204, Refearchcs refpeSllng. 



and C, in which a deliqucfcent calcareous fait was put into 

 action with the fulphate of pota(h, correfponds exactly with 

 the difference of folubility which exifts between the fulphate 

 of lime and the fulphate of magnefia. 



9. After having treated of faline fubftances in the preced- 

 ing experiments, as if thev formed feparate or diftinct com- 

 binations in a liquid, I (hall now confide r fome effects which 

 are owing to the mutual action which is in reality exerted 

 bv them all when they are mixed in this (late. 



O. An aqueous folution of acetite of lead was gradually 

 poured into a folution of muriate of foda, till no more pre- 

 cipitate was produced. The liquid which remained above 

 the precipitate flrongly reddened blue paper, which effect 

 was not produced by the mere folution of the acetite ot lead, 

 nor by the muriate of foda; but it aflumed a deep colour 

 with hydro-fulphurets, and afforded an abundant precipitate 

 with the muriatic and fulphuric acids. During its evapo- 

 ration a depofition was formed of a fcarcely foluole muriate 

 of lead; and alfo a crufl which had not a cryftalline ap- 

 pearance. Laftly, fome fine cryftals were obtained, which 

 were an acetite of foda and an oxide of lead. On diffoiving 

 the faline cruft, a depofition took place of muriate of lead 

 with excels of oxide, analogous to that defcribeu by Vau- 

 quelin. (Annates de Chimie, torn, xxxi.) It was neceffary to 

 repeat the folution and cryftallization feveral times before the 

 depofition ceafed ; and the faline cruft thus became divided 

 into two fubftances, muriate of foda and muriate of lead, 



If the muriatic acid remain engaged in the liquid together 

 with the acetous, as both acids are volatile, the excefs, which 

 is but (lightly engaged, and which may be expelled by the 

 action of heat, muft be compofed of two acids. In fact, 

 having ditlilled a mixture fimilar to the preceding, after 

 having feparated the depofition which was firft formed, the 

 liquid which pafled into the receiver contained acetous and 

 muriatic acid: this circumftance deierves particular atten- 

 tion, and ferves.to explain feveral phaenomena. 



10. C. Prieur has remarked that when lead was employed 

 to purify a folution of filver mixed with muriatic acid, a part 

 of the latter acid pafled over by diftillation. This takes place 

 hecaufc the muriate of lead is foluble, and much fo by the 

 action of the nitric acid. The liquid is therefore compofed 

 of oxide of lead, muriatic acid and nitric acid. The oxide 

 of had divides its action upon the two acids, and both are 

 fubjected to the action of the cxpanfibility produced by the 

 heat. 



If the fulphuric acid were to be retained, lead would be 



an 



