Program 24 - "Skeptical Chemists"

Music First Woman: "Ah, I am so worried about Madam Cliquot.Her husband, he is still practicing alchemy,reciting incantations and invoking spells.Whereas, in England, they are using science to discover whatthey say are new chemical elements.They are using electricity!"Second Woman: "Monsieur Cliquot won't be doing much of anything for a while.Didn't you hear about the accident?"First Woman: "No, what happened?"Second Woman: "He was trying to turn a fishingweight into a golden pendant.There was a terrible explosion."First Woman: "Oh, mon dieu, was he injured?Second Woman: "He lost three fingers off his right hand.Otherwise, he's fine."First Woman: "Oh!"Well, does that mean that when he recovers he willhave to write his runes in shorthand?"Both Women: "Oh, ha, ha, ha, ha, ha, ha, ah, ha, ha, ha, ha..."MusicSilico: "We are back with Science 122, the Nature of Physical Science.This is the telecourse that emphasizes that chemistryis the most elementary of all the sciences.This is Program 24, Lesson 4.2, "Sceptical Chymists."Before we're done with this program we will have traveledfrom alchemy to chemistry, tracing the contributionsof Paracelsus, one of the weirdest and mostcontroversial figures in the history of science.

We'll study Johann Baptista van Helmont and his study of airand Robert Boyle and his new elemental paradigm.We will get momentarily sidetracked as we study theclever, but incorrect theory of a substance of combustion known as phlogiston.Then we will note the activities of Antoine Lavoisier and hisseminal work which advanced the science of chemistry the wayNewton had done for physics, and set the stage for the discoveryof many new elements early in the 19th century.Here are the objectives for today's lesson.These objectives are also in the Study Guide at the beginning of the lesson.Before you begin to study the lesson, take a few minutesto read the objectives and the study questions for this lesson.Look for key words and ideas as you read.Use the Study Guide and follow it as you watch the program.Be sure to read these objectivesin the Study Guide and refer to them as you study the lesson.

Focussing on the learning objectives will help youto study and help you to understand the important concepts.Compare the objectives with the study questions for the lessonto be sure that you have the concepts under control.Well, it's good to hear from you my silicon friend.You were very quiet the last two programsand I thought maybe you weren't feeling well.Silicon: "I do not feel I am made of silicon.Yes, I have been conserving my energy.Do you want me to talk more?"Well, not really, but I'm sure you will anyway, eventually.Oh, hello, and welcome to Program 24.In this program we're going to consider the transitionfrom alchemy to chemistry.We want to do that by looking a little bit more closelyat the alchemy so we can see the differences between alchemy and chemistry when we get there.Remember that the whole idea of alchemy was basedupon Aristotle's theory of form and matter whichled logically to the belief that every chemicalchange was a transmutation of some sort.This is not surprising, if you think about it.Because from our definition of chemical change,we saw that the chemical reaction produces completely new products.That are completely different from the reactants that were originally there.In the alchemical method of looking at things,nothing remained of the old substance,except a "virtue" or some sort of hidden quality.

Remember now, that the properties of matterfor the alchemists were thought to be due to what we might call"substantial forms and real qualities" which were believedto be actual entities which were attached to the matter.For example, a substance was white because itcontained some "form of whiteness."So, in the alchemical schemes, substances were endowed with personality.They loved and hated, for example.They had affinities for each other.Certain chemicals liked each other and didn't like each other whichdetermined whether or not reactions would take place.So, in the 17th century, we've already seen in an earlierprogram how the 17th century was a ripe period of change.This is true of chemistry and alchemy as well.In fact, the 17th century saw a very rapid growth of chemicalknowledge as well as physical knowledge as the old ideas were challenged.

The first half of the 17th century, as far aschemistry goes, was a period of increasing precision.What this means is that quantitative studies cameto chemistry, much the way they did to physics.The people began to realize that matter is essentially indestructible.That it simply doesn't disappear and go away.And things like the nature of acids and bases and their reactionsand their salts began to be understood.And we've already mentioned that the first scientific societiesallowed results and methods to be reported.So, at this point the theoretical development of chemistry wasin a chaotic state, and every chemist had a theory of matter.The problem was that most of these were not very goodtheories, and most of them did not survive the 17th century.The theories arose, of course, because of challenge to old theories.And remember, that during this time there was a blossomingof the people who were interested in science, so that now,all of a sudden, everybody is getting into the game of practicing science.So, what really happened was that new discoveries demandeda much better explanation that was offered by the occultand mysterious forces of the medieval period.

A new paradigm arose during the 17th century.This is a paradigm of purity of substance.And early in the 18th century, electricity enters chemistrywhich allows us to do lots of things that we couldn't do before.This coincided with the rapid expansion of knowledgein other areas, not just in the sciences but alsowithin other areas, the social sciences, even.For example, many substances which were thoughtby the ancients to be elements were shown not to be elements at all.And many things which were not considered to beelements, were shown to be elements.In fact, in the 18th century, 15 new substances werediscovered that were elements, and in the 19th century,25 more things were discovered that were elements.So, rather than simplifying things, the science of chemistryactually added more and more elements until now,we're sitting up here around 105 or something like that.

