184 STEVENSON. 



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 stu- 

 dent in Liebig's laboratory, investigated these substances and 

 proved their identity with an oil obtained long before by Zinin, 

 from indigo, and applied to them all Zinin's term, Anilin. 

 The substance w^as curiously interesting and Hofmann worked 

 out its reactions, discovering that with many materials it gives 

 brilliant colors. The practical application of these discoveries- 

 was not long delayed, for Perkins made it in 1856. The mar- 

 velous dyes, beginning with Magenta and Solferino, have be- 

 come familiar to all. The anilin colors, especially the reds, 

 greens and blues, are among the most beautiful known. They 

 have given rise to new industries and have expanded old ones. 

 Their usefulness has led to deeper studies of coal-tar products,, 

 to which is due the discovery of such substances as antipyrin,, 

 phenacetin, ichthyol and saccharin, which have proved so im- 

 portant 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 studies by 

 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 lit- 

 erary and philosophical discussions respecting the nature and 

 origin of things, William Smith, earning a living as a land sur- 

 veyor, plodded over England, anxious only to learn, in no haste 

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

 finished as far as was 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 preparation of 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. 



