K)ii THE OXIDE OP IROK. 353 



feoiled witli the latter in two distinct and equal portions. 

 The prussiate of potash thus obtained is, however, mixed 

 Vith a much larger quantity of hidroguretted sulphuretthan 

 when a greater portion of Prussian blue is employed. 



Whether the prussous acid can be applied to any use, ^^.^ °^ ^^* 

 time and future experiments must decide. It appears to me 

 to be a very delicate test of silver and of iron in solution. 



The preceding experiments, by proving the presence of The prussic 



., • ., . 1 • ii -J ■. acid contains 



oxigen m prussic acid, give it a stronger claim than it be- moreoxigen 

 fore possessed for being placed among the acids. 



The prussous acid possessing stronger acid properties but is less acid 

 than the prussic is a curious, though not a solitary, instance ^^ ^ 

 of the eft'ect of oxigen in diminishing acidity, when its quan- 

 tity exceeds a certain fixed proportion; in this respect the 

 prussic acid is analogous to the oximuriatic. 



To recur to the attempt which gave rise to the researches Pure triple 

 that are the subject of this memoir, I beg leave to state, P™^^'^^® P''** 

 that I have succeeded in producing pure triple prussiate of 

 potash, by stopping the process before the change which 

 produced the prussite ensued ; and by subsequent purifica- 

 tion of the lixivium from sulphates and sulphites, by ace- 

 tate of barytes; from sulphur by acetate of lead; and, 

 lastly, from the acetate of potash thus formed by crystal- 

 lization; but on account of the complication of this pro- 

 cess, I hesitate to recommend it for general use, 



ROBERT PORRETT, Jun. 



Tower, London, April ^1, 1809. 



VI. 



0?t the Oxides of Iron, and the Marnier in zchich they com- 

 port themselves with sortie Acids. By Mr. Bucholz *. 



JL HE little agreement among chemists with respect to the Proportion of 

 proportions of oxigen in oxides of iron induced Mr. Bu- oxldesnot se?- 

 cholz to make these experiments. He employed for the tied. 

 purpose bright iron wire of the greatest purity. 



* Annales de Chimie, vol. LXV, p. 202. Abridged from 

 Gehlen's Journal by Mr. Vogel. 

 Vol. XXV»--Suppi-EMENi:. 2 A A. Experiments 



