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 “Kekule ring” or rather hexagon.  Then he rubs out an H and hooks a nitro group (NO_{2}) on to the carbon in place of it; next he rubs out the O_{2} of the nitro group and puts in H_{2}; 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, C_{6}H_{5}NO_{2}.  He treats this with hydrogen, which displaces the oxygen and gives C_{6}H_{5}NH_{2} 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.

[Illustration:  A molecule of a coal-tar dye]

The name of this is sodium ditolyl-disazo-beta-naphthylam
ine-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.