^44 Acciunt offome Galvanic Comh'mationt. 



flic apparatus evolving hidrogen ; and the wire attached to the end a£ling on the fulphuret, 

 depofiting oKide when compofed of filver, and generating oxigen when of gold. 



V. In all the fingle metallic piles conflruxSled with cloths, the a£lion is very tranlient: 

 the decompofiiion of the acids, and of the fulphurets, is generally completed in a few mi- 

 nutes; and, in confequence, the Galvanic influence ceafes to be evolved. The arrange- 

 ment of all the different feries may, however, (by means of an apparatus conftru^ed after 

 the ideas of Count Rumford,) be made in fuch a manner as to give confiderable perma- 

 nency to their effefts. This apparatus is a box, covered with cement incapable of con- 

 <iu£ling eleftricityj and compofed of three pieces of mahogany, each containing grooves 

 capable of receiving the edges of the different plates proper for compofing the feries. One 

 half of thefe plates muft be compofed of horn, or glafs, and the other half of metallic fub- 

 flances ; and the conduftors of eledlricity, and the non-condu£tors, muft be alternately 

 cemented into the grooves, fo as to form water-tight cells. 



When the apparatus isufed, thefe cells are filled, in the Galvanic order, with different 

 folutions, according to the clafs of the combination; and conneflcd in pairs with each 

 other, by flips of moiftened cloth, carried over the non-conduQing plates. 



A combination of fifty copper- plates, arranged in this manner, with weak folutions of 

 nitrous acid, or nitrate of ammaniac, and fulphuret of pot-afh, gives pretty flrong fiiocks, 

 rapidly evolves gas from water, and afFefts the condenfing eleftroracter. 



It does not lofe its power of a£tion for many hours; and, when this power is loft, it 

 may be reftored by the addition of fmall quantities of concentrated folutions of the prober 

 chemical agents to the fluids in the different cells. 



From two experiments made on copper and filver, it would appear, that the fingle me- 

 tallic batteries adl equally well, wlien the metals made ufe of are flightly alloyed, and 

 w4icn they are in aftate of purify. 



VI. 



^hfi'ruat'tons and Experiments undertalen ivith a View to determine the Qjtaniity of Sulphur 

 tontained in Sulphuric ^ciJ ; and of this latter contained in Sulphates iu general*. By 

 Richard Chenevix, E/q. f. R. S. and M.R.I. A. 



I 



N a paper which I had theTionour to prefent to the Royal Society of London, and the 

 fubje£l of which was the analyfis of fome arfeniates of copper, and of iron, i had occafion, 

 in examining many pyrites, matrices of thofe ores, to remark the very great inequality 

 which prevailed in the refults of repeated experiments, made with a view to determine 

 fhe proportion of fulphur. But I (bon perceived, that the inaccuracy was caufed by a 

 partial combuftion and acidification of the radical, through the means of the nitric acid^ 

 •employed to diflblve the ore. 



* Iriih Academy, 1801. 



> Having 



