Chemistry

"When one body combines with another in more than one proportion, the second proportion appears to be some multiple or divisor of the first; and this circumstance, observed and ingeniously illustrated by Mr. Dalton, led him to adopt the atomic hypothesis of chemical changes, which had been ably defended by Mr. Higgins in 1789, namely, that the chemical elements consist of certain indestructible particles which unite one and one, or one and two, or in some definite [] numbers."

"It was felt by many philosophers, particularly by the illustrious Bergman, that an improvement in chemical nomenclature was necessary, and in 1787, Messrs. Lavoisier, Morveau, Berthollet, and Fourcroy, presented to the world a plan for an almost entire change in the denomination of chemical substances, founded upon the idea of calling simple bodies by some names characteristic of their most striking qualities, and of naming compound bodies from the elements which composed them."

"It was a great achievement of the early chemists—with the crude experimental techniques available also with the ever-astonishing power of human reason... to discover this reduction of the world to its components, the chemical elements. Such reduction does not destroy its charm but adds understanding to sensation, and this understanding only deepens our delight."

"I have presented the as a kind of travel guide to an imaginary country, of which the elements are the various regions. This kingdom has a geography: the elements lie in particular juxtaposition to one another, and they are used to produce goods, much as a prairie produces wheat and a lake produces fish. It also has a history. Indeed, it has three kinds of history: the elements were discovered much as the lands of the world were discovered; the kingdom was mapped, just as the world was mapped, and the relative positions of the elements came to take on a great significance; and the elements have their own cosmic history, which can be traced back to the stars."

"I have raised a question which may be regarded as heretical. At the time when our modern conception of chemistry first dawned... the average chemist... accepted the elements as ultimate facts... absolutely simple, incapable of transmutation or decomposition, each a kind of barrier behind which we could not penetrate. ...[H]e said they were self-existent from all eternity ...But in our times... we cannot help asking what are the elements, whence do they come, what is their signification? ...These elements perplex us in our researches, baffle us in our speculations, and haunt us in our very dreams. They stretch like an unknown sea before us—mocking, mystifying and murmuring strange revelations and possibilities. If I venture to say that... elements are not simple and primordial... but have evolved from simpler matters—or... one sole kind of matter—I... give formal utterance to an idea... for some time "in the air" of science. Chemists, physicists, philosophers of the highest merit declare explicitly their belief that the seventy... elements of our text-books are not the which we must never hope to pass."

"1. Small particles called atoms exist and compose all matter; 2. They are indivisible and indestructible; 3. Atoms of the same chemical element have the same chemical properties and do not transmute or change into different elements."

"Some recent work by E. Fermi and L. Szilard, which has been communicated to me in manuscript, leads me to expect that the element may be turned into a new and important source of energy in the immediate future. Certain aspects of the situation seem to call for watchfulness and, if necessary, quick action on the part of the Administration..."

"Although the problem of transmuting chemical elements into each other is much older than a satisfactory definition of the very concept of chemical element, it is well known that the first and most important step towards its solution was made only nineteen years ago by the late Lord Rutherford, who started the method of the nuclear bombardments."

"No matter how properties of simple bodies may change in the free state, something remains constant, and when the element forms compounds, this something is material existence and establishes the characteristics of the compounds, which include the given element. In this respect we know only one constant peculiar to an element, namely the atomic weight. The size of the atomic weight, by the very essence of matter, is common to the simple body and all its compounds. Atomic weight belongs not to coal or diamond, but to carbon."