Now I want to consider one of the, probably most famous of all the alchemists.His name is Paracelsus.He was born right around the end of the 15th century and his realname is really a trip, we'll have to give you this real name.His real name was Phillippus Theophrastus Bombastus von Hohenheim.I'm not kidding about that.That really was his name.He called himself Paracelsus to indicate his superiorityto the 2nd century Roman physician and writer whose name was Celsus.So he calls himself Paracelsus, indicatingthat he's better than this ancient guy.He was actually a Swiss physician, but he was alsoan alchemist, a mystic and a drunk.In fact, he spent most of his life of the floor of taverns,and it was he, actually who coined the word, "alcohol" for distilled spirits.So it's sort of like the drunk's drunk, if you want to think of it that way.He promoted the use of specific remediesand authored many medical and occult works.We didn't go into the history of medicine in this, but in the oldtimes, the old physicians, Galen was a very famous Greekphysician, who advocated sort of natural causes and, or natural remedies.So Paracelsus formed a branch of medicine that today we wouldcall "iatrochemistry," which means chemical medicine.So he stressed the use of chemicals to cure disease.I think you can see his influence is still carried on to us todaybecause our medical profession today largely stresses chemicals.His views, although they were weird, brought him closerto the modern concept of chemistry than anyone before him had come.

Paracelsus was no doubt the most controversial and certainly theweirdest figure in the history of medicine and chemistry.He was, well, for one thing. he would publicly burn the works of Galen.Galen, again, was the famous Greek physician.And he'd go and put on demonstrations where he wouldburn the works of Galen and do incantations and say that hehopes that Galen's soul is roasting in hell the sameway this paper is burning, and so forth.Basically he did this to show his contempt for the orthodox medical opinion.Don't get me wrong here.I'm not advocating that this is a good kind of behavior.It's just that what we have here is the genius of an uncontrolledmadman, running around Europe in the beginning of the 16th century. So, he considered the views of Aristotle as well as Galento be those of heathens and heretics; considered them to be very uncivilized.He was known for his original ideas, but he was also knownfor his incredible temper, and he had a way of getting in fightswith people and yelling at people and doing all kinds of really bad things.So what he did basically was to wander all over Europe,engaging in stormy controversieswith physicians who followed the theories of Galen.He'd go into a tavern, find a local physician and have thisargument with him and get really steamy, get really mad,get drunk, fall on the floor, and go to sleep.The next day get up and do it again someplace else.

One of the things that bothered people was that he lecturedin the vernacular German instead of in Latin which was veryunusual for physicians of that time, or any time, in fact.He aroused such violent opposition amongst the people of Europethat his writings could not be published for 20 years after his death.The very mention of his name in legitimate circles in Europewas enough to rouse the ire of anybody who's educated.His writings are the writings of a drunk.They're marred by mysticism, they use strange terminologyand have a very confused style of writing.And in many cases, it's not all together clear exactly what his ideas were.So you may be wondering at this point, here's this, this dementeddrunk who goes around offending people, but yet, why do weconsider him a genius and allow him to be includedhere in this history of scientific idea?The reason is that his main ideas were very clearlyoutlined and well established.And he, for example, took the attitude that alchemy wasreally a science and what it meant was any process in whichnatural products were made fit for a new end.That is, any chemical changes, in other words.He considered processes such as work in ironand baking bread to be within the realm of alchemy.Former alchemists had not done this.They were entirely concerned with mystical incantations.He also held that the macrocosm,which means the universeat large, and the microcosm, which means individual people,behave similarly, so he considered, for example,digestion to be an alchemical process.He said that human digestion was controlled by a spirit,an alchemical spirit which he called "the Archaeus."And, basically, what the Archaeus did wasto perform a separation in the digestive tract.

The Archaeus separated poisonous substancesfrom nutritious ones in the body.So, he thought, then, that the most important goal in alchemy wasthe preparation of medicines which he called "arcana."Some of these words you may have heard, so he called these thingsarcana, which could restore the bodily balance disturbed by disease.In other words, inside your body, you've got this creature, spirit,called Archaeus, and if you feed Archaeus the right things, then Archaeus will do his job.And if you don't feed Archaeus the right things,then you'll suffer digestive problems and disease.So the next time you have indigestion, don't reachfor the Tums, just do an incantation to Archaeus.He also, Paracelsus did, subjected large numbers of metals to a standardized set of reactions.What he means by this is he took all the known metalsand did the same things to each of them.Dissolved them in the same kind of acid, heated themto the same temperatures, and this is something that hadn't been done before.

Now Paracelsus grew up in a mining district so he had a goodknowledge of metallurgy, and what he did by thesedissolutions is to obtain a series of salts in solution.He called them "oils."Again, I said he had a weird terminology.What he did then was to generalize chemical reactionsinstead of considering every process as an individualtreatment of a separate substance the way previous alchemists had done.So, he generalizes the idea that you can do the same kindsof chemical processes to different kinds of things.In doing so he also increased the number of remedies available for his patients.Although it turns out that some of these remedies were distinctlydangerous to the patients and he killed more than a few peopletrying out these remedies on people.So, the whole science then of the iatrochemistry,that's "I A T R O," iatrochemistry--using chemicalsfor remedies-- stronglymodified the older theoriesof medicine, and he actually had a great influence ont he practiceof medicine, even though he was giving poisons that weren't tested.You know, today, of course, a new medicine has to be tested veryrigorously before it's released, just for this reason.His ideas encountered strenuous opposition by physicians of the time.I think you can imagine why.Right?He was a quack, or at least he was considered a quack.But, after his death, his ideas were spread by a large groupingof followers which actually sort of spooled off a new branchof medicine without the use of chemistry.So, he also made, in addition to this practical contribution,a very important theoretical contribution which has to dowith the nature of chemical elements.

You may remember that in the last program we talked about thiscombination of sulfur and mercury, as sort of a Yin, Yangprinciple with sulfur being the active principle and mercurybeing the passive principle, and these things combinein the womb of mother earth to create metals.What Paracelsus did was to add salt to this as componentsof metals along with mercury and sulfur.You can see here this forms a nice little triad.Because now you've got mercury, sulfur and salt, there's three things.And remember in the Christian theology there's the Father,the Son and the Spirit, the Holy Spirit.There's a triad there.And there's also the concept of the soul, the spirit and the body.So, not only that, but the three states of matter, gas, liquid and solid.So you have this nice medieval sort of Pythagoreannumerological thing going on with these threes.OK.So, he added the body, you might say, to create the triangle.Can you see this that one of these, the gas, liquid and solid?What he's done here is to add the solid, salt, as a primary element of matter.He also called air, "chaos."

