32 PRUSSIC AdD. 



Obfervatlonsre-reafon to conclude that the former is combined with water 1 , 

 fpefting gal- which we have to believe that it is contained in metals : 

 vamfin, &c yy^at then becomes of it when the water is decompofed, if, 

 as he imagines, the electric, or " galvanic phenomena, en- 

 tirely depend upon the metal undergoing a chemical change/' 

 1 muft confefs I cannot conjecture : but, in truth, it is en- 

 tirely the caufe of all the phenomena which take place: the 

 quantity afforded by the metal, fo very fmail a portion of 

 which undergoes any chemical change, muft be too trifling to 

 be confidered; for if any more tlian the oxidated part of the 

 metal contributed, the quantity of the metal in the plates, as 

 well as the extent of its furface, would in fome degree hava 

 an effeft : but this, as I alledged, is not the cafe ; and, there- 

 fore, Mr. W.'s fanciful conjecture, that there is as it were a 

 fpring of ele&ric fluid in the metal, as a refource for a fup- 

 ply, although very ingenious, may be regarded as a perfecl 

 hypothecs — a fuppofition unfupported by any fact; and as 

 an inftance, from his partiality for it on this occafion, of our 

 difpofition to overlook im perfections in our own performances, 

 whilft we obferve them in the works of others. 

 I am, Sir, 



Your moft obedient fervanf, 



RA. THICKNESSE. 



IX. 



Abftrac~t of a Memoir on the Poffibility of obtaining Prujfiate of 

 Potajh free from Iron ; the Unalter ability of the PruJJic Acid 

 at high Temperatures ; and the true Nature of the Combina- 

 tions of this Acid with different Bafes. By Bucholz. 



(Concluded from p. 2S2, Vol. IX.) 



General deduc- JL HESE two experiments therefore prove, that from four 

 parts of dried blood and one of carbonate of potafh, no more 

 prufljated alkali can be obtained than from two of blood and 

 one of alkali. 



From what has been fo far ftated the author concludes, after 

 varying and repeating the experiments here detailed, 



I. That 



