34,559 --> 00:22:38,640 and replacing it with a more rigorous scientific approach. 276 00:22:38,640 --> 00:22:48,049 A new age of scientific experimentation had begun. 277 00:22:52,569 --> 00:22:59,349 And with a more open exchange of ideas came a rejection of tradition. 278 00:23:00,130 --> 00:23:04,930 It heralded an era in which the ancient Greek doctrines were re-evaluated 279 00:23:04,930 --> 00:23:07,609 and new concepts introduced. 280 00:23:10,349 --> 00:23:13,109 Copernicus challenged the ancient idea 281 00:23:13,109 --> 00:23:15,869 that the Earth was at the centre of the universe, 282 00:23:16,450 --> 00:23:19,710 proposing instead that it was just one of a number of planets 283 00:23:19,710 --> 00:23:21,430 orbiting around the sun. 284 00:23:22,289 --> 00:23:24,369 Vesalius mapped the human body. 285 00:23:24,369 --> 00:23:30,910 It was an exciting and liberating time in which Europe was being dragged out of its dark ages 286 00:23:30,910 --> 00:23:42,660 and into an age of reason. But just because people were thinking differently didn't necessarily mean 287 00:23:42,660 --> 00:23:47,940 that they were getting it right. And while a new generation of scientists were keen to come up with 288 00:23:47,940 --> 00:23:54,920 modern elements to replace the four ancient ones, their enthusiasm didn't stop them from buying into 289 00:23:54,920 --> 00:23:57,480 to completely false theories. 290 00:23:57,480 --> 00:23:59,700 And so it was that science went up 291 00:23:59,700 --> 00:24:01,900 one of the greatest blind alleys 292 00:24:01,900 --> 00:24:03,420 in the history of chemistry. 293 00:24:06,259 --> 00:24:10,759 It was 1667, a year after the Great Fire of London 294 00:24:10,759 --> 00:24:16,319 had razed one of Europe's greatest cities to the ground. 295 00:24:16,319 --> 00:24:19,180 The mysteries of fire were at the forefront 296 00:24:19,180 --> 00:24:22,420 of everyone's minds, but no one really understood 297 00:24:22,420 --> 00:24:25,380 what fire was or how it was created. 298 00:24:26,420 --> 00:24:31,420 German chemist Johann Becher proposed that the destructive power of fire 299 00:24:31,420 --> 00:24:36,420 was caused by an ethereal entity named phlogiston. 300 00:24:36,420 --> 00:24:40,420 It was thought to be an odourless, colourless, tasteless 301 00:24:40,420 --> 00:24:44,420 and weightless substance that causes things to burn, 302 00:24:44,420 --> 00:24:47,420 reducing them to their true form. 303 00:24:47,420 --> 00:24:51,420 This burning wood produces ash, 304 00:24:51,420 --> 00:25:00,140 ash. So wood must be made up of ash, pure wood, plus phlogiston. 305 00:25:00,140 --> 00:25:06,559 The notion of phlogiston seemed so credible in the 17th century that it consumed the scientific 306 00:25:06,559 --> 00:25:14,119 community. It was accepted as a truth, virtually paralysing our ability to discover more elements 307 00:25:14,119 --> 00:25:20,720 and map the contours of the natural world. One great chemist who experimented with gases 308 00:25:20,720 --> 00:25:23,039 even claimed to have isolated it. 309 00:25:24,579 --> 00:25:28,779 On the same day, every week, for 50 years, 310 00:25:29,259 --> 00:25:34,279 a rather peculiar scientist came to the Royal Society dinner club 311 00:25:34,279 --> 00:25:37,059 to discuss the latest scientific ideas. 312 00:25:42,500 --> 00:25:46,960 Henry Cavendish has been described as the richest of the learned 313 00:25:46,960 --> 00:25:49,400 and the most learned of the rich. 314 00:25:49,799 --> 00:25:52,140 He was a major shareholder in the Bank of England 315 00:25:52,140 --> 00:26:00,960 and had royal connections but it's remarkable he came to a social gathering at all Cavendish 316 00:26:00,960 --> 00:26:08,579 was painfully shy and lived in virtual isolation at home he insisted that his servants only 317 00:26:08,579 --> 00:26:14,099 communicate with him in writing colleagues at the dinner club said that he'd often be found outside 318 00:26:14,099 --> 00:26:20,759 trying to pluck up the courage to go in and when speaking to him it was best to look into the air 319 00:26:20,759 --> 00:26:26,519 with vacancy rather than directly at him despite signs of what we might recognize 320 00:26:26,519 --> 00:26:32,039 today as autism Cavendish made a vital contribution to the discovery of the 321 00:26:32,039 --> 00:26:41,140 elements I'm going to investigate how Cavendish's experiments with heirs led 322 00:26:41,140 --> 00:26:53,029 him to find the first element that's a gas Cavendish added a metal zinc to an 323 00:26:53,029 --> 00:27:01,490 acid it was deceptively simple and pretty soon bubbles began to appear on 324 00:27:01,490 --> 00:27:08,089 the surface of the zinc Cavendish started to collect this gas which I'm 325 00:27:08,089 --> 00:27:13,789 going to do in this test