MANGANESE. 371 



lour becomes violet, and then red ; and, finally, 

 black oxide of manganese precipitates, and the 

 liquid loses all colour. In consequence of this 

 curious succession of colours, the liquid thus ob- 

 tained used to be distinguished by the name of 

 mineral chameleon. We may employ saltpetre 

 instead of potash, and the process will succeed 

 equally well. When the liquid had assumed a 

 red colour, Chevillot and Edwards* concentrat- 

 ed it by evaporation, and obtained a red colour- 

 ed salt in needles. This salt is neutral, and is 

 composed of potash, united to an oxide of man- 

 ganese, which possesses acid properties, and 

 which, consequently,, is different from the three 

 oxides, which have been already noticed. 



This red salt has received the name of man- 



of potash. 



ganate of potash. It possesses some singular 

 properties. It crystallizes in four-sided rectan- 

 gular prisms, has the diamond lustre, a purple 

 colour, and a taste at first sweet, and similar to 

 that of walnuts, but which leaves a very disa- 

 greeable impression in the mouth. When these 

 crystals are heated, in contact with hydrogen 

 gas, they set it on fire. They detonate violently 

 with phosphorus, set fire to sulphur, antimony, 

 and arsenic, and rival chlorate of potash itself in 

 their power of supporting combustion. The acid 

 cannot be separated from this salt without de- 



* Ann. de Chhn. et de Phys. VI J I. 337. 

 A a2 



