i;8 PIONEERS OF SCIENCE IN AMERICA. 



and plunging the whole at once into a tank of dilute acid. 

 Great magnetic and heating effects were obtained with this in- 

 strument, and it was many years before any other voltaic ap- 

 paratus was constructed'in which the movement of so great a 

 volume of heat was attained with so low a projectile or inten- 

 sive force. By it large rods of iron or platinum were ignited 

 and fused with splendid exhibitions, while the intensity of the 

 current was so low that hardly a visible spark could be made 

 to pass by it through poles of carbon. The magnetic effects 

 were afterward shown by Prof. Henry to be attainable from a 

 single cell, if combined with suitable conductors. Instead of 

 Cruikshank's cumbrous battery of alternating zinc and copper 

 plates, which Davy used in the experiments that resulted in 

 the discovery of the metallic bases of the alkalies, Hare found 

 a way of obtaining a corresponding amount of surface and its 

 resultant power with a single roll of metal, and in 1820 intro- 

 duced the deflagrator, in which any series, however extended, 

 could be instantaneously brought into action or rendered pas- 

 sive at pleasure. This apparatus consists of a large sheet of 

 copper having several hundred square feet of surface and a 

 similar one of zinc, separated by a piece of felt or cloth satu- 

 rated with acidulated water, and then rolled up in the form of 

 a cylinder. Faraday bore testimony, in his Experimental Re- 

 searches, to the merit of this invention when, in 1835, he ac- 

 knowledged that, having worked exhaustively to perfect the 

 voltaic battery, finding that Hare had anticipated him many 

 years before, and had accomplished all that he had attempted, 

 he at once adopted his instruments, as embodying the best re- 

 sults then possible. 



With one of Hare's deflagrators, Prof. Silliman, in 1823, 

 first demonstrated the volatilization and fusion of carbon, a 

 result then considered so extraordinary that it was a consider- 

 able time before it was fully credited. It was with these bat- 

 teries that the first application of voltaic electricity to blasting 

 under water was made in 1831 in experiments conducted under 

 Dr. Hare's direction. 



Dr. Hare was also distinguished in chemistry as the author 

 of a process for denarcotizing laudanum, and of a method for 

 detecting minute quantities of opium in solution. He was in- 

 terested, too, in the discussions of philosophical chemistry, as 

 was most notably shown in the earnestness with which he con- 



