150 Dr TURNER'S Chemical Examination 



the atmospheric air was expelled from the tube. As it is diffi- 

 cult by this, as well as by Dr DAVY'S process, to procure a per- 

 fectly pure chloride of manganese, I had recourse to the follow- 

 ing method. A solution of the muriate of manganese was eva- 

 porated to dryness, the heat being carefully regulated so as not 

 to decompose any of the salt, and the dry compound was placed 

 in a spherical cavity in the middle of a barometer tube about six 

 inches long. Muriatic acid gas was then transmitted through 

 the tube, and heat applied by the flame of a spirit-lamp. The 

 chloride entered into perfect fusion at a low red heat, and on 

 cooling yielded a highly crystalline lamellated mass of a beauti- 

 ful pink colour. Every trace of acid and moisture was expelled 

 by heat ; and while the tube was still hot, its extremities were 

 closed by corks, so that the chloride might be weighed without 

 attracting moisture from the air. In the sense above explain- 

 ed it was quite neutral. Of this chloride 12'47 grains were dis- 

 solved in distilled water, and formed a colourless solution with- 

 out any residue. The muriatic acid was thrown down by the 

 nitrate of silver, and yielded 28'42 grains of the fused chloride 

 of silver, equivalent to 7'008 grains of chlorine. Consequently 

 the chloride of manganese consists of 



Manganese .... 5'462 28'06 



Chlorine 7'008 36 



It follows from the preceding researches, that 28 is the true 

 atomic weight of metallic manganese, and 36 the equivalent of 

 that oxide of manganese which forms definite compounds with 

 acids, and which I regard as the real protoxide of the metal. It is 

 consequently composed of 28 parts of manganese and 8 parts of 

 oxygen. These numbers agree with the atomic weight of man- 

 ganese as stated by Dr THOMSON, but not with that given by 

 BERZELIUS, who fixes it at 28*463. This estimate is made from 

 an analysis of M. ARFWEDSON, who finds that the deutoxide of 



