456 Clarice and Schneider — Experiments upon the Silicates. 



almost quantitatively converted into chloride, showing the 

 stability of the latter in a stream of the dry gas. 94*13 per 

 cent of the required chlorine was taken up by the oxide, so 

 that the possible formation of oxychlorides in our experiments 

 may be fairly left out of account. 



Similar experiments with brucite, however, gave apparently 

 anomalous results. The mineral examined was typical ma- 

 terial from Texas, Lancaster County, Pennsylvania, which was 

 first analyzed and subjected to dehydration estimations. The 

 data are as follows : 



MgO 67-97 



FeO undet. 



MnO -97 



Fe„0 3 -39 



H 2 30-81 



100-14 



Water lost at 105° -IS 



" " 250° _• -46 



" " 383°-412°, 2 hours, 7"57 



" " " 3 " more 19-37 



a u a 9 a a .(w> 



" " 498°-527°, 1 " -23 



" " " 1 " more none 



" " full ignition 2-94 



The greater part of the water, therefore, nine-tenths of it y 

 is lost at about 400° C, but is given off somewhat slowly. 



Heated for 28 hours to 383°-412° in dry hydrochloric acid 

 gas, constant weight was not attained ; but at this point the 

 experiment was stopped, and only 10 33 per cent of the mag- 

 nesia had been converted into chloride, or a little less than one- 

 seventh of the total amount. Several other experiments, at 

 temperatures ranging from 200° to 500° gave similar results, 

 all low, and in no case was more than one-fifth of the 

 required chlorine absorbed. At the higher temperature, 498° 

 to 527°, the reaction went farthest, and the absorption of 

 chlorine was still going on at a very slow rate. In this case, 

 the brucite must have become almost dehydrated ; but the 

 oxide so formed was different in its behavior from the precipi- 

 tated oxide previously examined. The difference may have 

 been due to physical causes, such as a different degree of com- 

 pactness in the material ; but it is doubtful whether that sup- 

 position would full} 7 account for the anomaly. Probably 

 magnesium hydroxide, like other hydroxides investigated by 

 Carnelley and Walker,"* undergoes progressive dehydration 

 through a series of stages ; each step being attended by a poly- 



* Jour. Chem. Soc, liii, p. 59, 1888. 



