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.

[Illustration:  COMPARISON OF COAL AND ITS DISTILLATION PRODUCTS From Hesse’s “The Industry of the Coal Tar Dyes,” Journal of Industrial and Engineering Chemistry, December, 1914]

The tar obtained from the gas plant or the coke plant has now to be redistilled, giving off the ten “crudes” already mentioned and leaving in the still sixty-five per cent. of pitch, which may be used for roofing, paving and the like.  The ten primary products or crudes are then converted into secondary products or “intermediates” by processes like that for the conversion of benzene into aniline.  There are some three hundred of these intermediates in use and from them are built up more than three times as many dyes.  The year before the war the American custom house listed 5674 distinct brands of synthetic dyes imported, chiefly from Germany, but some of these were trade names for the same product made by different firms or represented by different degrees of purity or form of preparation.  Although the number of possible products is unlimited and over five thousand dyes are known, yet only about nine hundred are in use.  We can summarize the situation so: 

  Coal-tar —­> 10 crudes —­> 300 intermediates —­> 900 dyes —­> 5000 brands.

Or, to borrow the neat simile used by Dr. Bernhard C. Hesse, it is like cloth-making where “ten fibers make 300 yarns which are woven into 900 patterns.”

The advantage of the artificial dyestuffs over those found in nature lies in their variety and adaptability.  Practically any desired tint or shade can be made for any particular fabric.  If my lady wants a new kind of green for her stockings or her hair she can have it.  Candies and jellies and drinks can be made more attractive and therefore more appetizing by varied colors.  Easter eggs and Easter bonnets take on new and brighter hues.