In this search for substances that would attack a specific disease germ one of the leading investigators was Prof.  Paul Ehrlich, a German physician of the Hebrew race.  He found that the aniline dyes were useful for staining slides under the microscope, for they would pick out particular cells and leave others uncolored and from this starting point he worked out organic and metallic compounds which would destroy the bacteria and parasites that cause some of the most dreadful of diseases.  A year after the war broke out Professor Ehrlich died while working in his laboratory on how to heal with coal-tar compounds the wounds inflicted by explosives from the same source.

One of the most valuable of the aniline antiseptics employed by Ehrlich is flavine or, if the reader prefers to call it by its full name, diaminomethylacridinium chloride.  Flavine, as its name implies, is a yellow dye and will kill the germs causing ordinary abscesses when in solution as dilute as one part of the dye to 200,000 parts of water, but it does not interfere with the bactericidal action of the white blood corpuscles unless the solution is 400 times as strong as this, that is one part in 500.  Unlike carbolic acid and other antiseptics it is said to stimulate the serum instead of impairing its activity.  Another antiseptic of the coal-tar family which has recently been brought into use by Dr. Dakin of the Rockefeller Institute is that called by European physicians chloramine-T and by American physicians chlorazene and by chemists para-toluene-sodium-sulfo-chloramide.

This may serve to illustrate how a chemist is able to make such remedies as the doctor needs, instead of depending upon the accidental by-products of plants.  On an earlier page I explained how by starting with the simplest of ring-compounds, the benzene of coal tar, we could get aniline.  Suppose we go a step further and boil the aniline oil with acetic acid, which is the acid of vinegar minus its water.  This easy process gives us acetanilid, which when introduced into the market some years ago under the name of “antifebrin” made a fortune for its makers.

The making of medicines from coal tar began in 1874 when Kolbe made salicylic acid from carbolic acid.  Salicylic acid is a rheumatism remedy and had previously been extracted from willow bark.  If now we treat salicylic acid with concentrated acetic acid we get “aspirin.”  From aniline again are made “phenacetin,” “antipyrin” and a lot of other drugs that have become altogether too popular as headache remedies—­say rather “headache relievers.”

Another class of synthetics equally useful and likewise abused, are the soporifics, such as “sulphonal,” “veronal” and “medinal.”  When it is not desired to put the patient to sleep but merely to render insensible a particular place, as when a tooth is to be pulled, cocain may be used.  This, like alcohol and morphine, has proved a curse as well as a blessing and its sale has had to be restricted because of the many victims to the habit of using this drug.  Cocain is obtained from the leaves of the South American coca tree, but can be made artificially from coal-tar products.  The laboratory is superior to the forest because other forms of local anesthetics, such as eucain and novocain, can be made that are better than the natural alkaloid because more effective and less poisonous.