The word chaos means disorder, and it's actuallythe root word of our present word, gas.By Paracelsus' time the air had given way as a prime element to fire.So fire was considered at this time to be the prime element.So, sulfur in Paracelsus' system embodies fire, whereas mercuryembodied liquidity and salt embodied earth.So here you have a nice mixture of things because when woodburns, as Paracelsus said, that which burns is sulfur,that which vaporizes is mercury, that which turns to ashes is salt.Now this whole idea, this triad of substances fit in so wellwith observations that it completely replaced the sulfurmercury theory by the time that Paracelsus had published his material.

Now, by the way, I want to point out here that Paracelsus stillconsidered the four elements of Aristotle as basic, even thoughhe thought that Aristotle was a heretic.He placed little emphasis on them though.And, he emphasized that his sulfur, mercury and salt werenot the common substances themself, but rather,they were the more abstract essences of these things.So what the means, that the four elements appeared in bodies asthese three principles, of salt and mercury, and that eachsubstance had its own kind of sulfur and its own kindof mercury and its own kind of salt.So, salt, for example, he saw as the principle of fixivity and incombustibility.In other words, it's earthiness.Mercury was the principle of fusibility and volatility.In other words, it's the principle of metalness.And sulfur, of course, is the principle of combustibility.Because sulfur burns with a nice clear blue flameand I'll illustrate that for you in a minute.So, in Paracelsus' theory of things medical substances like thechemicals that he used were composed from the fourelements which formed receptacles or matrices for the universal qualities.Understand what I mean here?It formed matrices for the four qualities much in the same waywhich Aristotle had claimed that his four elements weresuperimposed like on a clay tablet.Paraclesus called this the "tria prima" or the three prime qualities.

I have a quote here from Paracelsus, which, I like this quote."The world is as God created it.He founded the primordial body on the trinity of mercury, sulfurand salt, and these are the three substances of whichthe complete body consists.For they form everything that lies in the four elements.They bear them all the forces and faculties of perishable things."That's Paracelsus' description of elements.Of all of the people who we've considered in this alchemyto chemistry transition or who we will consider,Johann Baptista van Helmont actually is the one whostraddles the fence and represents the realtransition from alchemy to chemistry.He was a Belgian, influential and highly respected physician,who had many erroneous theories, like lots of people did at thistime, but had a great influence on later chemists.He was a much nicer character than Paracelsus, believe me.The harsh criticism of the controversial medicineof his time by people like Paracelsus and his followers,made him many enemies and also retarded the general acceptance of his views.He was, in fact, denounced as a heretic by the SpanishInquisition and spent most of his life under house arrestin a form of retirement, very much like what happened to Galileo,except that he was much, Baptist van Helmont was much younger than Galileo.Spain, but the way, was in control of what is now Belgium.His posthumous writings brought him fame, much like Paracelsus.

One of the things that sort of stands about Helmont is that he,among almost no one else claimed to do this, claimed to havewitnessed an actual transmutation of base metal into gold.Now whether he was smoking something from the garden thatday or whether he really believed he saw it, we will never know.But, he was actually a disciple of Paraclesus, but like manydisciples, he disagreed with him and modified thetheories quite some, quite a bit.In fact, Helmont called himself a "philosopher by fire."He was strongly anti-Aristotelian and rejected the four elementsof Aristotle, but also rejected the tria prima of Paraclesus.Boyle said of him that "he was an author more considerablefor his experiments than many learned men are pleased to think of him."Meaning that he didn't have the reputation that he deserved.He was one of these people who believed that fire was theprimary elements, although he thought that the matter,all matter, which he called bodies, had two first beginnings.One of which was water and some sort of an active organizingprinciple which he called a "ferment."I'm sure you've heard the expression "let your ideas ferment."We also use the word, ferment, of course,in terms of producing alcohol by fermentation.But the word, ferment, in this sense means an organizing principle.The other element that was important in this was air, which was purely physical.Whereas water could be molded into the variety of substanceson earth, air was sort of a neutral element in this.

Fire, in Helmont's view, was a transforming agent, not an element.In other words, fire was a ferment, which is why hecalled himself a philosopher of fire.So, basically, his theory was that earth was createdby the action of these ferments on water.Now, I mentioned before that many of the experiments that weredone in medieval times were done to support an already existing idea.Helmont actually did a very interesting experiment.What he did was to take a bunch of dirt and weigh it, plant a treein it, and very religiously and carefully water the treefor five years, add nothing else but water, then at the endof five years, he uproots the tree, shakes all the dirt off the roots,and weighs the remaining dirt after it's dried and finds thatthe tree gain 160 pounds, but the weight of earth remained exactly the same.So, what was his conclusion?Well, his conclusion was, of course, that water turned into wood.That's all he gave the tree for five years, after all.

Now, today, of course, we understand that mostof the mass of the tree comes from carbon dioxidein the air, rather than from the soil.But that was unknown in those times.He did recognize that air was not an element, but rather a mixture of gases.And he also did a very interesting experiment making somethingcalled water glass, which he also used as a way of proving,or I should say, supporting his theory that everything was made from water.What he did was take a small amount of sand and fuse itwith a chemical called alkali, just sodium dioxideto form a substance called water glass.It's called water glass because it looks glassywhen it's solid, but it dissolves in water.And the water glass liquified when you expose it to airbecause it absorbs...today we would say that it absorbs moisture from the atmosphere.Obviously, Helmont said, a conversion of earth into water.Sand is earth.You leave it out and you mix it with this stuff, leave it out, it turns to water.The water could be reconverted to earth by treatment with acid.In other words, you treat the stuff with acid and the waterdisappears, the reaction goes in reverse and you wind upwith exactly the same amount of silica that you had before.

