THE 



PHILOSOPHICAL MAGAZINE 

 AND JOURNAL. 



S0 th APRIL 1824. 



XXXIX. Letter from Robert Hare, M.D. Professor of Che- 

 mistry in the University of Pennsylvania, to B. Silliman, 

 Professor of Chemistry in Yale College, on some improved 

 Forms of the Galvanic Deflagrator ; on the Superiority of its 

 deflagrating Power : Also, an Account of an improved Single- 

 leaf Electrometer ; of the Combustion of Iron by a Jet of 

 Sulphur in Vapour ; and of an easy Mode of imitating native 

 Chalybeate Waters* 



A FTER I had discovered that the deflagrating power of a 

 ■^"*- series of galvanic pairs was surprisingly increased by 

 their simultaneous exposure, after due repose, to the acid, va- 

 rious modes suggested themselves of accomplishing this ob- 

 ject. In the apparatus which I sent you, the coils, being all 

 suspended to two beams, could be lowered into troughs con- 

 taining the acid. In another apparatus, of which I afterwards 

 gave you an account, with an engraving for your Journal, the 

 troughs containing the acid were made to rise, so that all the 

 plates might be immersed at once. A better mode has since 

 occurred to me. Two troughs are joined lengthwise, edge to 

 edge, so that when the sides of the one are vertical, those of 

 the other must be horizontal. Hence, by a partial revolution 

 of the two troughs, thus united, upon pivots which support 

 them at the ends, any fluid which may be in one trough must 

 flow into the other, and, reversing the motion, must flow 

 back again. The galvanic series being placed in one of the 

 troughs, the acid in the other, by a movement such as above 

 described the plates may all be instantaneously subjected to 

 the acid, or relieved from it. The pivots are made of iron, 

 coated with brass or copper, as less liable to oxidizement. A 

 metallic communication is made between the coating of the 

 pivots and the galvanic series within. In order to produce 

 a connexion between one recipient of this description, and 



* From a tract reprinted, with corrections and additions, from Silliman's 

 Journal, No. 1. vol. vii. and published at Philadelphia; with a copy of 

 which we have been favoured by the author.— Edit. 



Vol. 63. No. 312. April 1824. H h another, 



