no Galvanic Batteries. 



MISCELLANIES. 



DOMESTIC AND FOREIGN. 



1 . Mr. Faraday on the most improved form of the Galvanic De- 

 flagrator, especially as constructed by Dr. Hare. — More than sixteen 

 years have elapsed since an account was given in this Journal by Dr. 

 Hare of his galvanic deflagrators, and of their great poveer in pro- 

 portion to their size in producing intense ignition. Not long after, 

 the experiments of Dr. Hare were with some additions repeated by 

 us, and the results fully confirming the allegations of the inventor 

 were also published in this work. Although Dr. Hare's memoirs 

 and ours with engravings were published in the Annals of Philoso- 

 phy and Philosophical Magazine, London, yet it does not appear 

 that his deflagrators were imitated in Europe, the old and inferior 

 constructions continuing in general use. It is satisfactory to find 

 from the following abstracts from a paper of Mr. Faraday, that the 

 course of his investigations has led him latterly to consider the defla- 

 grator of our countryman as the most efficient form of a galvanic 

 series. We quote those passages of Mr. Faraday's paper on the 

 subject of the deflagrator which tend to justify our statement. 



Alluding to the principles which this distinguished author had con- 

 sidered as established by his investigations, he uses the following 

 language. 



" Guided by these principles, I was led to the construction of a 

 voltaic trough in which the coppers passing round both surfaces of 

 the zincs as in Wollaston's construction should not be separated from 

 each other except by an intervening thickness of paper, or in some 

 other way so as to prevent metallic contact, and should thus consti- 

 tute an instrument compact, powerful, economical, and easy of use. 

 On examining however what had been done before I found that the 

 new trough was in all essential respects the same as that invented and 

 described by Dr. Hare, Professor in the University of Pennsylvania, 

 ts whom I have great pleasure in referring it. 



" Dr. Hare has fully described his trough.* In it the contiguous 

 copper plates are separated by thin veneers of wood, and the acid is 

 poured on to or oif the plates by a quarter revolution of an axis, to 



* Philosoph. Magazine, 1824, Vol. lxiii. p. 271, or Sillitnan's Journal, Vol. vir. 

 See also a previous paper by Dr. Hare, Annals of Philosophy, [second series,] 

 1821, Vol. I. p. 329. Also Phil. Mag. [first series,] Vol. lvii. p. 289, in which h&. 

 speaks of the non necessity of insulation between the coppers. 