So, Helmont used this as a way of proving that water was the primary element.His thinking was much more modern than his predecessors.Even though he still falls into this alchemical idea.For one thing, he used quantitative measurements, he weighed things.He did this routinely, not just in special circumstances.He also hinted at the fact that conservationof mass existed, that mass couldn't be destroyed.So, his theory of the elements was basically that when waterevaporates, it gives rise to anair-like substance.In fact, so do many chemical reactions.In other words, they give off gases.These things could not be air because air was a primaryelement, so they must represent a new class of materials.The product of evaporation of water which today we know assteam easily returns back to water so van Helmontconsidered it to be a type of vapor, when it can betransferred back and forth between a gas and a liquid.Other substances are more permanent so he gave them a name.The name he gave them was "gas."Coming from the word, chaos, that Paraclesus had used for air.Notice here the use of the word.Now we take this so much for granted that matter had thesethree states and that air is gas, it's hard to believe from ourparadigm that there was a time when people didn't know about gases.But, in Helmont's scheme, gas was a subtler thingthan a vapor, but denser than ordinary air.And see, what he was thinking of here now isthat chemical reactions can produce a gas.In this sense, powerful enough to explode a closed gas cylinder.You do a certain reaction inside a closed gascylinder, seal the gas off, the gas will explode.So, he used this to explain the effects of gunpowder.And then went on to explain the same sort of thing asresponsible for earthquakes and lightening and tsunamiand all these other sort of violent events that take place on the earth.Very interesting guy, very clever, still medieval,but just straddling the fence on his way to becoming a chemist.

So now we come to Robert Boyle who was theoriginal and perhaps the first sceptical chemist.Boyle was one of these people who was a contemporary of Newtonand Hooke and Wren, who actually was the founderof the Royal Society of London.You may remember the story about Newton and Hookeand so forth in the Royal Society.He was independently wealthy.He didn't have to work for a living, and spent a lotof time simply practicing science.He's one of those people who became enamored of the hobby of science.One of the things that he did, along with other people in histime--you notice here the time period is spanning Galileo'sand Kepler's era--is that he performed experiments,rather than just observing and speculating about things.One of the things that Boyle's well known for is the gas law thatbears his name called Boyle's law which relatesthe pressure and volume of a gas.And we'll look at this a little bit later on in another program.

Boyle's main contribution here is two things:First is that he worked to establish a mechanical theory of chemistry.Along with Newton.You may remember that people were trying in Newton's timeto come up with an explanation for how you can explain the lawsand principles of chemistry from a mechanistic pointof view in a Newtonian paradigm.And Boyle was one of those people who wanted to work toward this goal.His most famous work is a book called,"The Sceptical Chymist," the title of our program.This was published in 1661 when Boyle was in his 40s.This is basically a dialogue between supporters of the oldertheories and Boyle, himself, much in the way that Galileo hadwritten a discourse on the two new sciences.But these were people who needed, the other people were peoplewho needed to be convinced by more than medieval speculations.In other words, they wanted some science in here.What Boyle did was present very convincing arguments designedto destroy most of the former beliefs about the propertiesof matter and about alchemy and the mysticism and the spiritualism.

One of the interesting things about Boyle is that he did notpresent a substitute for the ideas, and this is why he was calledthe Sceptical Chemist and many people have criticized himfor simply criticizing the old ideas without comingup with any new ones himself.Which led some people to believe that he wasnothing by a sceptic and not really a scientist.But, one of the things that Boyle did was supportedthe corpuscular theory of matter.In other words, the idea of matter being made up of small particles and atoms.What he conceived of were small, solid, physically indivisibleparticles that were the building blocks of nature.These, he said, were associated into larger groups which oftenacted as units through a number of chemical reactions.In other words, he's talking very much about the things todaythat we would call atoms and molecules.The size and the shape of these units according to Boyle gavephysical properties to the substances, but their motionwas equally important, and a change of motion resulted in a change of properties.When we get to the later aspects of kinetic theory and atomictheory, you'll see that he was right on with this.Without being able to define the things quantitatively, he was right on.He also stated that the attraction and affinity of elements wereexplained by the mutual fitting together of these moving particles.In other words, he was also talking about a theory of chemical bonding.Some of this was borrowed, of course, from Democratusand the ancient Greeks, but a lot of it was very modern sort of stuff.The thing that we really give Boyle most credit for,and even historians have some disagreement about this wasthat he defined for us the modern view of an element.

Now it's interesting that he did this although he still believedin the idea of transmutation and some of the alchemical ideas.Much like anybody who we've studied.Even though you have new ideas that look forward, you stillcan't quite give up with the old ideas.One of the things that Boyle failed to do was still to make theconnection between these corpuscles of matter and the purity of elements.Again, between atoms and elements.But here's what Boyle said, "I now mean by elements certainprimitive or simple or perfectly unmingled bodies,which not being made of any other bodies or of one another,are the ingredients of which all those perfectly mixed bodiesare immediately compounded and into which they are ultimately resolved."What?More of this old obscure ancient English writing here.What he's saying is that elements are simply thesimplest types of chemical material."Certain primitive and simple are perfectly unmingled bodies,not being made of other bodies or one another, and theiringredients of which all other bodies are made."So, what's he's doing is defining the conceptof element as a puresubstance.A substance that cannot be broken down into a simpler substance.Now it's interesting that this did several things.It, first of all, began the dialogue on our modern concept of anelement, and it started people thinking about an element in those terms.Much the same way that Galileo had donewith motion just a few years previously.He also dispelled the alchemist's notion of an element as thisspiritual quality that substances possess.He, you might say that the idea of elements as purityof substance replaced the concept as the substance as a "purveyorof elemental principles," such as liquidityand metalness and that sort of thing.