tube it didn't smell of anything it didn't taste of 326 00:27:13,789 --> 00:27:18,470 anything in fact it was completely invisible Cavendish soon realized this 327 00:27:18,470 --> 00:27:32,069 was no ordinary gas and then he set light to it Cavendish had no idea he'd discovered a new 328 00:27:32,069 --> 00:27:38,150 element in fact he thought he'd found a new kind of air different to the air we breathe he called 329 00:27:38,150 --> 00:27:45,710 it not surprisingly inflammable air and he believed his inflammable air had to be the 330 00:27:45,710 --> 00:27:55,630 mysterious phlogiston it was odorless tasteless colorless and most importantly it caught fire 331 00:27:56,190 --> 00:28:04,349 it had to be phlogiston but he was wrong cavendish didn't realize it but he had isolated a new 332 00:28:04,349 --> 00:28:14,829 element hydrogen he investigated the characteristics of his new air and calculated that it was 11 times 333 00:28:14,829 --> 00:28:22,029 lighter than the air we breathe now i've got asthma here to help me she's pumping 334 00:28:22,029 --> 00:28:27,309 hydrogen through into this washing up liquid and creating bubbles of hydrogen coming up 335 00:28:27,309 --> 00:28:31,789 through this funnel because hydrogen is so much lighter than air at some point these 336 00:28:31,789 --> 00:28:39,869 bubbles will separate and start to float up brilliant that was really beautiful 337 00:28:39,869 --> 00:28:47,910 it was lighter than air and burst into flames you can see why Cavendish thought 338 00:28:47,910 --> 00:28:55,470 it was phlogiston oh they're getting better but this belief meant Cavendish 339 00:28:55,470 --> 00:29:03,190 wasn't credited with the discovery of hydrogen during his lifetime nor would 340 00:29:03,190 --> 00:29:15,569 he witness its full force? Hydrogen, produced just after the Big Bang alongside helium and 341 00:29:15,569 --> 00:29:24,309 lithium, it's the most abundant and lightest element in the universe. The sun's energy 342 00:29:24,309 --> 00:29:32,269 comes from the nuclear fusion of hydrogen, the same principle harnessed in the hydrogen 343 00:29:32,269 --> 00:29:43,269 bomb. Hydrogen's highly flammable nature was witnessed when it ignited the Hindenburg Zeppelin 344 00:29:43,269 --> 00:30:04,970 airship in 1937, killing 36 people. Like so many other element hunters, Cavendish didn't 345 00:30:04,970 --> 00:30:10,130 realise the significance of his discovery, but he did observe something that will play 346 00:30:10,130 --> 00:30:17,019 a crucial role in our understanding of the natural world. 347 00:30:17,019 --> 00:30:25,700 Each time he set light to the gas a dewy liquid began to appear on the surface of the glass. 348 00:30:25,700 --> 00:30:32,440 It was water. Now this had incredible implications back in the 1700s because back then they believed 349 00:30:32,440 --> 00:30:38,819 in the ancient Greek idea that water was an element. But if you can make water out of 350 00:30:38,819 --> 00:30:46,339 two other constituents then it couldn't be an element in fact water is a compound 351 00:30:54,359 --> 00:30:59,079 this struck right to the heart of the ancient concept of four elements 352 00:31:01,160 --> 00:31:05,880 cavendish's observations could have shaken the foundations of accepted belief 353 00:31:06,440 --> 00:31:13,799 but they didn't because he was thrown off course by flogiston he reckoned that the heirs 354 00:31:13,799 --> 00:31:22,200 must contain a form of water modified by the presence of phlogiston it simply didn't occur 355 00:31:22,200 --> 00:31:30,039 to him that water was a compound so while he was very close to destroying the temple of the ancient 356 00:31:30,039 --> 00:31:37,319 four elements he couldn't quite yet disprove them the pillars of that temple were now standing on 357 00:31:37,319 --> 00:31:43,559 very shaky ground and it wouldn't be too long before they'd come crashing down but it wasn't 358 00:31:43,559 --> 00:31:48,519 cavendish's water that would finally disprove the ancient theory it was air 359 00:31:55,849 --> 00:32:03,130 19 of what we now call elements had been found so far but 18th century scientists 360 00:32:03,130 --> 00:32:06,890 were still grappling to work out what the world was made of 361 00:32:09,450 --> 00:32:14,650 the royal society had commissioned its members to investigate the invisible heirs 362 00:32:18,490 --> 00:32:25,269 By the mid-1700s, there were three known types of air, or gases. 363 00:32:26,009 --> 00:32:28,130 There was the common air that we breathe, 364 00:32:28,690 --> 00:32:30,789 inflammable air, now known as hydrogen, 365 00:32:31,250 --> 00:32:33,970 and fixed air, or carbon dioxide. 366 00:32:34,950 --> 00:32:39,150 And experimenting with these airs was a favourite pastime 367 00:32:39,150 --> 00:32:43,190 of clergyman and amateur chemist Joseph Priestley. 