"1. The elements, if arranged according to their atomic weights, exhibit an evident periodicity of properties. 2. Elements which are similar as regards their chemical properties have atomic weights which are either of nearly the same value (e.g., platinum, iridium, osmium) or which increase regularly (e.g., potassium, rubidium, caesium). 3. The arrangement of the elements, or of groups of elements in the order of their atomic weights corresponds to their so-called valencies as well as, to some extent, to their distinctive chemical properties--as is apparent among other series in that of lithium, beryllium, barium, carbon, nitrogen, oxygen and iron [sic. The printed speech in J. Chem. Soc. says barium and iron. Obviously boron (B) and fluorine (F) are meant. Mendeleev's 1869 paper lists the symbols B and F rather than the names of the elements.--CJG] 4. The elements which are the most widely diffused have small atomic weights. 5. The magnitude of the atomic weight determines the character of the element just as the magnitude of the molecule determines the character of a compound body. 6. We must expect the discovery of many yet unknown elements, for example, elements analogous to aluminium and silicon, whose atomic weight would be between 65 and 75. 7. The atomic weight of an element may sometimes be amended by a knowledge of those of the contiguous elements. Thus, the atomic weight of tellurium must lie between 123 and 126, and cannot be 128. 8. Certain characteristic properties of the elements can be foretold from their atomic weights. ...[R]elations ...exist between the atomic weights of dissimilar elements ...hitherto ...neglected. I believe that the solution of some of the most important problems of our science lies in researches of this kind. To-day, 20 years after the above conclusions were formulated, they may still be considered as expressing the essence of the now well-known periodic law."

"These general considerations are sufficient to convince us, that in nature a substance exists whose properties are different from those of fire, air, water; and which is, like these other substances, one of the elements of compound bodies. But a vague assertion like this does not satisfy chemists. Besides the ascertaining of the exigence of the different substances submitted to their examination, they require to know the properties of these substances in their greatest degree of purity and simplicity; but they have found much difficulty and uncertainty in investigating the essential properties of the purest and simplest terrestrial element."

"These are the three ingredients in , which were known to the Chinese ...about 1,000 years ago: sulfur, and potassium nitrate. ...[T]hey're used in explosives and fireworks..."

"[T]here's burning, and... we lower it into sulfur dioxide. It carried on burning for a little while... [I]n sulfur dioxide, magnesium... breaks the bonds between the sulfur and the oxygen... itself becoming ... and releasing a little... sulfur... [T]hat's an example of sulfur dioxide as an ."

"This is a jar full of sulfur dioxide. ...[W]hen we pour solution, which is purple. ...It's lost its color. Let's try... [yellow] solution... Magic [as it turns ]? No, it's chemistry... [T]he sulfur dioxide is acting as a . It has caused them to change color on account of the change in of from +7 to +2, from +6 to +3."

"Sulfur dioxide... is... present in many wines. ...Usually ...sulfur dioxide is used as a food preservative, ...but they usually call it ...SO3^2-."

"This gas comes out of volcanoes as well as sulfur dioxide, and... is called . ...It has a phenomenally unpleasant smell of rotten eggs. Apart from that, it's unbelievably poisonous. ...[I]t undergoes an extraordinarily interesting reaction with sulfur dioxide. ...The lower jar is going yellow ...[W]e have made sulfur. ...also ...water. ...Two gases have reacted together to make a solid and a liquid. Secondly, two compounds of sulfur have made the element sulfur... Furthermore... it's... a redox reaction in which sulfur is reduced in one... and oxidized in the other. ...[M]any geologists believe that these two gases come out of volcanoes together and... make huge deposits of sulfur... found at the mouths of volcanoes."

"The way we test... for... is to put in a burning splint... and you see it has gone out."

"Sulfur is today obtained mainly from extraction from fossil fuels, from , from gas and from crude oil."

"[S]ulfur is unbelievably reactive. ...Sulfur can form 4 hooks, 2 hooks, -2. s +4, +6 and -2, 0 in... the element..."

"[A]bout 1,200 years ago... Al Razi... started making ... and... introduced marzipan into Europe... the tradition of using... sulfur for [marzipan] molds..."

"[the gas produced by burning sulfur]... has been used as a bleach and a fumigant since ancient Egyptian times."

