58 PROCEEDINGS OF THE AMERICAN ACADEMY. 



increasing heat, specimens of very pure material were heated at many 

 different temperatures by means of a Berzelius spirit lamp, and finally 

 raised to redness. The residues were then dissolved in water and the 

 alkalimetric corrections were determined and applied in the manner 

 which has just been described. Below are given the experimental 

 data. 



(1.) 3.17+ grams of pure baric chloride which had been dried to con- 

 stant weight (for twelve hours) at 260°+ lost 0.27 milligram on heating 

 to somewhat over 300°, 0.18 milligram more on heating to about 450°, 

 and yet 0.30 milligram upon ignition at a medium red heat. To neutralize 

 the baric hydroxide found upon dissolving the salt, about 0.4 cubic centi- 

 meter of the standard solution of hydrochloric acid was required. Since 

 a cubic centimeter of this solution corresponded to a milligram of silver, 

 it is evident that the correction to be added to the weight of baric 

 chloride amounted to 0.09 milligram. 



(2.) About 3 grams of baric chloride dried at 400° lost no weight on 

 heating to redness. The alkalimetric correction was +0.12 milligram. 



(3.) About 5.0 grams of baric chloride dried at 400° lost 0.17 milli- 

 gram on heating to dull redness. The alkalimetric correction to be added 

 to the weight of the baric chloride amounted to 0.12 milligram. 



(4.) 5.46 grams of baric chloride dried at 250° lost 0.66 milligram on 

 heating to dull redness, 0.22 milligram of this loss being accounted for by 

 the alkalimetric correction. 



(5.) A repetition of Experiment 4 showed a loss of 2.0 milligrams 

 between 250° and dull redness, only 0.10 milligram of this amount cor- 

 responding to the alkaline earth found. 



(6.) About 4.0 grams lost 1.20 milligrams between 300° and dull red- 

 ness, the alkalimetric correction being only 0.06 milligram. 



(7.) 2.61 grams of baric chloride dried at 300° lost 0.40 milligram 

 upon being ignited to a bright red heat in a stream of nitrogen. 0.15 

 milligram of this loss was due to substitution of oxygen for chlorine. 



(8.) 6.37 grams of baric chloride which had been dried at 200° lost 

 1.75 milligrams of water upon being heated to 300°±, and 1.30 milli- 

 grams more upon being partly fused at a bright red heat in a stream of 

 nitrogen. The alkalimetric correction was +0.74 milligram.* 



(9.) 3.6 grams of baric chloride dried at 300° lost 0.32 milligram upon 

 being heated to dull redness, only 0.04 milligram being due to loss of 

 chlorine. 



(10.) 3 11 grams of baric chloride which had been prepared by drying 

 large clear crystals at 160° lost 70 milligram on heating to dull redness. 

 The alkalimetric correction was 0.29 milligram. 



(11.) 2.65 grams heated to dull redness lost 0.17 milligram upon 



* See page 77 of this paper. 



