2j6' analysis, 



Defcnptlon and fenfiblv diminlftied. But if after edulcoratlon it be diflblvfet! 

 aiialyfisof a . . . . , , „ , , , , . . 



mtneral from '" "'^""^c acid, and potafh be added, no precipitate is pro 

 Coniwall, duced. 



Carbonate of potafh caufes a white precipitate when 

 dropped into the aqueous folution of the fcaly fublimate. 



The fupernalant fluid was poured off and gradually evapo- 

 rated, but it became repeatedly turbid, nor could I by means 

 either of the filter or alcohol prevent a recurrence of the fame 

 effed. Nearly the fame refult takes place when carbonate of 

 ammonia is ufed as the precipitant. 



Some of the white fcales were moiflened with futphuric acid. 

 Nb vapour arofe. 



Some of the precipitate obtained by means of carbonate of 

 potalli from the watery folution of this fubftance, was, after 

 fufficient edulcoration, diffolved in fulphuric acid ; the folution, 

 on due evaporation, produced permanent cryftals, feme of 

 which refembled alum, but others feemed to differ from it in 

 external chara6ler. Ammonia decompofed the folution of 

 them in water, and a few drops of liquid potaQi diffolved the 

 precipitated earth. The quantity was too fmall for farther 

 experiment. 



If diftilled water be poured into the retort and bailed in it, 

 fo as to diOblve what adheres to the neck and cavity of it, a 

 further folution is effefted, but differing in fome raeafure from 

 the folution of the fublimate colle6ted from the neck of the 

 veffel. This latter folution is found to contain lead. If nitric 

 or muriatic acid be poured into the retort, fo as to diffolve 

 what Jlill remains adhering to it, the prefence of lead becomes 

 more evident. Whence does this metal arife? I have reafon 

 to believe that it arifes from the glafs retort, which is corroded 

 by the acid of the foffil extricated by heat. But what acid is 

 it? It does not feem to be either the phofphoric or fluoric 

 acids, the latter of which became the firft objeft of my fuf- 

 picion. 



The opinion which Mr. Davy fuggefled to me feems more 

 probable, that it is of vegetable origin. Oxalic acid, on the 

 authority of Bergman, may be volatilized ; yet fome of its 

 properties are very extraordinary and do not accord with this 

 idea. 



I decompofed the watery folution of the fcales by nitrate of 

 'Jead, and after a fuflicient edalcoration of the fubfided precipi- 



Ute 