"[A]n electric machine... first produced by ... is based on... attractor forces. ...[I]f you take a lump of sulfur and... rub it with a silk cloth... it will start to pick up bits of paper... hair... feather... [A]nother mineral... [Latin electrum]... had the same property. ...Otto von Guericke made a special globe out of sulfur ...and he described the remarkable reactions of things being ...attracted to it ...[I]t was the birth of ..."

"[T]he fact that sulfur has a low melting point of 115°C... has been exploited in making molds..."

"I'm going to melt the sulfur. ...The ...sulfur has molecules whose formulae are S8 ...They're pocket rings. They're like little crowns. ...[W]hen you get to roughly 160°C ...they break up ...and they start making a . They polymerize, like a plastic. ...I'm going to pour it into some cold water. ...like golden syrup. ...It's what we call plastic sulfur. ...[I]t's neither a liquid nor a solid."

"[T]he reason why is so interesting and why... the chemistry of sulfur is so interesting, is because sulfur is a very, very reactive element. Not only is it reactive, but it can form many different kinds of chemical combination..."

"is adding tiny amounts of sulfur to rubber to make it much stiffer. ...If not for ...vulcanization, we'd have no tires ...on motorcars, on airplanes or bicycles. We'd have no hoses in cars and so on... The world would be quite different. Vulcanization was invented by in 1840, one of the most important uses of sulfur today."

"[T]he sulfur-mercury theory... reasoning was... straightforward. They said... "If you mix this [mercury] with this [sulfur] in the right proportion, you can make any metal.""

"[T]he great Arabic alchemists... in the 8th or 9th century AD... came up with the idea that ultimately all metals are composed of sulfur and mercury..."

"Science is very difficult, and... the ancient world... was... a world of correspondences. ...[S]omething ...could well be ...actually made of things that make it look like something. ...That was the cleverest way ...people used to view the world in those days."

"This mineral ...is .... It's lead sulfide. ...Beautiful silver crystals. If you heat this strongly, this too will make sulfur come off."

"[P]yrites is the most widely distributed mineral of sulfur ...the chemical name is iron sulfide. ...It has the formula FeS2 and ...thousands of years ago people ...recognized that when you heat it, you ...make sulfur ..."

"There are many other sulfides, but this one is... special... Known in the ancient world as dragon's blood, and the reason... this red color. ...[W]hen they heated this strongly ...(This was particularly well known in ancient China and... in southern Spain.) ...it makes two... remarkable substances. One of them is sulfur... the other... is the liquid metal... mercury. ...[T]his fired up the imagination of ...ancient philosophers ...asking questions about ultimately what are all s made of."

"This sulfur-mercury theory... people continued to believe... for a thousand years."

"[S]ulfur beautifully burning in a gas jar full of oxygen... is a blue flame... [W]e now have a jar full of sulfurous fumes... [W]e allow the water to mix... The water has been colored green with a... ... As if by magic, the water... [turns] red and now it's gone yellow. ...[T]he ...gas ...when it reacts with water ...makes ."

"The word sulfur... goes... back to... the Hindu civilization... over 5,000 years ago. They had a word for sulfur... in... Sanskrit... sulvere... the enemy of copper. ...[T]hat is the ...destruction of the copper by the hot sulfur vapors... [T]he copper turns into... ...a black crumbly solid. ...The Latin [derived from sulvere] ...becomes sulphur."

"[I]t comes out of... volcanoes. ...[I]n ...human history things ...from underground have had... evil connotations... During the rise of various religions and... cultures sulfur was associated with evil... especially... in Christianity... connotations of hell, damnation... the dark underworld... punishment for... sins. ...[C]onnatations which we today ...know are not true..."

"[O]ne of the things that's associated with sulfur and... its compounds is unpleasant smells."

"It's burning with a blue flame... giving off the most foul and acrid fumes... So there is our "burning stone," which in old English was called brimstone."

"This is a volcano... that cloud of smoke... is... full of sulfurous fumes..."

"[W]hen you heat fool's gold... some crushed s... [y]ou can see the appearance of this yellow color, and ...a little bit of crackling... . ...[T]he crystals... are breaking up into a powder ...because when you heat things up, they expand on the outside, but not on the inside. ...The yellow stuff is beginning to collect ...It is sulfur ..."

