Wells & Foote — One Hundred Years of Chemistry. 261 



thirty years. Among the first of these contributions was 

 a most vigorous but well-merited attack upon a Doctor 

 Clark of Cambridge, England, who had copied his inven- 

 tion without giving him proper credit. He begins (2, 

 281, 1820) by saying: "Dr. Clark has published a book 

 on the gas blowpipe in which he professes a sincere desire 

 to render everyone his due. That it would be difficult for 

 the conduct of any author to be more discordant with 

 these professions, I pledge myself to prove in the fol- 

 lowing pages." 



Hare also invented a galvanic battery which he called 

 a " deflagrator, " consisting of a large number of single 

 cells in series. With this, using carbon electrodes, he 

 was able to obtain a higher temperature than with his 

 oxy-hydrogen blowpipe. He was the first to apply gal- 

 vanic ignition to blasting (21, 139, 1832), and he first 

 carried out electrolyses with the use of mercury as the 

 cathode (37, 267, 1839). In this way he prepared 

 metallic calcium and other metals from solutions of their 

 chlorides, while the principle employed by him has in 

 recent times been used as the basis of a very important 

 process for manufacturing caustic potash and soda. 



Silliman, who had become an intimate friend of Hare 

 during two periods of chemical study under Woodhouse 

 in Philadelphia in 1802-1804, and who soon afterwards 

 spent fourteen months as a student abroad, chiefly in 

 England and Scotland, took a broad interest in science 

 and gave much attention to geology as well as to chem- 

 istry. In spite of this divided interest and his work as 

 a teacher, popular scientific lecturer, and editor, he found 

 time for a surprising amount of original chemical work. 

 For instance, using Hare's deflagrator, he showed that 

 carbon was volatilized in the electric arc (5, 108, 1822) ; 

 he was the first in this country to prepare hydrofluoric 

 acid (6, 354. 1823), and he first detected bromine in one of 

 our natural brines (18, 142, 1830). 



Atomic Weights. 



As soon as the atomic theory was accepted, the relative 

 weights of the atoms became a matter of vital importance 

 in connection with formulas and chemical calculations. 

 In advancing his theory, Dalton had made some very 

 rough atomic weight determinations, and it has been men- 

 tioned already that Berzelius, at the time that our histor- 