The other thing that's interesting is that Boyle began with thisdefinition of an element, a paradigm, single handedly,and it's very unusual that somebody can simply make astatement and with that statement change an entire way of thinking.Newton, remember, had to go through a lot of trouble to change the paradigm.Boyle gave no new candidates for elements.In fact, he was not even clear on howto distinguish elements from other substances.He had no clue about how to determine whethersomething was unmingled or mixed.He listed no possible candidates, and in the 17th century thetechniques were so crude that it's not likely anybody would havebeen able to discover them anyway.And many of the things that people considered to be elementsat the time, like water, for example, were really compounds.So, the big question remained in Boyle's time, "How could achemist decide whether or not a particular materialwas unmingled or whether it was mixed.

Next we want to consider a bad theory of chemistry,or maybe I should say, an incorrect theory of chemistry.The theory of philogiston.In the 18th century chemical interests or the interestof science in general turned to the nature of combustionand the forces that held chemical compounds together.I'm surrounded by these burning candles, and one of the firstthings we think of when we see candles is what's the occasion.We use them for birthdays.We use them, people use them in occult practices.We use them for religious purposes.There's something about fire that invokes this curiosity.It always had in people, I think.So, it's obvious that when combustion occurs,that fire is somehow escaping from this burning object.How it escapes, exactly what's going on is a mystery,unless we already have built into it, like most of us do,a chemical paradigm that explains combustionin terms of a chemical reaction.Well, back in the 17th century, the same sorts or questions were asked.But without knowing about the existence of oxygen,the existence of organic compounds, the chemicalreactions, the existence of energy, and so forth, this is really hard to figure out.So, what they came up with was this ideaof the substance called phlogiston.The history of this is a little long and complicated, so I don't wantto get into the details of exactly who came up with the theory.But it had to do with the substance of earth.And it became apparent that there's more than one kind of earth.So, phlogiston was thought to be the combustible type of earthwhich is contained in all matter.There's an analogy here between combustion, which is theburning of organic substances like the waxand the candles, and calcification.We get the word, calcium, from that term because calcium alsoburns in air to produce a white calx.

The word, calx, was used to indicate any sort of a reactionproduct of a metal which was burned in air.So, the idea grew very slowly that air was needed for combustion to occur.Now, combustion ceased according to this whenair became saturated with phlogiston.And it works something like this:All substances were thought to contain phlogiston.Some substances which are combustible had morephlogiston than others, so fire was in line with the principlesof van Helmont was considered to be an agentwhich released phlogiston into the air.And so, what the process of smelting a metal is actuallythen the process releasing phlogiston from the woodand giving it to earth or the calx, in other words, leaving behinda metal which is phlogiston rich.In other words, the process of combustion was consideredto be a process of removing phlogiston from the combustiblesubstance and putting it into the earth.It's kind of an interesting theory, if you think about it that way.So, the idea is then that smelting ores infuses them with phlogiston.So, there's also a phlogiston cycle involved here.Because it's obvious that combustion and these typesof processes will cease when a substance runs out of phlogiston.And in the early theories, phlogiston was removedfrom the air by plants, which were then eaten by animals,which were then given back as organic substances, although not by that name.In other words, there was a phlogiston cycle going on.It was very similar to our modern cycle of carbon dioxide and oxygen.This also explains the calcination of metals which is actuallythe reverse of the process of smelting.

So, in the process of calcination, the metal, which is phlogistonrich gives up phlogiston to the air and becomesan earth or a calx which is phlogiston poor.The same thing also goes for explaining the process of combustion.Because combustion was simply seen as a phlogiston richsubstance like wood, giving up phlogiston into the air whichresults in ashes which is basically the wood minus its phlogiston.This explains a lot of different things.It explains acidity and alkalinity.It explains the colors and odors of plants.It also explains things like chemical reactivityand the composition of various organic substances.The role of carbon or charcoal in this was very central because,as I mentioned earlier, the process of smeltingusually involves the carbon from fire.The carbon before the ashes appear from the fire.

Phlogiston was thought to be embodied in carbon becausecharcoal or coal burns almost completely, not entirely,but almost completely, leaving behind only a small amount of ash.So, the early phlogistonists believed that carbon,in the form of charcoal, was nearly pure phlogiston.So, you see the idea here?You have the carbon, which is nearly pure phlogiston whichin reaction with a metal, which is phlogiston poor, gives up itsphlogiston, and in the process it becomes ashes.The metal takes on the phlogiston and now becomes a newsubstance which was known as a calx or an earth.OK?There are several problems with this.One of the problems is that it's obvious that heating metals causes a weight gain.That is, that the calx is heavier than the metal.So, in the phlogiston theory, if phlogiston represents asubtraction of something from the calx, then you have a problemof trying to explain why it is that the calx of the metal is heavier.Does that make sense?So, if you have heating metals creates a calx which is heavierthan the metal, but at the same time the phlogiston theory saysthat the process of calcination is removing somethingfrom the metal, then you have a problem.