368 00:32:44,910 --> 00:32:47,509 Priestley lived next to a brewery 369 00:32:47,509 --> 00:32:49,849 and spent rather a lot of time there, 370 00:32:50,470 --> 00:32:52,990 especially considering he was a Unitarian minister 371 00:32:52,990 --> 00:32:55,650 known for his extreme sermons. 372 00:32:56,750 --> 00:33:00,789 But he wasn't here for the beer. 373 00:33:01,650 --> 00:33:03,549 Priestley was interested in the gas 374 00:33:03,549 --> 00:33:06,289 that's produced in the fermentation process. 375 00:33:07,349 --> 00:33:09,230 He called it brewery gas. 376 00:33:09,710 --> 00:33:11,549 But, of course, it was well known by that time. 377 00:33:11,630 --> 00:33:12,970 It was known as fixed air. 378 00:33:13,490 --> 00:33:16,130 We know it today as carbon dioxide. 379 00:33:16,130 --> 00:33:22,690 Carbon dioxide is being produced inside this vat and is, because it's heavier than air, 380 00:33:22,690 --> 00:33:25,450 pouring out and cascading down. 381 00:33:25,450 --> 00:33:31,450 Now we can't see it, but an experiment that Priestley himself carried out involved seeing 382 00:33:31,450 --> 00:33:37,000 what carbon dioxide does to a lit flame. 383 00:33:37,000 --> 00:33:42,640 So if I hold this flame here, it's not in the path of the gas at the moment, but if 384 00:33:42,640 --> 00:33:47,819 I bring it down, you can see it immediately extinguishes. 385 00:33:47,819 --> 00:33:54,839 You can even see the trail of smoke following the path of the gas. 386 00:33:54,839 --> 00:33:58,059 Priestley was fascinated by fixed air. 387 00:33:58,059 --> 00:34:03,660 He mixed it with water and so invented the first fizzy drink. 388 00:34:03,660 --> 00:34:09,219 In time, it would spawn an industry worth millions, but he earned almost nothing from 389 00:34:09,219 --> 00:34:10,219 it. 390 00:34:10,219 --> 00:34:17,239 Instead, Priestley's passion for science led to an invitation to Bowood House in Wiltshire 391 00:34:17,239 --> 00:34:23,590 to tutor the children of the future Prime Minister, Lord Shelburne. 392 00:34:23,590 --> 00:34:28,989 Priestley lacked the wealth of earlier chemists like Boyle and Cavendish, 393 00:34:28,989 --> 00:34:33,909 and he made little money from his inventions and his radical writings. 394 00:34:33,909 --> 00:34:37,190 Lord Shelburne was offering him financial stability 395 00:34:37,190 --> 00:34:40,389 and the chance to continue with his scientific experiments 396 00:34:40,389 --> 00:34:42,110 in return for teaching. 397 00:34:42,110 --> 00:34:46,949 So he became the first professional salaried chemist. 398 00:34:46,949 --> 00:34:50,769 And it was here that he continued his experiments with airs. 399 00:34:55,619 --> 00:34:58,719 On 1st August 1774, 400 00:34:58,719 --> 00:35:03,500 he performed one of the most important experiments in chemical history. 401 00:35:05,139 --> 00:35:10,099 Priestley was gripped by unlocking the elemental secrets of the airs. 402 00:35:10,539 --> 00:35:15,579 On this occasion, he started with a powder he knew as mercuric calx, 403 00:35:16,159 --> 00:35:17,199 mercuric oxide. 404 00:35:18,199 --> 00:35:23,519 He put it in a test tube to collect any gas it might give off when he heated it. 405 00:35:25,039 --> 00:35:29,800 Then he filled the test tube with mercury, which would trap the gas. 406 00:35:31,059 --> 00:35:33,940 OK, so I now place my finger over the top of the tube, 407 00:35:34,539 --> 00:35:38,260 invert it so that it's submerged into the mercury bath. 408 00:35:38,739 --> 00:35:44,039 I now have the mercuric oxide powder at the very top of the tube. 409 00:35:44,039 --> 00:35:48,159 What Priestley did next was heat up this powder 410 00:35:48,159 --> 00:35:54,050 The level of the mercury in the tube is dropping 411 00:35:54,050 --> 00:36:00,130 What's going on is that a gas is being produced that's pushing the mercury down 412 00:36:00,130 --> 00:36:04,469 What in fact is happening is that this mercuric oxide powder 413 00:36:04,469 --> 00:36:07,610 is being broken up into its two components 414 00:36:07,610 --> 00:36:12,809 I'm now going to see what gas Priestley had made 415 00:36:12,809 --> 00:36:18,789 If I take this splint and blow it out so I just have a glowing ember, 416 00:36:19,489 --> 00:36:22,449 it bursts back into flame again. 417 00:36:23,190 --> 00:36:26,989 We now know that Joseph Priestley had found oxygen. 418 00:36:27,690 --> 00:36:30,429 But because he believed in the idea of phlogiston, 419 00:36:30,969 --> 00:36:36,650 he thought the splint was introducing phlogiston to the new air and catching fire. 420 00:36:37,269 --> 00:36:41,309 He concluded that his air must be without phlogiston. 421 00:36:42,110 --> 00:36:45,730 So he called it dephlogisticated air. 422 00:36:47,130 --> 00:36:50,670 Priestley's experiments with his new air didn't stop there. 