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Who said: “The path towards sustainable energy sources will be long and sometimes difficult. But America cannot resist this transition, we must lead it... That is how we will preserve our planet, commanded to our care by God. That’s what will lend meaning to the creed our fathers once declared.”
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Compound Quotes (54 quotes)

... every chemical combination is wholly and solely dependent on two opposing forces, positive and negative electricity, and every chemical compound must be composed of two parts combined by the agency of their electrochemical reaction, since there is no third force. Hence it follows that every compound body, whatever the number of its constituents, can be divided into two parts, one of which is positively and the other negatively electrical.
Essai sur la théorie des proportions chemiques (1819), 98. Quoted by Henry M. Leicester in article on Bessel in Charles Coulston Gillespie (editor), Dictionary of Scientific Biography (1981), Vol. 2, 94.
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Compounds formed by chemical attraction, possess new properties different from those of their component parts... chemists have long believed that the contrary took place in their combination. They thought, in fact, that the compounds possessed properties intermediate between those of their component parts; so that two bodies, very coloured, very sapid, or insapid, soluble or insoluble, fusible or infusible, fixed or volatile, assumed in chemical combination, a shade or colour, or taste, solubility or volatility, intermediate between, and in some sort composed of, the same properties which were considered in their principles. This is an illusion or error which modern chemistry is highly interested to overthrow.
Quoted in A General System of Chemical Knowledge (1804), Vol. I, trans. W. Nicholson, 102-3.
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Dass die bis jetzt unzerlegten chemischen Elemente absolut unzerlegbare Stoffe seien, ist gegenwärtig mindestens sehr unwahrscheinlich. Vielmehr scheint es, dass die Atome der Elemente nicht die letzten, sondern nur die näheren Bestandtheile der Molekeln sowohl der Elemente wie der Verbindungen bilden, die Molekeln oder Molecule als Massentheile erster, die Atome als solche zweiter Ordnung anzusehen sind, die ihrerseits wiederum aus Massentheilchen einer dritten höheren Ordnung bestehen werden.
That the as yet undivided chemical elements are absolutely irreducible substances, is currently at least very unlikely. Rather it seems, that the atoms of elements are not the final, but only the immediate constituents of the molecules of both the elements and the compounds—the Molekeln or molecule as foremost division of matter, the atoms being considered as second order, in turn consisting of matter particles of a third higher order.
[Speculating in 1870, on the existence of subatomic particles, in opening remark of the paper by which he became established as co-discoverer of the Periodic Law.]
'Die Natur der chemischen Elemente als Function ihrer Atomgewichte' ('The Nature of the Chemical Elements as a Function of their Atomic Weight'), Annalen der Chemie (1870), supp. b, 354. Original German paper reprinted in Lothar Meyer and Dmitry Ivanovich Mendeleyev, Das natürliche System der chemischen Elemente: Abhandlungen (1895), 9. Translation by Webmaster, with punctuation faithful to the original, except a comma was changed to a dash to improve readability.
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A chemical compound once formed would persist for ever, if no alteration took place in surrounding conditions. But to the student of Life the aspect of nature is reversed. Here, incessant, and, so far as we know, spontaneous change is the rule, rest the exception—the anomaly to be accounted for. Living things have no inertia and tend to no equilibrium.
From Address (22 Jul 1854) delivered at St. Martin’s Hall, published as a pamphlet (1854), 7, and collected in 'Educational Value of Natural History Sciences', Lay Sermons, Addresses, and Reviews (1870), 75.
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A chemical name should not be a phrase, it ought not to require circumlocutions to become definite; it should not be of the type “Glauber’s salt”, which conveys nothing about the composition of the substance; it should recall the constituents of a compound; it should be non-committal if nothing is known about the substance; the names should preferably be coined from Latin or Greek, so that their meaning can be more widely and easily understood; the form of the words should be such that they fit easily into the language into which they are to be incorporated.
(1782) As quoted in Archibald Clow, Chemical Revolution: A Contribution to Social Technology (1952, 1992), 618.
