WRITINGS OF JAMES SMITH60N. 57 



sulphate of soda, and correspond to 1.86 grains of it in an 

 arid state, or uncombined with ice.* 



10 grains of the saline part of this native salt would have 

 produced 1.12 grains of ignited muriate of silver (k). By 

 accurate experiments 241 grains of ignited muriate of silver 

 have been found to correspond to 100 grains of ignited mu- 

 riate of soda.f 



Consequently the soluble portion of the present Yesuvian 

 salt consists of 



Sulphate of potash 7.14 



Sulphate of soda 1.86 



Muriate of soda - - 0.46 



Muriate of ammonia ^ 



Muriate of copper V - 0.54 



Muriate of iron ) 



10.00 



t. The insoluble sandy residue (g) having been thoroughly 

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

 tion formed without any effervescence. Acetate of barytes 

 scarcely rendered this solution turbid ; but nitrate of silver 

 produced a copious curd-like precipitate, and iron abund- 

 antly threw down copper from it. The green grains enclosed 

 in this native sulphate 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 inclined to believe this yellow powder to be a submu- 

 riate of iron, but its small quantity, and the admixture of 

 the submuriate of copper, were impediments to entirely 

 satisfactory results. Such a submuriate of iron, though, if 

 I mistake not, overlooked by chemists, exists, for the pre- 

 cipitate which oxygen occasions in solution of green muriate 

 of iron, contains marine acid. 



*Prof. KLAPROTH'S Essays, Vol. 1, p. 282. 

 f Dr. HENRY, Phil. Trans. 1810. 