423 00:36:51,130 --> 00:36:52,510 In fact, they got stranger. 424 00:36:53,289 --> 00:36:57,769 He placed a mouse inside a sealed container filled with the new air, 425 00:36:58,369 --> 00:37:00,510 expecting it to live for just 15 minutes. 426 00:37:01,190 --> 00:37:04,829 Instead, he found it alive and well after half an hour. 427 00:37:05,489 --> 00:37:08,969 He then tried breathing it himself and noted, 428 00:37:08,969 --> 00:37:15,010 I fancy my breast felt particularly light and easy after some time. 429 00:37:15,530 --> 00:37:18,829 Who can tell but that in time this pure air 430 00:37:18,829 --> 00:37:22,309 may become a fashionable article of luxury. 431 00:37:23,230 --> 00:37:27,570 Hitherto just two mice and I have had the privilege of breathing it. 432 00:37:29,230 --> 00:37:31,010 Little did Priestley know, 433 00:37:31,429 --> 00:37:34,389 but everyone had had the privilege of breathing it. 434 00:37:34,389 --> 00:37:42,630 Oxygen is the third most abundant element in the universe 435 00:37:42,630 --> 00:37:46,070 and makes up over half the weight of a human body. 436 00:37:47,130 --> 00:37:53,869 At minus 183 degrees Celsius, it condenses to a pale blue liquid. 437 00:37:55,349 --> 00:38:00,650 Steel smelting uses more than half the world's commercially produced oxygen. 438 00:38:01,530 --> 00:38:03,409 It's also used in rocket fuel. 439 00:38:05,960 --> 00:38:12,559 Around 21% of air is oxygen, a few percent less and we couldn't breathe, 440 00:38:12,559 --> 00:38:18,599 a few percent more and any organic matter ignited would burn out of control. 441 00:38:25,659 --> 00:38:32,519 Although Priestley knew he'd found something special, he didn't realise he'd isolated an element. 442 00:38:32,519 --> 00:38:38,440 He was still hampered by his belief in Flodgestan, 443 00:38:38,920 --> 00:38:42,139 but his path was about to cross with a visionary 444 00:38:42,139 --> 00:38:45,880 who was also thinking about gases and airs. 445 00:38:50,860 --> 00:38:57,840 In October 1774, Priestley accompanied his benefactor, Lord Shelburne, 446 00:38:58,019 --> 00:39:00,019 on a grand tour of Europe. 447 00:39:05,019 --> 00:39:09,179 They headed to Paris, where they were invited to dine 448 00:39:09,179 --> 00:39:11,980 with some of the country's most pre-eminent scientists. 449 00:39:12,539 --> 00:39:16,280 It must have been quite an occasion for a down-to-earth Yorkshireman like Priestley. 450 00:39:17,219 --> 00:39:21,940 One of the guests there was the stellar French scientist Antoine Lavoisier. 451 00:39:22,599 --> 00:39:27,179 By the age of 28, he'd already been elected to the French Academy of Sciences. 452 00:39:28,619 --> 00:39:29,679 This guy was incredible. 453 00:39:29,860 --> 00:39:33,340 He'd published everything from the mineralogy of the Pyrenees 454 00:39:33,340 --> 00:39:37,760 through to locating the best sites for abattoirs in Paris. 455 00:39:44,940 --> 00:39:50,139 Lavoisier was not only a member of a newly emerging scientific elite, 456 00:39:50,139 --> 00:39:55,000 but a tax collector and an extremely wealthy member of the bourgeoisie. 457 00:39:55,639 --> 00:40:00,219 And he was determined to crack open the mysteries of the natural world. 458 00:40:02,119 --> 00:40:05,039 When Lavoisier and Priestley met over dinner, 459 00:40:05,360 --> 00:40:12,159 they talked chemistry and conversations soon turned to Priestley's exciting new discovery of 460 00:40:12,159 --> 00:40:20,559 deflogisticated air. Lavoisier intrigued pressed him for details and Priestley clearly found him 461 00:40:20,559 --> 00:40:31,500 a very attentive listener because he told him all about his experiment. Lavoisier and Priestley were 462 00:40:31,500 --> 00:40:32,940 were like chalk and cheese. 463 00:40:34,320 --> 00:40:37,900 Lavoisier had the best-equipped laboratory in Europe 464 00:40:37,900 --> 00:40:42,340 with more than 10,000 pieces of precision technology. 465 00:40:44,199 --> 00:40:46,460 Priestley worked in a makeshift lab 466 00:40:46,460 --> 00:40:48,940 with equipment he'd just cobbled together. 467 00:40:50,539 --> 00:40:53,460 Lavoisier weighed, measured, reweighed 468 00:40:54,019 --> 00:40:58,179 and calculated precisely before and after every reaction. 469 00:40:58,179 --> 00:41:07,460 and he applied this approach to investigate the great mystery of phlogiston lavoisier's breakthrough 470 00:41:07,460 --> 00:41:13,780 came when he turned his fanatical attention to detail to the weight of substances before 471 00:41:13,780 --> 00:41:24,630 and after they were heated he first weighed a metal very precisely in this case tin and if i 472 00:41:24,630 --> 00:41:31,199 I check the reading, it's 150.07 grams. 473 00:41:31,460 --> 00:41:33,780 Heating tin and then reweighing it 474 00:41:33,780 --> 00:41:37,760 revealed a nagging problem with the theory of phlogiston. 