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A schism has taken place among the chemists. A particular set of them in France have undertaken to remodel all the terms of the science, and to give every substance a new name, the composition, and especially the termination of which, shall define the relation in which it stands to other substances of the same family, But the science seems too much in its infancy as yet, for this reformation; because in fact, the reformation of this year must be reformed again the next year, and so on, changing the names of substances as often as new experiments develop properties in them undiscovered before. The new nomenclature has, accordingly, been already proved to need numerous and important reformations. ... It is espoused by the minority here, and by the very few, indeed, of the foreign chemists. It is particularly rejected in England.
Letter to Dr. Willard (Paris, 1788). In Thomas Jefferson and John P. Foley (ed.), The Jeffersonian Cyclopedia (1900), 135. From H.A. Washington, The Writings of Thomas Jefferson (1853-54). Vol 3, 15.
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A very interesting set of compounds that were waiting for the right disease.
[Commenting on AZT and similar drugs he had synthesized.]
Quoted in 'Jerome Horwitz, AZT Creator, Dies at 93', New York Times (21 Sep 2012).
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About eight days ago I discovered that sulfur in burning, far from losing weight, on the contrary, gains it; it is the same with phosphorus; this increase of weight arises from a prodigious quantity of air that is fixed during combustion and combines with the vapors. This discovery, which I have established by experiments, that I regard as decisive, has led me to think that what is observed in the combustion of sulfur and phosphorus may well take place in the case of all substances that gain in weight by combustion and calcination; and I am persuaded that the increase in weight of metallic calxes is due to the same cause... This discovery seems to me one of the most interesting that has been made since Stahl and since it is difficult not to disclose something inadvertently in conversation with friends that could lead to the truth I have thought it necessary to make the present deposit to the Secretary of the Academy to await the time I make my experiments public.
Sealed note deposited with the Secretary of the French Academy 1 Nov 1772. Oeuvres de Lavoisier, Correspondance, Fasc. II. 1770-75 (1957), 389-90. Adapted from translation by A. N. Meldrum, The Eighteenth-Century Revolution in Science (1930), 3.
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All the experiments which have been hitherto carried out, and those that are still being daily performed, concur in proving that between different bodies, whether principles or compounds, there is an agreement, relation, affinity or attraction (if you will have it so), which disposes certain bodies to unite with one another, while with others they are unable to contract any union: it is this effect, whatever be its cause, which will help us to give a reason for all the phenomena furnished by chemistry, and to tie them together.
From Elemens de Chymie Theorique (1749). As quoted, in Trevor Harvey Levere, Affinity and Matter: Elements of Chemical Philosophy, 1800-1865 (1971), 17.
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An aromatic compound may be defined as a cyclic compound with a large resonance energy where all the annular atoms take part in a single conjugated system.
Electronic Theory of Organic Chemistry (1949), 160.
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An example of such emergent phenomena is the origin of life from non-living chemical compounds in the oldest, lifeless oceans of the earth. Here, aided by the radiation energy received from the sun, countless chemical materials were synthesized and accumulated in such a way that they constituted, as it were, a primeval “soup.” In this primeval soup, by infinite variations of lifeless growth and decay of substances during some billions of years, the way of life was ultimately reached, with its metabolism characterized by selective assimilation and dissimilation as end stations of a sluiced and canalized flow of free chemical energy.
In 'The Scientific Character of Geology', The Journal of Geology (Jul 1961), 69, No. 4, 458.
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At the planet’s very heart lies a solid rocky core, at least five times larger than Earth, seething with the appalling heat generated by the inexorable contraction of the stupendous mass of material pressing down to its centre. For more than four billion years Jupiter’s immense gravitational power has been squeezing the planet slowly, relentlessly, steadily, converting gravitational energy into heat, raising the temperature of that rocky core to thirty thousand degrees, spawning the heat flow that warms the planet from within. That hot, rocky core is the original protoplanet seed from the solar system’s primeval time, the nucleus around which those awesome layers of hydrogen and helium and ammonia, methane, sulphur compounds and water have wrapped themselves.
