332 Cyanide of Potassium from Hot-blast Furnaces. 



rately precipitated by nitrate of silver, the experiment in each 

 case bein^ conducted in a like manner. The chloride of silver 

 from the mixed chlorides, was to the chloride of silver from 

 the chloride of potassium, in the proportion of not more than 

 1004 to 1000. This corresponds to about 15 of sodium salt 

 in 1000 of the mixture. 



That the salt under examination contained no ferro-prus- 

 siate of potash, was proved hy first supersaturating a watery so- 

 lution of it with pure muriatic acid, and then adding a solution 

 of a protosalt of iron. No blue appeared. That the salt did 

 contain cyanide of potassium, was proved hy first adding, to 

 a watery solution of it, a solution of protosulphate of iron, 

 and then redissolving the precipitate by pure muriatic acid ; 

 upon which prussian blue appeared. 



For want of attending to the order in which these reagents 

 should be used, an eminent chemist, expressly seeking for the 

 production of an alkaline cyanide, has merely proved the 

 absence of a ferro-prussiate, where he conceives he proved 

 the absence of an alkaline cyanide. — (Ann. de Chim, et de 

 Phys. tom. lix. pp. 26^', 269.) 



To ascertain the proportion of cyanide of potassium, the 

 method was adopted — which repeated experience has taught 

 me to regard as the best — of estimating that cyanide from 

 what peroxide of mercury it can render soluble. All the pre- 

 caution required is, that the peroxide be pure and in fine 

 powder. Accordingly, 12 grains of the salt were dissolved in 

 about 1000 grains of water, and treated with peroxide. Were 

 those 12 grains entirely cyanide of potassium, they would dis- 

 solve 20 grains of the peroxide of mercury. In point of fact, 

 they dissolved, in three experiments, as under: 



10*77 grains, corresponding to cyanide of ) _,, g . , 

 potassium J 



10-77 53-8 



10 5 52-5 



Cyanide of potassium S^*^ in 100 



Having found, by preliminary experiments, that a given 

 weight of carbonate of potash precipitated from a solution of 

 chloride of calcium the same weight of carbonate of lime, 

 whether pure cyanide of [)otassium was added to it or not, I 

 resolved to estimate the carbonate of potash by that method. 

 50 grains of the salt gave, of carbonate o^ lime, in two experi- 

 ments; 

 16*5 grains, corresponding to carbonate of potash 45*3 in 100 



16-9 46-3 



Carbonate of potash 45*8 in 100 



