

JOURNAL 



NATURAL PHILOSOPHY, CHEMISTRY 



AND 



THE ARTS. 



JULY, 1807. 



ARTICLE I. 



Fads toicard a History of Prussiates. By Mr. Proust.*- 



JL HE Prussian blue of the shops is seldom pure, as Impurities of 

 Scheele had already observed. Frequently, beside the alu- Prussian b!ue 

 mine which makes a part of it, we find silex, carbonate 

 and sulphate of lime, sulphate of potash, phosphate and 

 Ted oxide of iron, sulphur, ammonia not divested of animal 

 oil, &c. To study the nature of this combination therefore, 

 it is indispensable, to use only a prussiate free from alum, 

 and sufficiently edulcorated with acids and boiling water. — 

 It even appears, according to a remark of Berthollet, that Prussiate or 

 the prussiate of potash can attach itself to the Prussian blue P otastl 

 ho forcibly as to resist ablution to a certain degree. I do not essential to 

 not think with him however, that the surcharge of this salt supposed, 

 should be considered as an element essential to it; for when 

 the blue has been well prepared, and such is to be met with 

 In the shops, it leaves no trace of saline matter in the resi„ 

 duum after distillation. 



Prussian blue prepared without alum has a coppery ap- Pure Prussian 

 pearance like the best indigo. It loses only forty-five per ue ' 

 cent by combustion. Its residuum is red oxide of iron 

 without any mixture of foreign matter. 



* Annates de Chimie, Vol. LX. p. 185, Nov* 1806. 

 Vol. XVII.— July, 1807. H Action 



