328 PROCEEDINGS OP THE AMERICAN ACADEMY. 



cobalt ; and feeling that the " Gnomium " question raised by Kriiss and 

 Schmidt had never been conclusively laid at rest, v/e naturally dwelt espe- 

 cially upon it. Unfortunately, one cannot enter into a discussion of this 

 subject without directly antagonizing many views which have been ex- 

 pressed on one side or the other ; but of course the following results are 

 recorded solely in the interests of truth, without controversial bias. 



The balance and weights used in the work described were the same as 

 those described in the former paper. The weights were re-standardized, 

 with results very similar to those found a year before. All weighings of 

 nickelous bromide were reduced to the vacuum standard by the addition 

 of 0.114 milligrams per gram to the observed weight. The specific 

 gravity of nickel (about 8.7) is so near the specific gravity of brass (8.4) 

 that the correction of the nickel to the vacuum standard is less than one 

 part in a hundred thousand, hence it may be omitted. 



Experiments concerning the Purity of the Materials. 



The purification of our nickelous material has already been described 

 at length.* Most of the work described below was done with nickel 

 which had been purified by Mond's process and many subsequent opera- 

 tions (Sample Ill.t), but two analyses were made with a somewhat less 

 pure sample (No. II. t) made from commercial material. Since we had 

 proved that further protracted treatment produced no effect on the com- 

 bining weight, evidently these specimens were quite pure enough for 

 our purpose. 



Kriiss and Schmidt used glassware in their preparation work, there- 

 fore it seemed worth while to make an exact observation of the well 

 known danger involved in this practice. To this end two very carefully 

 treated specimens of spongy nickel were prepared, one having been made 

 wholly in platinum, and the other wholly in the best Bohemian glass, 

 which had been thoroughly steamed. The former of these preparations, 

 which was supposed to be absolutely pure, left upon sublimation as bro- 

 mide in a stream of bromine vapor only a very minute siliceous residue. 

 The specimen of nickel which had been prepared in glass vessels was 

 totally different in appearance from the one prepared in platinum ; in- 

 stead of being metallic and coherent, it was black and powdery. Upon 

 the conversion of about ten grams of this dark powder into nickelous 

 bromide, a beautifully iridescent voluminous residue, weighing about five 

 milligrams and consisting mainly of silica, was left in the boat. Evi- 



* These Proceedings, XXXIII 102. t Ibid , 105. 