The early phlogistonists answered this very simply by saying thatweight is simply a physical process and this is a chemical change.And the two aren't connected at all.Physical processes and chemical processes are completely separate.This idea of weight change was not so obvious to 17 and 18 century chemists.And also, the methods of heating the metals in those timesto obtain the calx involved the use of a lens with sunlight.Everybody, I'm sure, has burned somethingwith a lens at one time or another.The high temperatures which were attained in this lens actuallyevaporated some of the calx and caused it to disappear,making it appear that the weight gain was less than it was.The real problems arose with this theory not until the 1760s,the middle of the 18th century when the gaseous state was studied.So, until that, the phlogiston was thought to be, exist as a sortof incorporeal, non substance, etherial sort of firewith negative weight and sometimes it's simplycalled the lightest known substance.So, it turns out that like many bad theories, there were simply toomany problems with the phlogiston theoryand this signaled the eventual end of the theory.

Now it's time to turn our attention to the individual whomore than anyone else owns the title, the Father of Chemistry. This is Antoine Lavoisier.Lavoisier was one of those interesting characters who wasso involved in political things that he lost his life, in fact,not for his science so much, but for his political activities.He happened to be alive during the time of the French Revolutionand formed an unfortunate association with a company thatwas organized to collect taxes for King Louis XIV.You may remember that King Louis XIV and his wife,Marie Antoinette, lost their heads in the guillotineduring the French Revolution as examples againstthe aristocratic abusers, I guess you might say, of the people.The same fate was suffered by Lavoisier.He died at the hands of the guillotine because therevolutionaries considered him to be of no use to the New Republic of France.And like many of the other people who were executed at this time,his headless body was buried in an unmarked grave.

Lavoisier did many things to establish what we mightsay today, the science of chemistry.And he does very much earn the title of the Father of Chemistry.Among other things, he showed conservationof mass in chemical reactions.I think I need to get rid of some of these, this fire.Let me get rid of (blow, blow, blow, blow).See if I could blow those out on my birthday, then all my wishes would come true?And, I was just thinking, if I had a scale, I could show you what wemean by conservation of mass, but I didn't bring a scale.Maybe I can conjure one.Wait, let me try this.(Deep breath.)OK.(Mumble, exhale, snap).Oh, it worked.That's amazing.Well, now we have the scale here.Let's take a look at the scale and see how it works.I'll show you how conservation of mass works.So this scale is a digital scale.It's a little more modern than the one that Lavoisier invented,and I will show you an example of one like the one he invented a little later.This digital scale is very sensitive.In fact, it's reading right now 22.674 grams,reading down to one one thousandth of a gram.If I conjured this thing correctly, I have some stuff inside it.Ah ha, there it is!You notice that when I open the lid that the numbers start to change.You can see the numbers fluctuating back and forth here.This scale is so sensitive, in fact, that the small air currentsin the room cause the weight to change very radically.In fact, if I even waved my hand across it like this, you can seehow the weight goes up, and how the weight changes.So even that small amount of air current is enough to offset it.So, when we use a scale like this, we have to weigh things with the lid closed.So, let's go back and make sure we have the reading.It's 22.674, fluctuating back and forth between 4 and 5.Let's call it 675.What I want to do is to burn this piece of magnesium that'sin here and see if it gains weight like it's supposed to.

The process of calcination, remember, is a process of gaining weight.This was established by Lavoisier and others in his time.So, let's see what happens.I'm going to pick this up and I'm going to hold on to this while it burns.So the magnesium...I did this once before and it burns with a verybright white light, so don't be shocked when this starts to take off.So, here we are.We're burning it.Look at all that smoke.Ah, see the smoke coming out of there?Oh, let's see, that's really bright.That's really neat.I love this stuff.OK, so when it's done burning, I'll drop all thecalx back into there, turn off the torch.Now, let's weight it and see if it lost or gained weight.The reading on the scale is 22.613.What did we start with?It was 22.674.Wait a minute.It was supposed to gain weight.What happened here?What's going on?So, why did this thing not work?The answer actually is very simple.I pointed out when the reaction was taking placethat lots of smoke of being given off.So even though, in principle, the calx of the magnesium,or the magnesium oxide weighs more than the magnesium metal,there was substance lost from the reaction through the smoke.There was also material clinging to the tweezers and so forth.

Now I used this very accurate scale simply to point out to youthat using very accurate equipment doesn't necessarilyguarantee that you'll get the results you want.You still have to put some thinking into it.It's like saying that a computer won't give yougood results unless you know how to use it.Lavoisier was a person who knew how to use this.Now, he didn't have a digital scale like this, but he didinvent a fairly accurate scale.I think I have one over here.Let me get rid of these burned out candles.This is not exactly Lavoisier's scale,but it's a scale like the one Lavoisier invented.I'm sure you've seen these before.This is called a beam balance and it's simply based on the principle of the seesaw or the lever.And what it does is, when you put something in here, it weightsdown the lever, and you can move weights around on the side overhere to cause it to balance and it's got a calibration on the scale.This particular one also has a dial which allows youto dial in the weight very nicely.

The scale that Lavoisier made was a triple beambalance where there were three different beams.Where each successive beam of the scale had lighterand lighter weights sliding down it.His scale was accurate to five ten thousandths of a gram.In other words, his scale was actually more accurate than this digital scale is.For those of you who don't know how much five ten thousandthsof a gram is, it's enough to distinguish the weight of aboutone, one hundredth of a small drop of water.So, the point of this is that Lavoisier was ableto make very, very detailed measurements.But, as we've seen here, just making the detailedmeasurements doesn't help.Because you have to be able to capture all of the products of the reaction.This is more difficult with burning of wood than itis with the burning magnesium.Because with the burning of wood you have water vapor given off,you have carbon dioxide given off, you have otherconstituents that are actually more gaseous.