Ben Bova
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Briefly, in the act of composition, as an instrument there intervenes and is most potent, fire, flaming, fervid, hot; but in the very substance of the compound there intervenes, as an ingredient, as it is commonly called, as a material principle and as a constituent of the whole compound the material and principle of fire, not fire itself. This I was the first to call phlogiston.
Specimen Beccherianum (1703). Trans. J. R. Partington, A History of Chemistry (1961), Vol. 2, 668.
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Carbon is, as may easily be shown and as I shall explain in greater detail later, tetrabasic or tetratomic, that is 1 atom of carbon = C = 12 is equivalent to 4 At.H.
'On the so-called Copulated Compounds and the Theory of Polyatomic Radicals', Annalen (1857), 4, 133. Trans. in J. R. Partington, A History of Chemistry (1972), Vol. 4, 536.
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Chymia, or Alchemy and Spagyrism, is the art of resolving compound bodies into their principles and of combining these again.
Fundamenta Chymiae (1720). Trans. J. R. Partington, A History of Chemistry (1961), Vol. 2, 664.
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Compare ... the various quantities of the same element contained in the molecule of the free substance and in those of all its different compounds and you will not be able to escape the following law: The different quantities of the same element contained in different molecules are all whole multiples of one and the same quantity, which always being entire, has the right to be called an atom.
Sketch of a Course of Chemical Philosophy (1858), Alembic Club Reprint (1910), 11.
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Compounds of gaseous substances with each other are always formed in very simple ratios, so that representing one of the terms by unity, the other is 1, 2, or at most 3 ... The apparent contraction of volume suffered by gas on combination is also very simply related to the volume of one of them.
Mémoires de la Société d' Arcueil, 1809, 2, 233-4. Trans. Foundations of the Molecular Theory, Alembic Club Reprint, no. 4 (1950), 24.
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During my stay in London I resided for a considerable time in Clapham Road in the neighbourhood of Clapham Common... One fine summer evening I was returning by the last bus 'outside' as usual, through the deserted streets of the city, which are at other times so full of life. I fell into a reverie (Träumerei), and 10, the atoms were gambolling before my eyes! Whenever, hitherto, these diminutive beings had appeared to me, they had always been in motion: but up to that time I had never been able to discern the nature of their motion. Now, however, I saw how, frequently, two smaller atoms united to form a pair: how the larger one embraced the two smaller ones: how still larger ones kept hold of three or even four of the smaller: whilst the whole kept whirling in a giddy dance. I saw how the larger ones formed a chain, dragging the smaller ones after them but only at the ends of the chain. I saw what our past master, Kopp, my highly honoured teacher and friend has depicted with such charm in his Molekular-Welt: but I saw it long before him. The cry of the conductor 'Clapham Road', awakened me from my dreaming: but I spent part of the night in putting on paper at least sketches of these dream forms. This was the origin of the 'Structural Theory'.
Kekule at Benzolfest in Berichte (1890), 23, 1302.
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Dust consisting of fine fibers of asbestos, which are insoluble and virtually indestructible, may become a public health problem in the near future. At a recent international conference on the biological effects of asbestos sponsored by the New York Academy of Sciences, participants pointed out on the one hand that workers exposed to asbestos dust are prone in later life to develop lung cancer, and on the other hand that the use of this family of fibrous silicate compounds has expanded enormously during the past few decades. A laboratory curiosity 100 years ago, asbestos today is a major component of building materials.
In Scientific American (Sep 1964). As cited in '50, 100 & 150 Years Ago', Scientific American (Dec 2014), 311, No. 6, 98.
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Food is at present obtained almost entirely from the energy of the sunlight. The radiation from the sun produces from the carbonic acid in the air more or less complicated carbon compounds which serve us in plants and vegetables. We use the latent chemical energy of these to keep our bodies warm, we convert it into muscular effort. We employ it in the complicated process of digestion to repair and replace the wasted cells of our bodies. … If the gigantic sources of power become available, food would be produced without recourse to sunlight. Vast cellars, in which artificial radiation is generated, may replace the cornfields and potato patches of the world.
From 'Fifty Years Hence', Strand Magazine (Dec 1931). Reprinted in Popular Mechanics (Mar 1932), 57, No. 3, 396-397.
