? with the Prussiate of Potash. 215 



two ways. Either it must combine with the elements of the salt, 

 or it must decompose the water, imparting to these elements an 

 atom of oxygen, and combining itself with the hydrogen to form 

 muriatic acid. But of the presence of this acid there is no trace, 

 nor does the analysis take account of the addition of oxygen ; for 

 it does not allow the presence of a single atom in the salt. The 

 chlorine, therefore, cannot have acted by decomposing the water ; 

 it must consequently have combined with the elements of the 

 salt. 



This conclusion, which is fairly deducible from the pheno- 

 mena attending the preparation of the salt, is confirmed by ex- 

 periments, both analytic and synthetic, which I proceed to state. 

 . v/fM*. tr i J~ ; ^ fitfi'd i)i]i. .vVv-tMM 



1 . The dry crystals reduced to powder, and treated with con- 

 centrated sulphuric acid, give off chlorine gas. This is abun- 

 dantly perceptible by the smell, though I have not hitherto been 

 able by this means to obtain satisfactory results as to the quan- 

 tity of chlorine present. 

 1m 'ili'^l fcltfJ'Vto iioJi'i. :'_;:.<'.> ; /U vu:. t u> i'{oa woJfov Jjgh 



2. When the same powder, which is of a bright yellow colour, 

 is heated in a glass tube or small retort by means of a spirit-lamp, 

 it is changed into a dark brown colour, giving off during this 

 change a gaseous product, soluble in water, and having the cha- 

 racter of the chloro-cyanic acid, accompanied sometimes by a 

 small quantity of cyanogen. 



3. By GMELIN'S analysis, the salt is anhydrous ; and accord- 

 ingly, when heated to 300 on the sand-bath, it loses nothing, 

 nor, when exposed to a red heat in a tube, does it give off any 

 moisture or trace of ammonia, if the crystals employed have been 

 perfectly dry. We have ascertained two points of difference, 

 then, between this salt and the common prussiate of potash, that 

 it contains chlorine, and is destitute of water. 



