It required 12,000 of the mollusks to supply the little material needed for analysis, but once the chemist had identified it he did not need to bother the Murex further, for he could make it by the ton if he had wanted to.  The coloring principle turned out to be a di-brom indigo, that is the same as the substance extracted from the Indian plant, but with the addition of two atoms of bromine.  Why a particular kind of a shellfish should have got the habit of extracting this rare element from sea water and stowing it away in this peculiar form is “one of those things no fellow can find out.”  But according to the chemist the Murex mollusk made a mistake in hitching the bromine to the wrong carbon atoms.  He finds as he would word it that the 6:6’ di-brom indigo secreted by the shellfish is not so good as the 5:5’ di-brom indigo now manufactured at a cheap rate and in unlimited quantity.  But we must not expect too much of a mollusk’s mind.  In their cheapness lies the offense of the aniline dyes in the minds of some people.  Our modern aristocrats would delight to be entitled “porphyrogeniti” and to wear exclusive gowns of “purple and scarlet from the isles of Elishah” as was done in Ezekiel’s time, but when any shopgirl or sailor can wear the royal color it spoils its beauty in their eyes.  Applied science accomplishes a real democracy such as legislation has ever failed to establish.

Any kind of dye found in nature can be made in the laboratory whenever its composition is understood and usually it can be made cheaper and purer than it can be extracted from the plant.  But to work out a profitable process for making it synthetically is sometimes a task requiring high skill, persistent labor and heavy expenditure.  One of the latest and most striking of these achievements of synthetic chemistry is the manufacture of indigo.

Indigo is one of the oldest and fastest of the dyestuffs.  To see that it is both ancient and lasting look at the unfaded blue cloths that enwrap an Egyptian mummy.  When Caesar conquered our British ancestors he found them tattooed with woad, the native indigo.  But the chief source of indigo was, as its name implies, India.  In 1897 nearly a million acres in India were growing the indigo plant and the annual value of the crop was $20,000,000.  Then the fall began and by 1914 India was producing only $300,000 worth!  What had happened to destroy this profitable industry?  Some blight or insect?  No, it was simply that the Badische Anilin-und-Soda Fabrik had worked out a practical process for making artificial indigo.

That indigo on breaking up gave off aniline was discovered as early as 1840.  In fact that was how aniline got its name, for when Fritzsche distilled indigo with caustic soda he called the colorless distillate “aniline,” from the Arabic name for indigo, “anil” or “al-nil,” that is, “the blue-stuff.”  But how to reverse the process and get indigo from aniline puzzled chemists for more than forty years until finally it was solved