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Free men are aware of the imperfection inherent in human affairs, and they are willing to fight and die for that which is not perfect. They know that basic human problems can have no final solutions, that our freedom, justice, equality, etc. are far from absolute, and that the good life is compounded of half measures, compromises, lesser evils, and gropings toward the perfect. The rejection of approximations and the insistence on absolutes are the manifestation of a nihilism that loathes freedom, tolerance, and equity.
In The Temper of Our Time (1967), 103.
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From what has been said it is also evident, that the Whiteness of the Sun's Light is compounded all the Colours wherewith the several sorts of Rays whereof that Light consists, when by their several Refrangibilities they are separated from one another, do tinge Paper or any other white Body whereon they fall. For those Colours ... are unchangeable, and whenever all those Rays with those their Colours are mix'd again, they reproduce the same white Light as before.
Opticks (1704), Book 1, Part 2, Exper. XV, 114.
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Gentlemen and ladies, this is ordinary alcohol, sometimes called ethanol; it is found in all fermented beverages. As you well know, it is considered by many to be poisonous, a belief in which I do not concur. If we subtract from it one CH2-group we arrive at this colorless liquid, which you see in this bottle. It is sometimes called methanol or wood alcohol. It is certainly more toxic than the ethanol we have just seen. Its formula is CH3OH. If, from this, we subtract the CH2-group, we arrive at a third colorless liquid, the final member of this homologous series. This compound is hydrogen hydroxide, best known as water. It is the most poisonous of all.
In Ralph Oesper, The Human Side of Scientists (1975), 189.
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I have considered the two terms you want to substitute for eisode and exode, and upon the whole I am disposed to recommend instead of them anode and cathode. These words may signify eastern and western way, just as well as the longer compounds which you mention … I may mention too that anodos and cathodos are good, genuine Greek words, and not compounds coined for the purpose.
Letter to Michael Faraday (25 Apr 1834). Quoted in I. Todhunter (ed.), William Whewell: An Account of His Writings with Selections From His Literary and Scientific Correspondence (1876), Vol. 2, 179.
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I should like to call the number of atom groups, with which an elementary atom coordinates … to form a complex radical, the coordination number of the atom in question … We must differentiate between valence number and coordination number. The valence number indicates the maximum number of monovalent atoms which can be bound directly to the atom in question without the participation of other elementary atoms … Perhaps this concept [of coordination number] is destined to serve as a basis for the theory of the constitution of inorganic compounds, just as valence theory formed the basis for the constitutional theory of carbon compounds.
In 'Beitrag zur Konstitution anorganischer Verbindungen', Zeitschrift fur anorganische Chemie, (1893), 3, 267-330. Translated in George G. Kauffman (ed.), Classics in Coordination Chemistry: Part I: The Selected Papers of Alfred Werner (1968), 84-87.
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I think chemistry is being frittered away by the hairsplitting of the organic chemists; we have new compounds discovered, which scarcely differ from the known ones and when discovered are valueless—very illustrations perhaps of their refinements in analysis, but very little aiding the progress of true science.
Letter to William Grove (5 Jan 1845), The Letters of Faraday and Schoenbein, 1836-1862 (1899), Footnote, 209.
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I trust ... I have succeeded in convincing you that modern chemistry is not, as it has so long appeared, an ever-growing accumulation of isolated facts, as impossible for a single intellect to co-ordinate as for a single memory to grasp.
The intricate formulae that hang upon these walls, and the boundless variety of phenomena they illustrate, are beginning to be for us as a labyrinth once impassable, but to which we have at length discovered the clue. A sense of mastery and power succeeds in our minds to the sort of weary despair with which we at first contemplated their formidable array. For now, by the aid of a few general principles, we find ourselves able to unravel the complexities of these formulae, to marshal the compounds which they represent in orderly series; nay, even to multiply their numbers at our will, and in a great measure to forecast their nature ere we have called them into existence. It is the great movement of modern chemistry that we have thus, for an hour, seen passing before us. It is a movement as of light spreading itself over a waste of obscurity, as of law diffusing order throughout a wilderness of confusion, and there is surely in its contemplation something of the pleasure which attends the spectacle of a beautiful daybreak, something of the grandeur belonging to the conception of a world created out of chaos.
