148 IMPROVEMENT IN THE GALVANIC APPARATUS. 



It decomposes Glass, it is said in your Journal, is dissolved by the basis 



f aSS b- • a °^ P otasn m tne same manner as tlie metals. The real 

 with its aUcafi statement with regard to glass was, that the basis of potash 



into an oxide decomposed it by combining w'.th its alkali, and bv forming 

 with less oxt- , .. c , , .. . ,'• . 



ireri than pot- a rccl oxlde ot a less degree ot oxygenation than potash, 



ash. which oxide was likewise procured. by other means. 



Spec. grav. of It is stated, that the specific gravity of the basis of soda 



&td a b o-9 of is to that of water as 7 10 10, Mr * Ddy y sald ' as 9 to 10, 



I am, Sir, with great respect, 



Your obedient humble servant, 



A CHEMIST. 



XI. 



An Improvement in the Galvanic Trough, to prevent the Ce- 

 ment from being melted, when the Action is very powerful. 

 Communicated by a Correspondent. 



SIR? To Mr. NICHOLSON. 



Cement of tne JL HE superiority of galvanic batteries constructed on the 

 trough hable principle of Volta's couromie des tasses, as recommended 

 to be melted bv Mr. Wilkinson, is, I believe, fully established. One in- 

 evolveV at convenience however attends it: the action of the acid on 

 the zinc plates being greatly increased, the quantity of ca- 

 loric evolved is fo considerable, as frequently to melt the ce- 

 ment with which the wooden partitions of the troughs are 

 This may be covered. To remedy this inconvenience, I have had recourse 



remedied by t | agg petitions, and rind them answer mv expectations 



making the . 



partitions of completely. Tj; is better to make them so much larger than 



glasi. t ^ e 1Tie ta.llic plates, as to leave a space of about half an inch 



(it should not I think be less) between the sides and bottom 

 of the trough, and metallic plates. Common crown glass 

 is perfectly adapted to the purpose: its thickness, of course, 

 must be proportioned to the size required ; and the top edge 



This battcrv should be around smooth. A batterv constructed on this 



, .■ , o * . . 



to^r-aYin en I >lan ma y be excited to great intensity, without injuring the 

 sity. cement at all. 



I have the honour to be, Sir, 



Your obedient servant, J. G. C. 

 TunbridgCyJan.Zl, 1808. 



XII 



