102 



Triple prussiate 

 of manganese, 



and of copper. 



Perhaps other 

 prussian pig- 

 ments. 



Simple prus- 

 siates of other 

 metals. 



HISTORY OP rilUSSlATES. 



there can be no objection I imagine to the theory that 

 asserts, that the white or blue prussiates are triple com- 

 bination*, as well as the prussiate of potash, which has 

 concurred to form them. 



Prussiate of manganese being put into a solution of pot- 

 ash, the result was the crystallizable triple prussiate of 

 potash, of a yellow colour, and containing its due propor- 

 tion of black oxide. This prussiate of manganese then is 

 a triple combination, containing the black oxide. The 

 prussiate of copper of a sanguineous colour is no doubt 

 another, for the simple prussiate of copper is yellow. 



Scheele informs us, that other oxides also have the pro- 

 perty of converting the simple prussiate of potash into a 

 triple salt. This apparently opens a field to a series of re- 

 searches, which are the more interesting, as they may lead 

 to the discovery of some colour equally valuable with prus- 

 sian blue ; and lastly we may conclude, from all that has 

 been said, that no simple prussiate of iron exists; a kind 

 of combination however, of which other metals are sus- 

 ceptible, as will soon appear. 



Destructive 

 distillation of 

 Prussian blue. 



Distillation of Prussian Blue. 



This prussiate is destroyed by exposure to a high tempe- 

 rature. The new products, that arise from it, confirm the 

 theory Bcrthollet has given us respecting the nature of the 

 prussicacid. We obtain an acid which escapes destruction, 

 carbonate of ammonia, a little free carbonic acid, gaseous 

 oxide in abundance. An ounce of good blue of the shops 

 afforded rather more than five pints of this gas, with as 

 much carbonic acid as made up the whole three quarts. 

 The water of the trough contained prussic acid fixed by 

 ammonia. This prussiate, as is well known, follows the 

 steps of that of simple potash ; it cannot produce blue 

 with solutions of red oxide, but it does with those of 

 oxklcs at a minimum, because at the same time it forms it- 

 self into a triple or tingeing prussiate. 



The residuum weighed five drachms fifty-two grains. 



It was perfectly black, and very attractable by the magnet, 



A pyropborus. It is a pyrophorus, which takes fire with rapidity. After it 



has beep kept in a phial not closely stopped, so long that it 



will 