Concluding remark for paper presented at the Friday Discourse of the the Royal Institution (7 Apr 1865). 'On the Combining Power of Atoms', Proceedings of the Royal Institution (1865), 4, No. 42, 416.
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In deriving a body from the water type I intend to express that to this body, considered as an oxide, there corresponds a chloride, a bromide, a sulphide, a nitride, etc., susceptible of double compositions, or resulting from double decompositions, analogous to those presented by hydrochloric acid, hydrobromic acid, sulphuretted hydrogen, ammonia etc., or which give rise to the same compounds. The type is thus the unit of comparison for all the bodies which, like it, are susceptible of similar changes or result from similar changes.
Traité de Chimie Organique, 1856, 4, 587. Trans. J. R. Partington, A History of Chemistry, (1970), Vol. 4, 456.
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In every combustion there is disengagement of the matter of fire or of light. A body can burn only in pure air [oxygen]. There is no destruction or decomposition of pure air and the increase in weight of the body burnt is exactly equal to the weight of air destroyed or decomposed. The body burnt changes into an acid by addition of the substance that increases its weight. Pure air is a compound of the matter of fire or of light with a base. In combustion the burning body removes the base, which it attracts more strongly than does the matter of heat, which appears as flame, heat and light.
'Memoire sur la combustion en général', Mémoires de l'Académie des Sciences, 1777, 592. Reprinted in Oeuvres de Lavoisier (1864), Vol. 2, 225-33, trans. M. P. Crosland.
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In inorganic chemistry the radicals are simple; in organic chemistry they are compounds—that is the sole difference.
Joint paper with Liebig, but written by Dumas, Comptes Rendus 1837, 5, 567. Trans. J. R. Partington, A History of Chemistry, Vol. 4, 351.
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Incandescent carbon particles, by the tens of millions, leap free of the log and wave like banners, as flame. Several hundred significantly different chemical reactions are now going on. For example, a carbon atom and four hydrogen atoms, coming out of the breaking cellulose, may lock together and form methane, natural gas. The methane, burning (combining with oxygen), turns into carbon dioxide and water, which also go up the flue. If two carbon atoms happen to come out of the wood with six hydrogen atoms, they are, agglomerately, ethane, which bums to become, also, carbon dioxide and water. Three carbons and eight hydrogens form propane, and propane is there, too, in the fire. Four carbons and ten hydrogens—butane. Five carbons … pentane. Six … hexane. Seven … heptane. Eight carbons and eighteen hydrogens—octane. All these compounds come away in the breaking of the cellulose molecule, and burn, and go up the chimney as carbon dioxide and water. Pentane, hexane, heptane, and octane have a collective name. Logs burning in a fireplace are making and burning gasoline.
In 'Firewood', Pieces of the Frame (1975), 205-206.
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It cannot, of course, be stated with absolute certainty that no elements can combine with argon; but it appears at least improbable that any compounds will be formed.
[This held true for a century, until in Aug 2000, the first argon compound was formed, argon fluorohydride, HArF, but stable only below 40 K (−233 °C).]
Gases of the Atmosphere (1896), 193. Referenced in William H. Brock, The Chemical Tree: A History of Chemistry (2000), 339 and 671.
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It is often said that all the conditions for the first production of a living being are now present, which could ever have been present. But if (and oh what a big if) we could conceive in some warm little pond with all sort of ammonia and phosphoric salts—light, heat, electricity present, that a protein compound was chemically formed, ready to undergo still more complex changes, at the present such matter would be instantly devoured, or absorbed, which would not have been the case before living creatures were formed.
Letter (1 Feb 1871) to Joseph Dalton Hooker. In The Life and Letters of Charles Darwin (1888), Vol. 3, 18.
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It [the Euglena] is a perfect laboratory in itself, and it will act and react upon the water and the matters contained therein; converting them into new compounds resembling its own substance, and at the same time giving up portions of its own substance which have become effete.