"I have some beautiful crystals... these green ones and the blue ones... have been observed... [from] water evaporating on the side of lakes... close to volcanoes... [T]hey have... a glassy appearance. ...[T]he Sumerians, 2000 years ago ...described these ...The Latin word for glass is vitriolus [or vitrum] and so glassy substance became known as vitriols. ...[T]he medieval chemists discovered that if you heat these [crystals] very strongly... they give off a... terribly powerful smell and... a liquid which is capable of dissolving... metals. ...It was called oil of vitriol because it came from those glassy substances, but today we call it ."

"[C]hemical weapons were not new to the world. Besieged towns had thrown pots of burning sulfur, asphalt and pitch on soldiers since at least 200 CE."

"Pliny recorded processes involving metals, salts, sulfur, glass, mortar, soot, ash, and a large variety of s, earths, and stones."

"Reminiscent of Aristotle, Jabir proposed... two exhalations: "earthy smoke" (small particles of earth on their way to becoming fire) and "watery vapor" (small particles of water on their way to becoming air). These, he believed, mingled to become the metals. But Jabir modified the Aristotelian approach by proposing that exhalations underwent intermediate transformations into sulfur and mercury before becoming metal. The reason for the existence of different types of metals, he believed, was that the sulfur and mercury were not always pure. He proposed that if the right proportions of sulfur and mercury with the right purity could be found... gold would result."

"By 3000 BCE the Sumerians, perhaps while heating copper to make it more malleable, had discovered that more copper could be retrieved from the fire if the metal were heated with certain types of dirt and stones—that is, certain earths. These earths were the metal s, and the process they discovered, ', reduced metal salts to pure metal by the action of in the fire. The process of changing metal salts into pure metal is known as reduction because the metal without the accompanying oxygen, , or sulfur of the salt weighs less than the ore. Eventually metal workers learned to distinguish various metal-bearing ores by color, texture, weight, flame color, or smell when heated (such as garlic odor of ores) and they could produce a desired material on demand."

"He noticed that when copper and sulphur are mixed, they exhibit an , which increases with increasing temperature until finally they combine, and all traces of electricity disappear. Hence, he inferred that the same forces which, acting on masses at a distance, produce electric phenomena, when acting on atoms at small distances, produce chemical combination, the positive electricity of the one atom attracting and holding the negative of the other. In the positive charge is on one and the negative on the other, but these two charges have to be discharged through the electrode before the elements are set free. This is the reverse of what takes place in combination. Davy in this view differed from the electro-chemical theory of Berzelius."

"The did not arrive in China until around 1500 BCE, and iron appeared only about 500 BCE, but by the beginning of their alchemical age, around 100 CE, the Chinese had knowledge of and ... mercury, sulfur and several of the common salts, such as ."

"Paracelsus' greatest triumph was the use of mercury to treat , the new disease of the day. ...Paracelsus may have heard of the treatment in his travels... or the discovery may have been serendipitous, based on... the extension of the mercury-sulfur theory of the Islamic alchemists to a tria prima... of mercury (soul), sulfur (spirit), and salt (body). But... there is no record of the number of people he adversely affected while experimenting with potions that were not effective, which may have been considerable."

"Sulphuric acid he made by distilling green vitriol (ferrous sulphate), and by distilling nitre (potassium nitrate), and (double sulphate of potassium and aluminium). he prepared, but said it was of little use as a medicine."

"Paracelsus had discarded the disgusting decoctions of Galen and introduced chemical medicines, while Libavius and Sala had dismissed the fanatical conceptions which disfigured and almost nullified the teachings of both Paracelsians and Rosicrucians, but chemists still adhered either to the Aristotelian doctrine of the four elements, or to the later theory of the three principles (mercury, sulphur, and salt). (1577—1644) was the first to deny these propositions, and to begin a revolution in the philosophy of chemistry."