s62 Mr. Smithson on a saline Substance, &c. 



edulcorated, dilute nitric acid was put to it. A green solution 

 formed without any effervescence. Acetate of barytes scarcely 

 rendered this solution turbid ; but nitrate of silver produced a 

 copious curd-like precipitate, and iron abundantly threw down 

 copper from it. The green grains enclosed in this native sul- 

 phate of potash, appear, therefore, to be a submuriate of 

 copper, of the same species as that of the green sands of Peru 

 and Chili. 



Muriatic acid dissolved the yellow ochraceous powder, and 

 prussiate of soda-and-iron produced Prussian blue. I am in- 

 clined to believe this yellow powder to be a submuriate of 

 iron, but its small quantity, and the admixture of the submu- 

 riate of copper, were impediments to entirely satisfactory re- 

 sults. Such a submuriate of iron^ though, if I mistake not, 

 overlooked by chemists, exists, for the precipitate which oxy- 

 gen occasions in solution of green muriate of iron, contains 

 marine acid. 



Possibly this yellow powder, and the crystals of speculary 

 iron which exist in this Vesuvian salt, have been produced by 

 a natural sublimation of muriate of iron, similar to that of the 

 experiment of the Duke d'AvEN, recorded by Mac^uer,* 

 and which was known long before to Mr. Boyle and Dr.^ 

 Lewis. -f 



Thiis Vesuvian salt, considered in its totahty, has presented 

 no less than nine distinct species of matters, and a more rigor- 

 ous investigation, than I was willing to bestow on it,, would 

 probably add to their number. 



July 3, 1813. 



• Diet, de Cbemie, Art. Ftr. 



f A course of practical chemistry by William Lewis, 1746, page 63, note/.. 