From Address (22 Jul 1854) delivered at St. Martin’s Hall, published as a pamphlet (1854), 8, and collected in 'Educational Value of Natural History Sciences', Lay Sermons, Addresses, and Reviews (1870), 75.
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Medicine is not only a science; it is also an art. It does not consist of compounding pills and plasters; it deals with the very processes of life, which must be understood before they may be guided.
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One of the most immediate consequences of the electrochemical theory is the necessity of regarding all chemical compounds as binary substances. It is necessary to discover in each of them the positive and negative constituents... No view was ever more fitted to retard the progress of organic chemistry. Where the theory of substitution and the theory of types assume similar molecules, in which some of the elements can be replaced by others without the edifice becoming modified either in form or outward behaviour, the electrochemical theory divides these same molecules, simply and solely, it may be said, in order to find in them two opposite groups, which it then supposes to be combined with each other in virtue of their mutual electrical activity... I have tried to show that in organic chemistry there exist types which are capable, without destruction, of undergoing the most singular transformations according to the nature of the elements.
Traité de Chemie Appliquée aux Arts, Vol. I (1828), 53. Trans. J. R. Partington, A History of Chemistry, Vol. 4, 366.
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Organic chemistry is the chemistry of carbon compounds. Biochemistry is the study of carbon compounds that crawl.
Often seen quoted, though without source, for example, in Vassilis Mougios, Exercise Biochemistry (2006), 1. [Please contact webmaster if you can identify the author and a primary source.]
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Recently, we’ve reported that we have made all five bases, the compounds that spell out the instructions for all life and are a part of the nucleic acids, RNA and DNA. Not only did we make all five bases but we found them in a meteorite! So that these two things coming together really assure us that the molecules necessary for life can be found in the absence of life. This was the biggest stumbling block.
In Space World (1985), 5, 25.
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The chemical compounds are comparable to a system of planets in that the atoms are held together by chemical affinity. They may be more or less numerous, simple or complex in composition, and in the constitution of the materials, they play the same role as Mars and Venus do in our planetary system, or the compound members such as our earth with its moon, or Jupiter with its satellites... If in such a system a particle is replaced by one of different character, the equilibrium can persist, and then the new compound will exhibit properties similar to those shown by the original substance.
Quoted in Ralph Oesper, The Human Side of Scientists (1975), 55.
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The discovery that these soccer-ball-like molecules can be made in large quantities will have an effect on chemistry like the sowing of a bucket of flower seeds—the results will spring up everywhere from now on. I’d be surprised if we don’t see thousands of new fullerene compounds in the next few years, some of which are almost certain to have important uses.
As quoted in Malcolm W. Browne, 'Bizarre New Class of Molecules Spawns Its Own Branch of Chemistry', New York Times (25 Dec 1990), Late Edition (East Coast), L37.
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The most fundamental difference between compounds of low molecular weight and macromolecular compounds resides in the fact that the latter may exhibit properties that cannot be deduced from a close examination of the low molecular weight materials. Not very different structures can be obtained from a few building blocks; but if 10,000 or 100,000 blocks are at hand, the most varied structures become possible, such as houses or halls, whose special structure cannot be predicted from the constructions that are possible with only a few building blocks... Thus, a chromosome can be viewed as a material whose macromolecules possess a well defined arrangement, like a living room in which each piece of furniture has its place and not, as in a warehouse, where the pieces of furniture are placed together in a heap without design.
Quoted, without citation, in Ralph E. Oesper (ed.), The Human Side of Scientists (1975), 175.
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The only difference between elements and compounds consists in the supposed impossibility of proving the so-called elements to be compounds.
'Faraday Lecture: Elements and Compounds', Journal of the Chemical Society (1904), 85, 520.
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The progress of synthesis, or the building up of natural materials from their constituent elements, proceeds apace. Even some of the simpler albuminoids, a class of substances of great importance in the life process, have recently been artificially prepared. ... Innumerable entirely new compounds have been produced in the last century. The artificial dye-stuffs, prepared from materials occurring in coal-tar, make the natural colours blush. Saccharin, which is hundreds of times sweeter than sugar, is a purely artificial substance. New explosives, drugs, alloys, photographic substances, essences, scents, solvents, and detergents are being poured out in a continuous stream.
