HISTORY OF PRUSSIATES. g^ 



Examination of the lixivia. 



By distillation these constantly give prussic acid and Lixivia exami- 

 ammonia, the origin of which we have seen above. ned * 



They nlso contain carbonate of potash in large quantity ; 

 simple prussiate of notash ; triple prussiate of potash ; sul- ' 



phate of potash ; phosphate of lime; and sulphur. 



They let fall the phosphate of lime as they are evaporated; 

 bow it was sustamed in them I know not. 



If a portion of the lixivium be saturated with sulphate of 

 iron, and the liquor with which the blue produced is brip-bt- 

 ened be examined, phosphate of iron will be discovered in 

 it. It was this phosphate, that led .Westrumb to suppose the 

 acid of prussian blue to be the phosphoric. 



Alcohol applied to the concentrated lixivia takes from 

 them some simple pru :;siate ; but it appeased to me difficult, 

 to exhaust them of it by its means. The triple prussiate 

 remains in the lixivium with the carbonate. 



Of these two prussiates one only can produce prussian 

 blue with the red oxide of iron, which is the triple prussiate, 

 and this because it contains black oxide of iron. The sim- Common suk 

 pie cannot, because it is destitute of this black oxide : but pliate °f iron 



,,. ., . , . more advan- 



II acquires this property, and is converted into triple prus- tageous for 



siate, as soon as the lixivium is mingled with the sulphate makin S P r " s - 



c • r-^ii i i • r. ,, sian blue than 



ot iron ot the snops ; and consequently, if a sulphate com- the red sul- 



pletely red be employed, we shall have much less prussian P hate - 

 blue, because, the black-oxide failing, it cannot form a tri- 

 ple prussiate and afford blue with the same sulphate. Two 

 experiments will render this evident. 



I divided a lixivium into two equal parts. One was pre- Experiment. 

 cipitated with red sulphate, the other with the green sul- 

 phate, of the shops. The surplus oxides being separated by 

 the brightening liquor, the blue from the second was found 

 to be to that from the first in bulk as four to one. 



The first lixivium, when filtered, had a strong kernel smell. 

 I saturated it with potash, to fix the free prussic acid afresh ; 

 and on trying it afterward with the red sulphate, it did not af- 

 ford an atom of blue, but with the green it yielded a °-rear. 

 deal. Hence we may conclude, that a carbonaceous lixivium 

 Cannot yield all the blue it is capable of producing with the 



solution 



