ON THE PURITY OF THE FIXED ALKALIS, 35 



barytes, taking care to vise a little excess; filtered; and 

 evaporated quickly to dryness. Half of the residuum was 

 put into alcohol, and treated as usual. The other half was 

 dissolved in barytes water. The liquor, containing but a 

 slight excess of barytCo, was filtered, speedily evaporated, 

 and fused in a silver crucible at a cherry red heat, as the 

 portion prepared with alcohol had been. 



Of these two specimens, 100 parts of that prepared with The latter 

 alcohol required 119*6 of concentrated acid for their satura- most acid, 

 tion ; and 100 of the other took 122^i of acid. These re- 

 sults confirm the preceding; and appear to demonstrate, 

 that the soda prepared with alcohol contains only 0*71 or 

 0'72 of such alkali, as in the subcarbonate and sulphate of 

 soda is neutralized by carbonic and sulphuric acid. 



Similar experiments repeated in the same way, substitut- Similar trials 

 ing for the soua caustic potash prepared with alcohol, and J|^,^ s'imUar 

 for the carbonate and sulphate of soda the corresponding results. 

 salts with base of potash, afforded analogous results; and 

 authorize me to conclude, that potash prepared with alcohol, 

 far from being pure potash, contains only 0*72 or 0*73 of 

 real alkali. 



If these experiments be accurate, it follows, that potash These facts re^ 

 and soda prepared withalcoliol cannot be employed to ascer- ^jon of many 

 taiu by synthesis the proportions of the constituent princi- analyses. 

 pies of saline substances, that have these alkalis for their 

 base. This is an important corollary, since it requires a re- 

 vision of many experiments founded on this principle, in 

 order to correct their results; or at least to confirm the al- 

 terations, that so great a difference in the principal datum 

 must occasion. 



Among the examples I might adduce, I shall select such Instances m 

 as appear to me best fitted to establish the truth of this analyst of dif- 

 position. In the year 10 Mr. Vauquelin published an im- ferent sorts of 

 portant essay on the analysis of different kinds of potash, ^*^ ^^ ' 

 and on the means of readily asceitaining the quantity of 

 pure alkali in them. In this paper, which has sylready been 

 so serviceable to the arts, both by its immediate application, 

 and by giving birth to the researches of Mr. Descroizilles, 

 the author, after having ascertained the quantity of nitric 

 acid of a known density necessary to neutralize a given 

 D 2 quantity 