In Matter and Energy (1912), 45-46.
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There is an occasional glimmer of fertility [as compounds], the chemical equivalent of a blade of grass [in a desert]. So, gone … is the justification for “inert.” [Group 0 elements] are now known collectively as the noble gases, a name intended to imply a kind of chemical aloofness rather than a rigorous chastity.
In The Periodic Kingdom: A Journey Into the Land of the Chemical Elements (1995), 9.
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There is no sharp boundary line separating the reactions of the immune bodies from chemical processes between crystalloids, just as in nature there exists every stage between crystalloid and colloid. The nearer the colloid particle approximates to the normal electrolyte, the nearer its compounds must obviously come to conforming to the law of simple stoichiometric proportions, and the compounds themselves to simple chemical compounds. At this point, it should be recalled that Arrhenius has shown that the quantitative relationship between toxin and antitoxin is very similar to that between acid and base.
Landsteiner and Nicholas von Jagic, 'Uber Reaktionen anorganischer Kolloide und Immunkorper', Münchener medizinischer Wochenschrift (1904), 51, 1185-1189. Trans. Pauline M. H. Mazumdar.
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Those of us who were familiar with the state of inorganic chemistry in universities twenty to thirty years ago will recall that at that time it was widely regarded as a dull and uninteresting part of the undergraduate course. Usually, it was taught almost entirely in the early years of the course and then chiefly as a collection of largely unconnected facts. On the whole, students concluded that, apart from some relationships dependent upon the Periodic table, there was no system in inorganic chemistry comparable with that to be found in organic chemistry, and none of the rigour and logic which characterised physical chemistry. It was widely believed that the opportunities for research in inorganic chemistry were few, and that in any case the problems were dull and uninspiring; as a result, relatively few people specialized in the subject... So long as inorganic chemistry is regarded as, in years gone by, as consisting simply of the preparations and analysis of elements and compounds, its lack of appeal is only to be expected. The stage is now past and for the purpose of our discussion we shall define inorganic chemistry today as the integrated study of the formation, composition, structure and reactions of the chemical elements and compounds, excepting most of those of carbon.
Inaugural Lecture delivered at University College, London (1 Mar 1956). In The Renaissance of Inorganic Chemistry (1956), 4-5.
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We define organic chemistry as the chemistry of carbon compounds.
Lehrbuch der Organischen Chemie (1861), Vol. 1, 11. Trans. W. H. Brock.
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We may regard [Scheele] not only as having given the first indication of the rich harvest to be reaped by the investigation of the compounds of organic chemistry, but as having been the first to discover and make use of characteristic reactions by which closely allied substances can be detected and separated, so that he must be considered one of the chief founders of analytical chemistry.
In Treatise on Chemistry (1877, 1890), Vol. 1, 23.
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When carbon (C), Oxygen (o) and hydrogen (H) atoms bond in a certain way to form sugar, the resulting compound has a sweet taste. The sweetness resides neither in the C, nor in the O, nor in the H; it resides in the pattern that emerges from their interaction. It is an emergent property. Moreover, strictly speaking, is not a property of the chemical bonds. It is a sensory experience that arises when the sugar molecules interact with the chemistry of our taste buds, which in turns causes a set of neurons to fire in a certain way. The experience of sweetness emerges from that neural activity.
In The Hidden Connections (2002), 116-117.
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When the formulae of inorganic chemical compounds are considered, even a superficial observer is struck with the general symmetry of their construction; the compounds of nitrogen, phosphorus, antimony and arsenic especially exhibit the tendency of the elements to form compounds containing 3 or 5 equivs. of other elements, and it is in these proportions that their affinities are best satisfied; thus in the ternal group we have NO3, NH3, NI3, NS3, PO3, PH3, PCl3, SbO3, SbH3, SbCl3, AsO3, AsH3, AsCl3 &c; and in the five-atom group NO4, NH4O, NH4I, PO5, PH4I, &c. Without offering any hypothesis regarding the cause of this symmetrical grouping of atoms, it is sufficiently evident, from the examples just given, that such a tendency or law prevails, and that, no matter what the character of the uniting atoms may be, the combining power of the attracting element, if I may be allowed the term, is always satisfied by the same number of these atoms.
