62 PROCEEDINGS OF THE AMERICAN ACADEMY. 



purest alcohol. These and the subsequent operations were conducted 

 in platinum vessels. A portion of the salt thus formed (I. a) was used 

 for Analyses 22, 25, 31, and 32. The remainder of the crystalline 

 powder was washed four times with pure alcohol on the filter pump, 

 dried, ignited, and fused in a large platinum crucible. The trans- 

 lucent cake of anhydrous baric chloride was dissolved in the purest 

 water, and the solution was allowed to stand until it had become 

 neutral. After having been filtered from the baric carbonate, which 

 was of a faintly brownish tinge because of the presence of impurity 

 taken from the platinum during the fusion, the baric chloride was 

 precipitated twice more by means of alcohol. The last crystals were 

 dissolved in the purest boiling water, recrystallized by cooling, and 

 finally washed once with cold water. The very pure salt thus formed 

 was used for Analyses 20, 21, 33, and 35 (Sample I.c). The last 

 mother liquor was freed from most of its salt by the addition of pure 

 alcohol ; and the very small amount of salt remaining in solution was 

 recovered by the evaporation of the large volume of alcoholic solu- 

 tion and analyzed (Sample Lb, Analysis 34). 



The second chief specimen of baric chloride was treated in a 

 different way. A large quantity of the commercially pure salt 

 (" purissimum ") was dissolved in water, and was then evaporated 

 nearly to dryness with excess of pure hydrochloric acid on a steam 

 bath, to decompose the thiosulphuric acid which is usually present. 

 The hot dilute solution of the residue was treated with an excess of 

 hydrogen sulphide, and the whole allowed to stand in the dark for a 

 long time in a tightly corked stout flask. The clear supernatant 

 liquid was siphoned off from the trace of precipitate and made alka- 

 line with baric hydroxide which had been recrystallized six times.* 

 After a suitable time the clear liquid was again decanted and filtered 

 from the sulphides insoluble in the alkaline solution, and all the 

 sulphur from the filtrate was expelled by boiling with hydrochloric 

 acid. The resulting solution was of course free from the heavy 

 metals, but it contained marked traces of calcium, strontium, sodium, 

 potassium, and possibly magnesium. After two successive crystalli- 

 zations from water the salt was still found to contain very small 

 amounts of these metals, but after two precipitations by alcohol the 

 spectroscope was unable to show any impurity in it except a trace of 

 the ever present sodium, upon very careful testing. The two hundred 

 grams of pure salt thus obtained were then ignited in small portions 



* See these Proceedings, XXVIII. 19. 



