536 THE POPULAR SCIENCE MONTHLY. 



tion has been made out." Within a few years chemists have an- 

 nounced the synthesis of many acids, essential oils, alkaloids, gluco- 

 sides, dye-stuffs, and other bodies naturally occurring in the organic 

 world, and so rapidly do these announcements succeed one another 

 that expectation has displaced surprise. Noteworthy are the follow- 

 ing : Alizarine, the valuable coloring-matter of madder ; vanilline, the 

 aromatic principle of the vanilla bean ; cu marine, the aromatic prin- 

 ciple of the Tonka bean ; indigo, the well-known dye-stuff ; uric acid, 

 an animal product ; tyrosin, likewise a product of the animal organism ; 

 salicine, daphnetine, and umbelliferone, natural glucosides and related 

 bodies ; piperidine, a constituent of pepper ; and cocaine, the new 

 anaesthetic. Besides these, many syntheses have been accomplished of 

 bodies isomeric and not identical with the natural products. 



The alchemists labored to transmute base metals into noble ones, 

 and were destined never to realize their ambitious designs ; modern 

 organic chemists, operating on substances compared with which even 

 the base metals are precious, jDroduce articles more beneficial to man- 

 kind than gold itself, and, at the same time, gain, indirectly, no small 

 store of the coveted metal. 



The application of chemistry to physiology encounters the most 

 complex and difficult problems in the science, and at the same time 

 aims to accomplish the most beneficent results. " The physiologist 

 complains that probably ninety-five per cent of the solid matters of 

 living structures are pure unknowns, and that the fundamental chemi- 

 cal changes which now occur during life are entirely shrouded in mys- 

 tery. It is in order that this may no longer be the case that the study 

 of carbon compounds is being so vigorously prosecuted." It may seem 

 strange to the non-professional in this audience that, in spite of per- 

 sistent and skillful attempts to solve the problem, chemists are obliged 

 to admit ignorance of the exact composition of so common a substance 

 as the white of egg ; yet, until they acquire an accurate knowledge of 

 the constitution of albuminous substances, the processes of animal 

 economy can not be explained. While the physiologist, in some de- 

 gree, waits on the organic chemist for further developments, the latter 

 discovers and prepares novel bodies much faster than the physiologist 

 ascertains their influence on the animal economy. To the joint labors 

 of chemists and physiologists are due the blessings of anaesthetics, hyp- 

 notics, and other conquerors of suffering and disease. The anaesthetic 

 properties of cocaine, and the circumstances of their discovery, are 

 matters of popular knowledge. Within a twelvemonth, ethyl-urethane 

 has been added to the list of hypnotics. 



In recent years sanitary chemistry has acquired great importance, 

 and now occupies a distinctly defined field, including all that pertains 

 to the hygienic value of foods and beverages, their adulterations, and 

 their fraudulent substitutes ; questions of gas and water supply ; of 

 the uses and abuses of disinfectants ; of household ventilation, and of 



