182 Contributions towards [Skpt. 



by carbonate of ammonia,* 2054 grains of carbonate of man- 

 ganese dried at the temperature of £0°. 



From this experiment it follows, that 100 parts of carbonate 

 of manganese consist of 



Metal 4.8-60 



Acid 



Water J> 51 



Oxygen « 



} 



100-00 



(B.) On the protoxide. — Both the pure protoxide and the 

 carbonate of manganese dissolve completely in sulphuric acid, in 

 whatever state of concentration it be. The solution has the same 

 properties as that mentioned in the last paragraph, and what I 

 now say of it may, to save repetition, be applied to both. 



When the neutral solution is rapidly evaporated, the sulphate 

 of manganese separates in the state of a granular powder, or 

 embryo crystals ; and no crystals are obtained during the cooling 

 of the liquid. To obtain this salt in the state of regular crystals 

 the saturated solution must be left to spontaneous evaporation. 

 I gained the same object more speedily by means of some crystals 

 of sulphate of manganese, which I introduced into a solution 

 concentrated, as far as possible, by rapid evaporation. I then 

 placed the solution for farther evaporation upon the top of a 

 stove, where the temperature was between 68° and 73°. By 

 this contrivance I reduced the whole salt, without exception, to 

 a regular state. 



The crystals of sulphate of manganese which first shoot 

 are of a faint rose-red colour. The last crystals have a white 

 colour, and contain a great excess of acid. 



Properties of crystallized Sulphate of Manganese. 



It crystallizes, 1. In very broad flat four-sided prisms, either 

 complete or slightly truncated on the alternate edges of the 

 sides. The crystals are usually more or less intermixed with 

 each other, and hence incomplete. 2. In rhombs. 



The crystals are completely transparent, have a light rose- 

 red colour, and a bitterish metallic taste. 



At the temperature of 55° they remain unaltered in the air, 

 and do not attract more oxygen even when left in contact with 

 oxygen gas. At the same temperature, 2-i parts of water dissolve 

 one part of the salt. They are insoluble in alcohol. 



» I always took tare to convince myself by repeated experiments that no 

 oxide remained in solution in the liquid. — J. 



