THE DEBT TO PURE SCIENCE 31 



Sixty years ago an obscure German chemist obtained an 

 oily liquid from coal tar oil, which gave a beautiful tint with 

 calcium chloride; five years later another separated a similar 

 liquid from a derivative of coal tar oil. Still later, Hofmann, 

 then a student in Liebig's laboratory, investigated these sub- 

 stances and proved then- identity with an oil obtained^ long 

 before by Zinin from indigo, and applied to them all Zinin's 

 term, aniline. The substance was curiously interesting, and 

 Hofmann worked out its reactions, discovering that with 

 many materials it gives brilliant colors. The practical appli- 

 cation of these discoveries was not long delayed, for Perkins 

 made it in 1856. The marvelous dyes, beginning with ma- 

 genta and solferino, have become familiar to all. The aniline 

 colors, especially the reds, greens, and blues, are among the 

 most beautiful known. They have given rise to new indus- 

 tries and have expanded old ones. Their usefulness led to 

 deeper studies of coal tar products, to which is due^ the dis- 

 covery of such substances as antipyi'in, phenacetin, ichthyol, 

 and saccharin, which have proved so important in medicine. 



One is tempted to dwell for a little upon meteorology, 

 that border land where physics, chemistry, and geology meet, 

 and to speak of the signal service system, the outgrowth of 

 the studies of an obscure school teacher in Philadelphia, but 

 the danger of trespassing too far upon your endurance makes 

 proper only this passing reference. 



While men of wealth and leisure wasted their energies in 

 literary and philosophical discussions respecting the nature 

 and origin of things, William Smith, earning a living as a land 

 surveyor, plodded over England, anxious only to learn, in no 

 haste to explain. His work was done honestly and slowly; 

 when finished as far as possible with his means, it had been 

 done so well that its publication checked theorizing and brought 

 men back to study. .His geological map of England was 

 the basis upon which the British survey began to prepare the 

 detailed sheets showing Britain's mineral resources. 



In our country Vanuxem and Morton early studied the 

 New Jersey Cretaceous and Eocene, containing vast beds of 

 marl. Scientific interest was aroused, and eventually a 

 geological survey of the state was ordered by the legislature. 