So, Lavoisier was able to capture all of these constituentsand was able to show that although some things appearto gain weight when they burn and other things appear to loseweight when they burn, if you can capture all of the reactantsand all of the gases and everything that's givenoff, you find that no mass is lost at all.That if you do combustion in a closed container, after its doneburning, it weighs exactly the same as it did before it was burning.So, from this he created or stated, I should say, what we now knowas the principle of conservation of mass.Which, like our other conservation laws, simply says that massdoes not change during chemical reactions.In other words, the mass of all the products is equalto the mass of all the reactants.Now, what this means, of course, as far as the transitionfrom alchemy to chemistry goes, is that you can't create or destroy matter.The alchemists had thought that you, when thingsdisappear, they simply vanished.But we know today that you can't do that, despite mylittle trick here with the scale a while ago.That matter is not created from nothing and it can't disappear into nothing.That what happens during a chemical reaction is thatmatter simply changes form from one form to another.

We'll also see in the next program that this also sets the stagefor the invention, if you like to use the word, of the atomic theory.Because it sets the stage for being able to say that if matteris made out of corpuscles or atoms, all that happensduring chemical reactions is that the atoms are rearranged.Much like taking things out of one box and putting them into another.You don't lose anything in the process, you simply rearrange things.Lavoisier's experiments, being able to show that mass isconserved in chemical reactions, also allowedhim to disprove the phlogiston theory.He was able to free our thinking from the phlogiston theory.Now, before we go into this in detail, I want to point out thatthe phlogiston was actually discovered as a resultof the process of combustion as I mentioned earlier.And it's easy to show that air has a limited capacity to absorb phlogiston.

You may remember that the phlogiston is given offinto the air and the air absorbs it.If you burn a candle inside a closed container,floating the candle inside water inside a closed container,you'll see that the water rises inside the container.It rises exactly one fifth of the volume.In other words, phlogiston appears to be ableto absorb but one fifth of its volume in phlogiston.People began to wonder why one fifth.And today, of course, we understand that this is becausethe atmosphere is about one fifth, 20% oxygen.And when the oxygen is gone, the combustion stops.But, Joseph Priestly was an English chemist who discoveredwhat we now today call oxygen, but like many other peoplein science what he discovered was somethingdifferent than what he thought he had.What Priestly thought he discovered was whathe called dephlogisticated air.In other words, he found this gas that was given offby the heating of mercuric oxide that when you put itinto a closed container and did the same thing he did with ordinaryair, that it had a capacity to absorb all phlogiston.In other words, it had no limitation on the amount of phlogiston it could absorb.

Priestly thought that he had discovered air from whichall the phlogiston had been removed, so that it now hadan infinite capacity to absorb phlogiston.Another one of those Christopher Columbus kind of things.He was in someplace and knew he was someplacedifferent, but didn't know where he was.There was a controversy, and it still exists in manyplaces, as to who actually discovered oxygen.Whether it was Priestly or Lavoisier.The encyclopedia will say Priestly because Priestly discovered it first.But, like Columbus and Amerigo Vespucci, it was Lavoisierwho recognized where he was and recognized thatit was actually a substance known as oxygen.So, let's go to the graphics and see exactly how the twoof them came up with their separate theories and what thedifference was between Priestly's dephlogisticated air and Lavoisier's oxygen.On the screen is a picture of the apparatus of Priestly.And basically what he did was to heat mercuric oxide.

Now mercuric oxide is a naturally occurring calx that occurs as anore, but the alchemists found to be very useful because it's theonly naturally occurring metallic ore that gives up its metalwithout the presence of a reducing agent like carbon.Not only that, but if you heat mercuric oxide at a hightemperature, it reduces to metallic mercury and drives off this gas.And if you heat it at a low temperature, if you heat themercury at a low temperature, the reaction happens in the reverse.So this is one of these reactions that's a reversible chemical reaction.Very unusual in chemical reactions, but it's one thatpeople are aware of and were used this way.So, what happens is that Priestly heats the mercuric oxideand the affluent which is the gas that's given off is collected under water.So here is a cylinder that's inverted so that the gas bubblesinto the cylinder, the gas bubbles up to the topand it pushes the water out the bottom.

Priestly theorizes that what he has done is removed the phlogiston from the air.In other words, he's removed phlogiston from the air in the cylinder.He then theorizes that he has increased the ability of the airto absorb phlogiston and, sure enough, if you take this gasthat's collects in the cylinder, and thrust a glowing wooden splintinto it, the splint will spontaneously burst into flame.In other words, the gas that's in here supports combustion.I want you to notice that this experiment is qualitative.There's no attempt to measure how much of this gas is givenoff compared to how much is lost over here.So, it's a qualitative experiment.Priestly simply determining that something is happeningto the air over here, and what he's saying is that he's removingthe phlogiston from the air by this process.So, keep in mind that in the process of combustionwith phlogiston, phlogiston is a process of removalof a substance from the original substance.In this case from the mercury oxide or the mercury calx.

Lavoisier took a slightly different approach to this.In fact, Lavoisier did a quantitative experiment.He did the same sort of experiment, only he useda furnace where he could control the temperature.So that he could cause this chemical reactionto proceed first forward and then backward.So what he did was to heat the mercury in this container.He starts with the mercury instead of the calx.Heats the mercury in this container.The volume of air in the cylinder over here decreases.In other words, the reaction works in reverse.So, water is drawn into the cylinder.Though the volume decreases at the same time,the mercury calx forms over here in the retort.When the calx stops forming the heating is stopped.So what happens is the mercury changes to calx.It takes air out of this container and the mercury changes to calx over here.Lavoisier weighed the entire thing.So, he notes over here that the weight of the mercury plus thecalx is exactly, shows the same weight gain as the cylinder has lost.You get the picture here?In other words, something is being takenfrom the cylinder and added to the mercury to form the calx.

