1S6 M. Setterberg's Experiments on the Sulphurcts of Cobalt 



Molybdaaia combines with chlorine in three proportions. 

 The first is red, and a little volatile. The second is black, 

 very fusible, very volatile, and crystallizes in a black mass, 

 of a brilliant colour, like iodine, which it resembles even m 

 the colour of its gas, which, however, is more red than violet. 

 The third is colourless, and crystallizes in scales. These 

 three chlorides correspond to the muriates of the protoxide, of 

 the deutoxide, and of the peroxide, that is to say, of the acid. 

 Iodine does not combine in the dry way with molybdsena, 

 but the hydriodic acid dissolves the protoxide and the deu- 

 toxide. The molybdic acid decomposes it, and separates the 



iodine from it 



The best method of obtaining molybdama, in some quanti- 

 ty, is to heat the molybdic acid in a porcelain tube. When 

 this tube is heated to redness, there is introduced into it a cur- 

 rent of hydrogen gas, which is continued as long as it pro- 

 duces water. 



5. M. Setterberg's Experiments on the Sulphurets of Cobalt. 



M. Setterberg has found that the deutoxide of cobalt decom- 

 poses sulphuretted hydrogen gas when cold. The sulphuret 

 thus produced -contains three atoms of sulphur. Hydro- 

 chloric acid dissolves some of the cobalt in it, and leaves an- 

 other sulphuret of cobalt in the form of a black powder, which 

 contains/our atoms of sulphur for one atom of metal. 



6. M. Mosander on. the Precipitation of Magnesia by Carbo- 



nate of Soda. 



During the analysis of a new species of noble serpentine, 

 M. Mosander made an observation which merits the atten- 

 tion of chemists who are occupied with the analysis of mine- 

 rals. He remarked, that when the carbonate of soda is used 

 to precipitate magnesia, the precipitate contains a double carbo- 

 nate of soda and magnesia; that the alkali cannot be removed 

 from it by edulcoration with water, and that the washings al- 

 ways contain magnesia. It is necessary, therefore, to evapo- 

 rate the alkaline liquid to dryness, and melt the salt to render 