475 00:41:37,760 --> 00:41:40,780 If phlogiston is given off when a substance is heated, 476 00:41:40,780 --> 00:41:42,519 it should weigh less. 477 00:41:43,599 --> 00:41:47,000 But here the reading is 153.6 grams. 478 00:41:47,000 --> 00:41:51,139 That's nearly four grams more than before it was heated. 479 00:41:51,139 --> 00:41:54,559 Here's where Lavoisier had his flash of inspiration. 480 00:41:54,559 --> 00:41:57,260 Maybe phlogiston isn't given off when a substance is heated. 481 00:41:57,659 --> 00:42:00,880 Instead, maybe it absorbs some kind of air. 482 00:42:01,380 --> 00:42:03,340 That would explain this increase. 483 00:42:03,880 --> 00:42:07,900 But if that was true, what was it that was being added? 484 00:42:13,219 --> 00:42:15,800 Fresh from his conversation with Priestley, 485 00:42:16,420 --> 00:42:21,519 Lavoisier decided to repeat Priestley's experiment, only in reverse. 486 00:42:21,519 --> 00:42:33,519 he heated some mercury inside a sealed container until it turned into mercuric oxide which is the 487 00:42:33,519 --> 00:42:39,619 same substance that priestly had used in his experiment he measured the amount of air that 488 00:42:39,619 --> 00:42:46,260 was absorbed by the mercury when it was heated he then heated the mercuric oxide and observed that 489 00:42:46,260 --> 00:42:51,880 the amount of air released was exactly the same as the amount of air that had been absorbed by 490 00:42:51,880 --> 00:42:58,440 the mercury when it was heated. So in a flash of inspiration he realised that something in the air 491 00:42:58,440 --> 00:43:04,719 had been taken in by the mercury to make the mercuric oxide and that same gas had then been 492 00:43:04,719 --> 00:43:12,559 released. He had the courage to conclude that this gas had nothing to do with phlogiston. In fact it 493 00:43:12,559 --> 00:43:19,519 was a brand new element. Lavoisier called it oxygen. So thanks to Priestley's experiment 494 00:43:19,519 --> 00:43:23,519 Lavoisier had exposed the truth of the red herring 495 00:43:23,519 --> 00:43:26,519 that had hampered chemistry for a century. 496 00:43:26,519 --> 00:43:31,519 Finally, Lavoisier had shown that phlogiston simply didn't exist. 497 00:43:35,519 --> 00:43:39,519 Lavoisier had freed chemistry from the shackles of phlogiston, 498 00:43:39,519 --> 00:43:42,519 the remnant of the medieval world view, 499 00:43:42,519 --> 00:43:45,519 and he'd pioneered a scientific method 500 00:43:45,519 --> 00:43:49,760 and so could make rapid progress in mapping the elements. 501 00:43:49,760 --> 00:43:51,659 But to Priestley's anger, 502 00:43:51,659 --> 00:43:55,320 Lavoisier claimed he had discovered oxygen 503 00:43:55,320 --> 00:43:58,159 because he recognized it as a new element. 504 00:43:59,139 --> 00:44:02,079 Trying to resolve who should get the glory 505 00:44:02,079 --> 00:44:04,860 proved to be a messy business. 506 00:44:04,860 --> 00:44:07,599 An embittered war of words and reputations 507 00:44:07,599 --> 00:44:10,179 broke out between England and France. 508 00:44:10,179 --> 00:44:12,719 Priestley was enraged that Lavoisier 509 00:44:12,719 --> 00:44:15,039 had tried to steal his thunder, 510 00:44:15,039 --> 00:44:19,000 And he had a point, because Lavoisier's experiments on oxygen 511 00:44:19,000 --> 00:44:22,980 weren't completed until after he'd met Priestley. 512 00:44:24,500 --> 00:44:27,380 Lavoisier may not have discovered oxygen, 513 00:44:27,860 --> 00:44:30,300 but he had recognised its significance. 514 00:44:31,119 --> 00:44:33,699 And it is Lavoisier, not Priestley, 515 00:44:34,019 --> 00:44:36,380 who's known as the father of chemistry. 516 00:44:37,460 --> 00:44:42,500 The discovery of oxygen had finally crushed any vestiges 517 00:44:42,500 --> 00:44:45,500 of the Greek concept of the four elements. 518 00:44:46,940 --> 00:44:49,619 Water was made of hydrogen and oxygen. 519 00:44:50,440 --> 00:44:53,900 Earth and air were a whole hodgepodge of different elements. 520 00:44:54,639 --> 00:44:57,699 And fire, well, that wasn't an element at all. 521 00:45:04,840 --> 00:45:07,579 Chemistry was being honed into the modern era. 522 00:45:07,579 --> 00:45:10,739 It was an age when chemists were splitting matter, 523 00:45:11,159 --> 00:45:12,420 making great discoveries, 524 00:45:12,880 --> 00:45:15,659 just trying to understand what our world was made of. 525 00:45:15,659 --> 00:45:21,440 But there still didn't seem to be any order, any logic to their findings, 526 00:45:21,940 --> 00:45:25,260 just random elements dotted around the chemical landscape. 527 00:45:30,510 --> 00:45:35,730 Lavoisier was the first scientist to define what an element was, 528 00:45:36,070 --> 00:45:41,010 a substance that could not be decomposed by existing chemical means. 