268 Contributions towards [Oct. 



edges are frequently truncated. Sometimes the truncature is so 

 great as to change the crystals into six-sided tables. They are 

 set upon one another. 



They have a rose-red colour, are perfectly transparent, and 

 have a caustic taste, which leaves a saltish impression upon the 

 tongue. 



They speedily deliquesce in the air. They may be very well 

 preserved in a close vessel at the temperature of 77°; but when 

 the temperature is a little higher they lose their transparency, 

 and become covered over with a white powder, owing to the loss 

 of a part of their water of crystallization; yet they do not fall 

 completely to powder. "When strongly heated in a retort they 

 melt immediately, and lose their water of crystallization; and 

 in a red heat they are in a great measure decomposed, the acid 

 passes over into the receiver, and there remains in the retort a 

 black shining crytalline mass, which still contains some acid. 



Not only water, but alcohol also dissolves more than its own 

 weight of this salt. The alcoholic solution burns, when in con- 

 tact with a combustible substance, with a lively red flame, and 

 emits frequent sparks. When the alcoholic solution is slowly 

 evaporated the salt crystallizes in very fine, thin, transparent 

 tables, and sometimes, when the evaporation is rapid, in very 

 fine flat needles. 



The specific gravity of the crystals is 1'560, that of water 

 being 1*000. 



In other respects the solution of these crystals exhibits the 

 properties of the solution of sulphate of manganese. 



Sulphuric acid does not decompose the solution of muriate of 



manganese. 



Estimate of the Proportions of the Constituents. 



A hundred grains of dry crystallized muriate of manganese 

 were dissolved in water, and mixed with a solution of nitrate of 

 silver as long as any precipitate fell. This precipitate being 

 separated by the filter, washed and dried, and heated to the 

 point of fusion in a silver vessel, weighed 130 grains. Now it 

 follows from Klaproth's experiments that 133 grains of such a 

 horn silver contain 20-i- grains of muriatic acid. Hence the 

 proportion of acid in 130 grains may be estimated at 20^- 

 grains. 



After the separation of the excess of silver I precipitated the 

 whole of the manganese by means of carbonate of ammonia, 

 warmed the solution a little, and carefully dried the precipitate. 

 It weighed 69 grains, which is equivalent to 38-j- grains of prot- 

 oxide of manganese. 



As the loss in the 100 grains of muriate of manganese 