'On a New Series of Organic Bodies Containing Metals', Philosophical Transactions of the Royal Society of London, 1852, 14:2, 440.

When the simplest compounds of this element are considered (marsh gas, chloride of carbon, chloroform, carbonic acid, phosgene, sulphide of carbon, hydrocyanic acid, etc.) it is seen that the quantity of carbon which chemists have recognised as the smallest possible, that is, as an atom, always unites with 4 atoms of a monatomic or with two atoms of a diatomic element; that in general, the sum of the chemical units of the elements united with one atom of carbon is 4. This leads us to the view that carbon is tetratomic or tetrabasic. In the cases of substances which contain several atoms of carbon, it must be assumed that at least some of the atoms are in some way held in the compound by the affinity of carbon, and that the carbon atoms attach themselves to one another, whereby a part of the affinity of the one is naturally engaged with an equal part of the affinity of the other. The simplest and therefore the most probable case of such an association of carbon atoms is that in which one affinity unit of one is bound by one of the other. Of the 2 x 4 affinity units of the two carbon atoms, two are used up in holding the atoms together, and six remain over, which can be bound by atom)' of other elements.
'Ueber die Konstitution und die Metamorphosen der chemischen Verbindungen', Annalen (1858) 5, 106. Trans. in J. R. Partington, A History of Chemistry (1972), Vol. 4, 536.
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When ultra-violet light acts on a mixture of water, carbon dioxide, and ammonia, a vast variety of organic substances are made, including sugars and apparently some of the materials from which proteins are built up…. But before the origin of life they must have accumulated till the primitive oceans reached the consistency of hot dilute soup…. The first living or half-living things were probably large molecules synthesized under the influence of the sun’s radiation, and only capable of reproduction in the particularly favorable medium in which they originated….
In 'The Origin of Life', The Inequality of Man: And Other Essays (1932, 1937), 152.
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Without preparing fluorine, without being able to separate it from the substances with which it is united, chemistry has been able to study and to analyze a great number of its compounds. The body was not isolated, and yet its place was marked in our classifications. This well demonstrates the usefulness of a scientific theory, a theory which is regarded as true during a certain time, which correlates facts and leads the mind to new hypotheses, the first causes of experimentation; which, little by little, destroy the theory itself, in order to replace it by another more in harmony with the progress of science.
[Describing the known history of fluorine compounds before his isolation of the element.]
'Fluorine', lecture at the Royal Institution (28 May 1897), translated from the French, in Proceedings of the Royal Institution (1897). In Annual Report of the Board of Regents of the Smithsonian Institution to July 1897 (1898), 262.
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[The] structural theory is of extreme simplicity. It assumes that the molecule is held together by links between one atom and the next: that every kind of atom can form a definite small number of such links: that these can be single, double or triple: that the groups may take up any position possible by rotation round the line of a single but not round that of a double link: finally that with all the elements of the first short period [of the periodic table], and with many others as well, the angles between the valencies are approximately those formed by joining the centre of a regular tetrahedron to its angular points. No assumption whatever is made as to the mechanism of the linkage. Through the whole development of organic chemistry this theory has always proved capable of providing a different structure for every different compound that can be isolated. Among the hundreds of thousands of known substances, there are never more isomeric forms than the theory permits.
Presidential Address to the Chemical Society (16 Apr 1936), Journal of the Chemical Society (1936), 533.
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Carl Sagan Thumbnail In science it often happens that scientists say, 'You know that's a really good argument; my position is mistaken,' and then they would actually change their minds and you never hear that old view from them again. They really do it. It doesn't happen as often as it should, because scientists are human and change is sometimes painful. But it happens every day. I cannot recall the last time something like that happened in politics or religion. (1987) -- Carl Sagan
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