529 00:45:41,869 --> 00:45:43,610 This is the manuscript. 530 00:45:43,610 --> 00:45:49,070 And he set about drawing up a definitive list of all the elements. 531 00:45:49,469 --> 00:45:53,070 Now 33 replace the ancient form. 532 00:45:57,739 --> 00:46:02,500 So this is it. This is Lavoisier's original list of elements. 533 00:46:03,599 --> 00:46:09,139 It's in French and it's in his handwriting, but I can still sort of pick out what it says. 534 00:46:09,559 --> 00:46:13,300 He's divided them up into four groups, four categories of elements. 535 00:46:13,300 --> 00:46:22,199 there's the gases the non-metals metals and earths you can see among the gases he's got 536 00:46:22,199 --> 00:46:30,780 oxygen and hydrogen he didn't get it all right i see he's he lists here arsenic and antimony 537 00:46:30,780 --> 00:46:37,239 among his metals today they're not considered to be metals but even more fascinating he has 538 00:46:37,239 --> 00:46:45,519 lumière, or light, and calorique, heat, listed among his elements in the gases. Of course, 539 00:46:45,519 --> 00:46:52,139 light and heat we know now to be just pure energy. But these mistakes apart, this was 540 00:46:52,139 --> 00:46:57,659 a huge leap forward in chemistry. It was an early realisation that perhaps there was some 541 00:46:57,659 --> 00:47:02,760 order to the elements, some grand pattern to the building blocks of our world. 542 00:47:02,760 --> 00:47:11,619 And Lavoisier didn't stop there. He created a system to classify the discoveries of many 543 00:47:11,619 --> 00:47:16,780 other chemists and set out to transform the language of chemistry. 544 00:47:17,900 --> 00:47:25,039 He began a revolution of scientific vocabulary, replacing the picturesque and poetic with 545 00:47:25,039 --> 00:47:34,639 precision, so dephlogisticated air became oxygen, astringent Mars saffron became 546 00:47:34,639 --> 00:47:41,780 iron oxide, oil of vitriol became sulfuric acid and philosophical wool 547 00:47:41,780 --> 00:47:48,500 became zinc oxide. At last there was a universal language to identify the 548 00:47:48,500 --> 00:47:54,260 elements. Maybe it's a shame that some of these exotic names have been replaced 549 00:47:54,260 --> 00:47:57,260 But in a way, I admire Lavoisier's logic. 550 00:47:57,260 --> 00:48:00,260 He revolutionised chemistry. 551 00:48:00,260 --> 00:48:03,260 But other revolutions were in the air. 552 00:48:05,260 --> 00:48:11,260 In 1789, the French Revolution would have terrible consequences 553 00:48:11,260 --> 00:48:14,260 for both Lavoisier and his rival Priestley. 554 00:48:14,260 --> 00:48:18,260 In England, Priestley's sympathies for the uprising 555 00:48:18,260 --> 00:48:20,260 gained him unwelcome attention. 556 00:48:20,260 --> 00:48:24,260 Things came to a head in 1791, when an angry mob, 557 00:48:24,260 --> 00:48:28,260 frightened that revolution would find its way to England, 558 00:48:28,260 --> 00:48:32,260 descended on his new home and burnt it to the ground. 559 00:48:32,260 --> 00:48:37,949 Thanks to a tip-off, Priestley escaped unharmed, 560 00:48:37,949 --> 00:48:40,949 but decided to flee to America. 561 00:48:40,949 --> 00:48:43,949 Lavoisier was not so lucky. 562 00:48:43,949 --> 00:48:46,949 Despised for his government work, 563 00:48:46,949 --> 00:48:50,949 Lavoisier and 28 other tax collectors were tried and found. 564 00:48:50,949 --> 00:48:55,869 were tried and found guilty of conspiring against the people of France. 565 00:48:55,869 --> 00:48:59,510 He was brought here to La Place de la Révolution that same day, 566 00:48:59,510 --> 00:49:02,110 May the 8th, 1794, 567 00:49:02,110 --> 00:49:05,829 and in 35 minutes they were all executed. 568 00:49:05,829 --> 00:49:10,269 The next day, the French mathematician Joseph Lagrange commented, 569 00:49:10,269 --> 00:49:13,429 it took them just an instant to cut off that head, 570 00:49:13,429 --> 00:49:17,190 but another 100 years may pass before another like it is seen. 571 00:49:17,190 --> 00:49:22,449 Lavoisier left an incredible legacy. 572 00:49:23,230 --> 00:49:27,869 He'd cast out old dogma and replaced it with an empirical approach. 573 00:49:31,000 --> 00:49:32,539 There was no going back. 574 00:49:35,090 --> 00:49:40,150 Experimentation could now prove or disprove the most radical of ideas. 575 00:49:40,150 --> 00:49:45,110 But scientists were still convinced that more elements must be out there 576 00:49:45,110 --> 00:49:48,650 and were desperate to find new ways of revealing them. 577 00:49:48,650 --> 00:49:59,650 Matter remained fundamentally impenetrable and it would take a powerful and dangerous force to find a new way of splitting it apart. 578 00:50:02,650 --> 00:50:09,650 Enter Humphry Davy, a wild, charismatic Cornish scientist who frequently courted jeopardy. 