ON THE NATURE OF *RECIPITAT»$. 193 



XI. 



Obfcrvations on the real Nature of tlie Precipitates formed hy the 

 Prujfiates in Acid Solutions ofBarites, and the Affinities of the 

 Prujfic Acid *. % Citizen Guyton, 



JDERGMAN announced, that the acid folutions ofbarites Precipitat!on of 

 are precipitated by the faturated Pruffian alkali. This facl, fi " n nllp j co r n ." 

 confirmed by the obfcrvations of a great number of chemifts, fidered as an in- 

 appeared to many as a new indication of its metallic nature, Jj"^" ° nz ^ u 

 already fufpected on account of its great weight. Lavoifier in 

 particular thought it very probable, that the difficulty of re- 

 ducing it to the metallic ftate proceeded from its having more 

 affinity with oxigen than carbon f . 



The little fuccefs of the attempts to effect this reduction This notio» 

 having in fome meafure caufed the notion of this compofition abandoned » 

 to be abandoned, the attention was again fixed by the pheno- 

 menon of the precipitation of an earth by a re-agent, which 

 according to the generally received opinion, afforded a cha- 

 racteriftic indication of the prefence of a metal. 'It was then 

 fu (peeled to be owing to fome accidental caufe. M. Meyer and the precipi- 

 of Stetin, announced in 1786, in Crell's Annals, that ^ S^ l tf JShf j 

 prnlliate of potafti, if very pure and carefully prepared, did 

 not precipitate barites from its folutions. Kirwan and Klap- 

 roth adopted this opinion from their own experiments. Mod 

 chemifts however continued to believe that the precipitation 

 took place, whatever might be the means of purification of 

 the proof liquor. Pelletier, amongfr others, fuppofed it one 

 of the moft effential diftinclive characters of barites and ftron- 

 tian J. 



Some time ago being defirous to try a pruffiate of lime re- Carbonate of 

 cently prepared with lime of marble, and very clear, I poured P° tartl pr ffi lp '" rf 

 into it a folutiott of carbonate of potafh. The liquor inftantly lime, 

 became milky and opake. As it is certain that no metallic 

 lubftance was prefent, I could only attribute this decompofi- 



* Read at the fitting of the clafs of Philofophical and Mathe- 

 matical Sciences of the Inftitute, the 2d Thermidor in the year 

 10, and inferted in the Annales de Chimie, XLIII. 185. 



f Traite Elementaire, &c. Vol. I. p. 174. 



| Mem. de Chimie, Vol. II. p. 454. 



Vol. III.— November, 1S02. Q tioa 



