Mk. Ti:.nm:nt on (he Yellow PrmtiaU of Ptfaal i 

 I'nMl quantity of Ag CI, 116-66 



29-30 KO C0 2 = 60-27 Ag CI. 



10-93 KO HO =27 48 Ag CI. 



1-58 KC1 = 3-00 Ag CI. 



90-75 



Leaving 2491 AgCl = 11-42 KCy. 



A second experiment gave 11-72 K Cy. 



A third experiment gave 10-95 KCy. 



To determine whether the precipitate of cyanide of silver contained 

 any ferrocyanide, after being ignited and weighed, it was digested in 

 nitric acid, and tested by the following reagents : — yellow prussiate, 

 hydrosulphuret of ammonia, caustic ammonia, and caustic soda, which 

 gave none of the reactions characteristic of iron ; thus proving the absence 

 of all trace of iron. If there had been any ferrocyanide present, those 

 tests could not have failed in detecting the iron. This is in accordance 

 with Liebig's views, who states that the fused mass does not contain a 

 trace of ferrocyanide, but it contains a large quantity of metallic iron, as 

 well as sulphuret of iron, by the action of the sulphuret of potassium 

 (which is derived from the sulphate in the potash,) on the oxide of iron 

 of the blood, when dried blood is used, or that formed from the vessels. 

 If the mass be treated with cold water, and the filtered solution evapo- 

 rated, no ferrocyanide is obtained ; but if, while covered with water, it is 

 gently heated for some hours, iron is dissolved, and a yellow solution is 

 obtained, which is rich in ferrocyanide of potassium. These results are 

 opposed to those of Runge, who affirms (Poggendorff's Annalen, LXVI. 

 95,) that if the black cake is washed with spirit (he does not state the 

 strength,) till nothing more is taken up, the black residue, when treated 

 with cold water, gives yellow prussiate. 



II. Analysis of Insoluble Matter. 



1. Estimation of Volatile Matter. — The black mass, from 50 grs., after 

 being ignited, lost 9 = 18 per cent, of volatile matter. 



2. Estimation of Sulphate of Lime. — The residue was then washed 

 with water, until the liquid passing through ceased to give a precipitate 

 of Ba CI, when it lest in weight 4*76 = 9'52, to which add 1*9 obtained 

 in former experiment, and we have 11-42 CaS0 3 . 



The insoluble portion was fused with NaO C0 2 , the fused mass was 

 then treated with HC1, and evaporated to dryness ; HC1 was again added 

 to the dry silica, and after standing for some time, water was added ; it 

 was then filtered, washed, dried, ignited, and weighed, when it gave 1-65, 

 or 3*3 per cent. 



3. Estimation of Iron. — The solution filtered from the silica was 

 treated with caustic ammonia, which gave a bulky brown precipitate con- 