579 00:50:10,650 --> 00:50:14,650 He was Professor of Chemistry at the Royal Institution in London. 580 00:50:14,650 --> 00:50:20,650 On 6 October 1807, Davy was working away in the basement 581 00:50:20,650 --> 00:50:24,650 where he'd adapted the servants' quarters to make a lab. 582 00:50:24,650 --> 00:50:30,650 He'd been working with some crystalline salts called potash. 583 00:50:30,650 --> 00:50:34,650 Lavoisier had been unable to break it down 584 00:50:34,650 --> 00:50:36,650 and reckoned that it was an element. 585 00:50:36,650 --> 00:50:38,650 But Davy wasn't convinced. 586 00:50:38,650 --> 00:50:42,650 He suspected that potash was made up of more than one element. 587 00:50:42,650 --> 00:50:47,650 But no matter how hard people had tried, potash had defeated them. 588 00:50:47,650 --> 00:50:51,650 There just didn't seem to be any way that chemistry could break it down. 589 00:50:55,650 --> 00:50:58,650 Now Davy had a new idea. 590 00:50:58,650 --> 00:51:01,650 The first electric battery had recently been invented. 591 00:51:03,650 --> 00:51:09,650 It was very simple. Rows of metal plates and cardboard, soaked in salt water. 592 00:51:12,650 --> 00:51:16,130 But it made the world's first continuous current. 593 00:51:16,909 --> 00:51:20,670 I'm going to use the same principle to try to create electricity. 594 00:51:24,400 --> 00:51:28,920 I've got a copper coin connected to a zinc washer via a copper wire. 595 00:51:28,920 --> 00:51:36,019 And if I have enough of these linking up these wine glasses filled only with salt water, then I can create a circuit. 596 00:51:36,519 --> 00:51:45,420 Now, if I connect up the copper coin on one side via a lamp with the zinc washer on the other, I've created electricity. 597 00:51:45,619 --> 00:51:51,300 The lights come on. I've made electricity just from glasses filled with salt water and two different metals. 598 00:51:52,019 --> 00:51:56,380 Most chemists at the time thought that the effect had something to do with the different metals. 599 00:51:57,179 --> 00:52:04,219 But Davy believed there was a deeper reason, that it was a chemical reaction that was causing the electric current. 600 00:52:05,559 --> 00:52:14,119 But if that were the case, then perhaps the reverse could be true, and an electric current could cause a chemical reaction. 601 00:52:15,099 --> 00:52:17,179 Davy resolved to find out. 602 00:52:18,639 --> 00:52:23,519 Chemist Dr Hal Sosaboski and I are going to attempt Davy's experiment 603 00:52:23,519 --> 00:52:26,840 to find out what Davy actually witnessed. 604 00:52:27,119 --> 00:52:28,119 Andrew, welcome to the lab. 605 00:52:28,320 --> 00:52:28,760 Thank you. 606 00:52:30,039 --> 00:52:32,119 Right, so we're going to be splitting potash. 607 00:52:32,539 --> 00:52:34,880 First thing we're going to have to do is melt the potash. 608 00:52:35,619 --> 00:52:38,679 And it's got a relatively low melting point of 360, 609 00:52:38,679 --> 00:52:43,159 which means we can melt it with a Bunsen flame and a blowtorch. 610 00:52:44,119 --> 00:52:53,460 So, almost straight away, we're seeing that glistening of the liquid forming, and it's 611 00:52:53,460 --> 00:52:56,800 melting back into the receptacle. 612 00:52:56,800 --> 00:53:01,960 And this, I gather, in the melted state, is very, very dangerous, very caustic. 613 00:53:01,960 --> 00:53:02,960 Exceptionally so. 614 00:53:02,960 --> 00:53:08,659 If it splashed onto us, it'll be instantly disfiguring, instant blindness. 615 00:53:08,659 --> 00:53:13,300 In the solid state, it's bad enough, but in the molten state, it's really hideously dangerous. 616 00:53:13,300 --> 00:53:16,599 scary then to think what it must have been like in Davies lab you know people 617 00:53:16,599 --> 00:53:20,619 must have been losing fingers and eyes and getting disfigured yes it was an 618 00:53:20,619 --> 00:53:23,260 innocent age in some regards he would have been standing there in his tweeds 619 00:53:23,260 --> 00:53:27,400 and his bowtie with no glasses on but that's the way science was they were all 620 00:53:27,400 --> 00:53:30,760 pioneers and don't forget Davy didn't know what he was looking for so he 621 00:53:30,760 --> 00:53:34,300 didn't know that he was looking for a very reactive metal that would actually 622 00:53:34,300 --> 00:53:41,130 catch fire almost in air so there was a double danger if you will over here this 623 00:53:41,130 --> 00:53:45,929 modern day lorry battery provides 12 volts enough for our experiment um and we've got carbon 624 00:53:45,929 --> 00:53:50,969 electrodes and some jump leads so we're all ready to split our potash and we just don't know what 625 00:53:50,969 --> 00:53:57,849 it's going to do when we put this in the electric current passing through the melted potash is 626 00:53:57,849 --> 00:54:04,409 creating an unpredictable and volatile chemical reaction wrenching apart the electrically charged 627 00:54:04,409 --> 00:54:11,610 particles in the potash but is it enough to split it it's all changed color it's gone all 628 00:54:11,610 --> 00:54:14,489 yes the electrodes are being consumed because it's a very caustic environment 629 00:54:15,289 --> 00:54:20,250 oh look there it is oh is that that pink flash the lilac flash that's where the potassium is 630 00:54:20,250 --> 00:54:24,409 being produced and it's reacting straight away that's the potassium on the surface and it's just 631 00:54:24,969 --> 00:54:29,849 burning quickly in in in oxygen there's another one look yes it's reacting just like a tiny 632 00:54:29,849 --> 00:54:34,329 pink matchstick popping on the surface yeah exactly and that sort of that sort of noise 633 00:54:34,329 --> 00:54:40,090 that was like a match flare is the potassium flaring off wow and that's fantastic that's 634 00:54:40,090 --> 00:54:46,250 what you would have seen just there and then beautiful lilac flame where others had failed 635 00:54:46,250 --> 00:54:51,610 davey succeeded he'd split potash into its most fundamental ingredients 636 00:54:51,610 --> 00:55:02,710 forcing out an element never seen before potassium I can't possibly imagine the excitement that Davey 637 00:55:02,710 --> 00:55:07,269 would have felt he was discovering this new element for the very first time no one else 638 00:55:07,269 --> 00:55:13,010 in the world has seen it his assistant reckoned that Davey did a quick dance around the lab for 639 00:55:13,010 --> 00:55:23,269 few minutes when he when he made the discovery potassium it's a soft silvery metal which can 640 00:55:23,269 --> 00:55:34,670 be cut like cheese for a minute it shimmers like steel then tarnishes in air potassium is essential 641 00:55:34,670 --> 00:55:41,929 to human life our bodies need a constant supply to keep the muscles and kidneys working it also 642 00:55:41,929 --> 00:55:50,010 helps to transmit nerve impulses. But it's a killer too. A large dose of potassium chloride 643 00:55:50,010 --> 00:56:00,679 can result in a fatal heart attack. When potassium touches water, it reacts explosively, releasing 644 00:56:00,679 --> 00:56:12,119 hydrogen and leaving behind potash. But it's abundant as a salt in sea water. It took Humphry 645 00:56:12,119 --> 00:56:21,360 Davy to prize it from nature and make it visible. Davy seemed to be able to penetrate further 646 00:56:21,360 --> 00:56:26,940 into the unfathomable world of the elements, further even than Lavoisier had thought possible. 647 00:56:27,699 --> 00:56:37,869 But potassium was just the beginning. In time, Davy added six new elements to Lavoisier's list 648 00:56:37,869 --> 00:56:41,710 and he confirmed that substances like chlorine and iodine 649 00:56:41,710 --> 00:56:42,829 were also elements. 650 00:56:43,769 --> 00:56:46,230 He was a maverick in the world of chemistry, 651 00:56:47,010 --> 00:56:50,469 fearless, even reckless in the face of a hazardous experiment. 652 00:56:51,250 --> 00:56:53,510 For him, danger was part of the territory 653 00:56:53,510 --> 00:56:56,550 and it was probably the inhalation of all those chemicals 654 00:56:56,550 --> 00:56:59,050 over the course of his life that took their toll. 655 00:56:59,869 --> 00:57:04,130 He died in May 1829, aged 50. 656 00:57:04,130 --> 00:57:13,510 his quest for knowledge to delve deeper into the concealed natural world perhaps cost him his life 657 00:57:13,510 --> 00:57:21,829 but the step he made for scientific progress is immeasurable by the time of davy's death 658 00:57:21,829 --> 00:57:29,230 the idea of the elements was firmly established 55 of our planet's building blocks had been 659 00:57:29,230 --> 00:57:34,670 identified. And the world had a new science. Chemistry. 660 00:57:40,969 --> 00:57:45,530 Next time, I'm going to take up the quest of the chemical pioneers. 661 00:57:45,929 --> 00:57:47,230 While my arm's burning up. 662 00:57:47,429 --> 00:57:50,610 As they struggled to make sense of elemental chaos. 663 00:57:51,750 --> 00:57:57,769 I'll find out how a scientist's dream was to become one of our most beautiful creations. 664 00:57:57,769 --> 00:57:59,809 the periodic table. 665 00:58:00,989 --> 00:58:04,269 And I'll delve into the subatomic world 666 00:58:04,269 --> 00:58:07,510 to reveal the hidden pattern of the universe, 667 00:58:07,989 --> 00:58:10,030 the order of the elements. 668 00:58:18,610 --> 00:58:21,889 And the BBC's World of Wonder season continues 669 00:58:21,889 --> 00:58:26,809 with How Earth Made Us, over on BBC Two tomorrow at nine. 670 00:58:27,369 --> 00:58:30,090 Still to come tonight, though, stay with us for Only Connect. 671 00:58:31,769 --> 00:58:32,610 Thank you.