The mercury plus calx weighs more than the mercury.The air in the cylinder is exactly equal to the gain in weightof the mercury when it changes to calx.So, the remaining air inside the container does not supportcombustion and it, the air exactly that's lost from the containeris exactly one fifth of the volume of air.In other words, the reaction takes one fifth of the air, combines itwith the mercury and the weight stays the same.The remaining air does not support combustion.So, now, Lavoisier takes the calx that was heatedand repeats Priestly's experiment.He heats the calx, drives off the accumulated volume of air.That causes the volume of air in the cylinderto become larger, pushes the water out.Once again, the weight gain now in the cylinder is exactly the sameas the weight loss in the retort, and the remaining air now supports combustion.You see how the experiment is quantitative.So what he is doing is, in modern terms, we would say he's takingoxygen out of the air, reacting the oxygen with the mercury,so that the amount of oxygen lost from here equals the amountof oxygen combined with the mercury on one side.Then he makes the reaction go in the other direction.First, he shows that this does not support combustion.Then he makes the reaction go in the opposite direction,forces the oxygen out of the retort, back into the cylinder,and shows that it now, once again, supports combustion.So, what he had done here was actually to discover oxygen.And he's shown that combustion and this process of calcinationis actually a process of addition, rather than a process of subtraction.It involves a combination of the substance with the oxygen.Not a combination of, not a loss of something from the mercury.You see the difference here?Priestly and the phlogistonists were saying that the processof combustion is, represents a loss; that the metal losesphlogiston into the air, and therefore, should lose weight.

Lavoisier goes on to show that the process actually works the other way,That it's actually a gain of something and the processof calcination, the burning of the metal, actually gains weight.Notice how he did this in a closed container, unlike our attempthere where the vapors and the gases and everything escaped.So, Lavoisier actually discovered oxygen in the sense that he wasthe one who recognized it as a substance that exists as partof the air, as opposed to Priestly who thought thatoxygen was simply air minus something.At last Lavoisier had come up with a way to go back to Boyle'sdefinition of an element to decide whether something was unmingled or mixt.Remember Boyle's definition was the definition of chemical purity.That is, that something that was an element was that whichother bodies could be broken down into, which could not be brokendown into something further and that which allsubstances or bodies were made of.Lavoisier had figured out a way to do this.It's very simple.If a reaction produces a product that weighs more than thereactant, then the product cannot be an element.Just think about this for a minute.If you take a piece of iron and you burn it or make a chemicalreaction with it, and the product that's produced by this weighsmore than the iron, it simply means that something has beenadded to the iron to make the new product, so the iron must be more basic.It must be more elemental.On the other hand, if you do a reaction where you takesomething like the calx of the mercury and it loses weight,then that means that the mercury is more elemental than the calx.Right.

So, in a chemical reaction, whichever thing weighs theleast, assuming that you're capturing all the products,is more likely to be an element.It doesn't prove that it's an element, but what it does is togive you a better idea of which things are likely to be elements.And, of course, you still can't decide whether or not the ironis an element or whether it's still a combination of things.But by a whole series of tests by which you can then reducethings further and further and further.Each time getting something of less and less weight,then you'll eventually reach things which no chemical processesare able to reduce further and that then becomes the workingdefinition of a substance which is an element until such somethingelse happens to reduce it even further.Which is exactly what we'll see happened with waterand other so called elemental substances.So as result of his quantitative studies, having brought the ideaof quantitative relationships into chemistry, Lavoisier publishedthe first textbook of chemistry, which in English is basicallythe elemental principles of chemistry.This book compares to the science of chemistry much the wayNewton's "Principia" did to the science of Physics.It made a clearly defined list of elements for onething, based upon Boyle's criteria.

Remember the criteria of mixt versus unmixt, or unmingled versus mixt.It also did such things, for example, as listing caloric as a chemical element.Remember caloric?It listed light as a chemical element, and it listed variousforms of acid as chemical elements.So, it did make many errors.But it still put forth and advanced the concept of chemistry,and I might say, that it took the mystery out of chemistry,although some people would say that there's nothing you can doto take the mystery out of chemistry.But certainly it transformed the science of chemistryfrom the spiritual side into a real science.So the result of Lavoisier's quantitative studies ledto a chemical revolution very similar to whathappened with physics after Newton.That is, that now a whole bunch of people hada basis for working with chemicals.They had an underlying theory which is conservation of mass.They had a way to determine whether or not something was an element.Or I should say, at least they had a way to determinethat something was not an element.So, with this, things advanced very rapidly.There were a couple of other changes that happened veryquickly around this time which will lead to John Dalton'satomic theory which we'll cover in the next program.One of these was the invention of the battery.I already mentioned this in terms of the concept of joule and heating.But the one thing that the battery did was to allowa continuous supply of electricity.

One of the first things that happened, once the battery wasinvented, was that the first thing people did with this was sticktwo electrodes of the battery into water.And when you do this you find bubbles of gas appearing on the two electrodes.It turns out that one of these gases is Laviosier's oxygen.The other one is hydrogen which Cavendish, the same Cavendishwho weighed the earth, had discovered a few years earlierand thought it was something else.But now we see that water, itself, which was thoughtby everybody, from Aristotle all the way to the alchemist,even by Lavoisier, himself, to be an element, is now found to besomething which can be decomposed,not by chemical means, but by electrical means.So now, all of a sudden, within a very short period of time wenot only have Lavoisier weighing things, but we have electricityshowing up as an element of chemistry.So, on one hand, electricity is related to physics and heat,and on the other hand, electricity is related to chemistry.It's clear that electricity plays a significant role in here.So, very quickly a whole lot of new elements were discovered.And in the next program we'll get into some of those elementsand the laws of chemistry and atomic theory and a lot of other exciting things.But, that's it for this program.So, remember, when it comes to science, get physical.Music