SKETCH OF ROBERT HARE. 697 



hibitions, while the intensity of the current was so low that hardly 

 a visible spark could be made to }:>ass by it through poles of car- 

 bon. The magnetic effects were afterward shown by Prof. Henry 

 to be attainable from a single cell, if combined with suitable con- 

 ductors. Instead of Cruikskank's cumbrous battery of alternat- 

 ing 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 sur- 

 face and its resultant power with a single roll of metal, and in 

 1820 introduced the denagrator, in which any series, however ex- 

 tended, could be instantaneously brought into action or rendered 

 passive, at pleasure. This apparatus consists of a large sheet of 

 copper having several hundred square feet of surface and a simi- 

 lar one of zinc, separated by a piece of felt or cloth saturated 

 with acidulated water, and then rolled up in the form of a cylin- 

 der. Faraday bore testimony, in his Experimental Researches, 

 to the merit of this invention when, in 1835, he acknowledged 

 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 results 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 considerable time before 

 it was fully credited. It was with these batteries 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 detect- 

 ing minute quantities of opium in solution. He was interested, 

 too, in the discussions of philosophical chemistry, as was most 

 notably shown in the earnestness with which he contested what 

 he conceived were the errors of the salt radical theory. 



He made studies in meteorology, and had a theory of whirl- 

 winds and storms founded on an electrical hypothesis, which he 

 opposed to the rotary theory of W. C. Redfield. At the second 

 meeting of the American Association for the Advancement of 

 Science he explained his own views on this subject, while he con- 

 troverted those of Mr. Redfield. This gentleman was present and 

 heard his remarks, but made no reply then. He was not a speaker, 

 and did not address the public except in writing. 



In 1818 Dr. Hare was chosen Professor of Chemistry and Nat- 

 ural Philosophy in William and Mary College, and in the same 

 year was made Professor of Chemistry in the medical department 

 of the University of Pennsylvania. He held the latter position 

 till 1817. His teachings were marked by the originality of his 



