Mr. Nevins on theReduction of the Chlorides of Mercury. 431 



face of the iron ; that which I formed was of twenty plates : the 

 shock, without coils or condenser of any description, was so 

 powerful as to be scarcely tolerable. When a wire was scraped 

 along the edge of the plate at one extremity, the other hand 

 touching the opposite end, the decomposition of water was also 

 rapid, though I have not yet accurately measured its powers : 

 its action continued unabated for nearly three hours without 

 the addition of any acid or sulphate. If greater constancy 

 be required, the alternate cells can be filled up with coarsely 

 powdered sulphate, and some added as required. I was fearful 

 that upon a second trial the intensity would have much abated, 

 in consequence of the oxidated surface of the plates prevent- 

 ing so uniform a deposition of the precipitate, but was grati- 

 fied to find that, after having been suffered to dry and re- 

 main at rest for several days, its action was as intense and 

 constant as upon the first trial. The advantage of this form, 

 where series and sustained power are required, I consider to 

 be its extreme oeconomy, a single cheap metal being employed 

 instead of two expensive ones ; the greater durability of iron 

 as compared with zinc ; the cutting in squares, so that none is 

 wasted ; and the tiresome process of soldering being altogether 

 dispensed with. The diaphragms and solutions are common 

 to every form of constant battery: possibly very thin plates of 

 deal might do as well as porcelain; the durability of the latter 

 material, however, makes its expense unimportant. My ob- 

 ject in this communication is not so much to vaunt this parti- 

 cular form of battery as to direct increased attention to the 

 porous filter as likely to form an important element in the 

 analysis of the voltaic trough : it may possibly throw some 

 light upon the organization of the torpedo. 



floping you will consider this letter of sufficient importance 

 to merit insertion in the Philosophical Magazine, 



I remain, Gentlemen, yours, &c, 

 Swansea, Oct. 26, 1838. W. R. GroVE. 



LVII. On the Reduction of the Chlorides of Mercury iiohen 

 mixed -with Organic Substances. By John B. Nevins, Esq. 



To the Editors of the Philosophical Magazine and Journal, 

 Gentlemen, 



A SHORT time since Mr. West, Lecturer on Chemistry 

 -^^ at the Medical School in this town, mentioned to me the 

 fact, that if a mixture of Hg CI with some vegetable substances 

 be heated, metallic Hg is sublimed ; and recommended that 

 the circumstances upon which this depended should be ex- 



