1824.] On the Oxidum Manganoso-Manganicum. 267 



already stated that a solution of persulphate or perrauriate of 

 uranium does not crystallize ; but if a portion of sulphate or 

 muriate of potash be added to the solution, we obtain by evapo- 

 ration a uranium salt in combination with the alkaline salt. 



Potash-persulphate of uranium forms a granular crystallized 

 mass, of a very fine lemon-yellow colour. The salt dissolves 

 pretty easily in water. By alcohol it is decomposed in such a 

 way that the persulphate of uranium is dissolved, and the alkaline 

 salt remains behind undissolved. When heated, it loses its 

 water, melts at a low red heat, and begins in this temperature to 

 undergo decomposition ; for it acquires a green colour ; but the 

 decomposition is very inconsiderable, for even after being com- 

 pletely fused, it dissolves again in water with a lemon-yeliow 

 colour. Before it begins to melt it is not altered in the least. 

 The constituents of this salt in an anhydrous state have been 

 given above. 



Ammonia-persulphate of uranium crystallizes like the preced- 

 ing salt. It is easily soluble in water, and in a higher tempera- 

 ture it is decomposed, leaving protoxide of uranium. 



Potash-permuriate of uranium crystallizes likewise, if we add 

 a considerable proportion of muriate of potash to the solution of 

 peroxide of uranium in muriatic acid ; but unless this be done, 

 the double salt crystallizes very slowly. It forms small crystals, 

 sometimes in prisms, sometimes in grains. They are transparent 

 and yellow, and have a regular form ; but are mechanically mixed 

 with muriate of potash ; from which however they may be picked 

 out quite pure ; but the process is very tedious, as the crystals 

 are small. The mixed muriate of potash cannot be separated by 

 crystallizing again, for as it is just as soluble in water as the double 

 salt, they both crystallize at the same time. When heated, the 

 double salt gives out water without being decomposed. It melts 

 when it begins to be red-hot, giving out chlorine gae. It 

 becomes green, and is decomposed, though only partially. 



I have not examined any other double salts, though it is likely 

 that more of them might be easily obtained. 



Article V. 



Examination of the Oxidum Mauganoso- Manganicum, a hitherto 

 unknown Chemical Compound of the Protoxide and Deutoxide 

 of Manganese. By Aug. Arfwedson.* 



In consequence of the experiments which have been made 

 upon the oxides of manganese, it has been concluded that the 



• Translated from the Athandlingar i Fysik, Kcmi, &c. vi, 222. 



