H
|
C
/ \\
H-C C-H
|| |
H-C C-H
\ //
C
|
H
Professor Kekulé saw at once that the demons of his subconscious self had furnished him with a clue to the labyrinth, and so it proved. We need not suppose that the benzene molecule if we could see it would look anything like this diagram of it, but the theory works and that is all the scientist asks of any theory. By its use thousands of new compounds have been constructed which have proved of inestimable value to man. The modern chemist is not a discoverer, he is an inventor. He sits down at his desk and draws a "Kekulé ring" or rather hexagon. Then he rubs out an H and hooks a nitro group (NO2) on to the carbon in place of it; next he rubs out the O2 of the nitro group and puts in H2; then he hitches on such other elements, or carbon chains and rings as he likes. He works like an architect designing a house and when he gets a picture of the proposed compounds to suit him he goes into the laboratory to make it. First he takes down the bottle of benzene and boils up some of this with nitric acid and sulfuric acid. This he puts in the nitro group and makes nitro-benzene, C6H5NO2. He treats this with hydrogen, which displaces the oxygen and gives C6H5NH2 or aniline, which is the basis of so many of these compounds that they are all commonly called "the aniline dyes." But aniline itself is not a dye. It is a colorless or brownish oil.
It is not necessary to follow our chemist any farther now that we have seen how he works, but before we pass on we will just look at one of his products, not one of the most complicated but still complicated enough.
A molecule of a coal-tar dye
The name of this is sodium ditolyl-disazo-beta-naphthylamine-6-sulfonic-beta-naphthylamine-3.6-disulfonate.
These chemical names of organic compounds are discouraging to the beginner and amusing to the layman, but that is because neither of them realizes that they are not really words but formulas. They are hyphenated because they come from Germany. The name given above is no more of a mouthful than "a-square-plus-two-a-b-plus-b-square" or "Third Assistant Secretary of War to the President of the United States of America." The trade name of this dye is Brilliant Congo, but while that is handier to say it does not mean anything. Nobody but an expert in dyes would know what it was, while from the formula name any chemist familiar with such compounds could draw its picture, tell how it would behave and what it was made from, or even make it. The old alchemist was a secretive and pretentious person and used to invent queer names for the purpose of mystifying and awing the ignorant. But the chemist in dropping the al- has dropped the idea of secrecy and his names, though equally appalling to the layman, are designed to reveal and not to conceal.
From this brief explanation the reader who has not studied chemistry will, I think, be able to get some idea of how these very intricate compounds are built up step by step. A completed house is hard to understand, but when we see the mason laying one brick on top of another it does not seem so difficult, although if we tried to do it we should not find it so easy as we think. Anyhow, let me give you a hint. If you want to make a good impression on a chemist don't tell him that he seems to you a sort of magician, master of a black art, and all that nonsense. The chemist has been trying for three hundred years to live down the reputation of being inspired of the devil and it makes him mad to have his past thrown up at him in this fashion. If his tactless admirers would stop saying "it is all a mystery and a miracle to me, and I cannot understand it" and pay attention to what he is telling them they would understand it and would find that it is no more of a mystery or a miracle than anything else. You can make an electrician mad in the same way by interrupting his explanation of a dynamo by asking: "But you cannot tell me what electricity really is." The electrician does not care a rap what electricity "really is"—if there really is any meaning to that phrase. All he wants to know is what he can do with it.
COMPARISON OF COAL AND ITS DISTILLATION PRODUCTS