406 PROCEEDINGS OF THE AMERICAN ACADEMY. 



(6) 1 gram CuO, heated 1 hour at 830° ±, * gave 0.68 c.c. gas. 



(7) " " " " 0.69 



(8) " " " " 0.68 



Average 0.68 c.c. gas. 



(9) 1 gram CuO, heated ^ hour at 870^ ±, t gave 0.55 c.c. gas. 



(10) 1 gram CuO, heated i hour at 900° ±, J gave 0.08 



(11) 1 gram CuO, heated | hour at 950° ±, § gave 0.05 c.c. gas. 



(12) " " " " 0.04 



Average 0.05 c c. gas. 



(13) 1 gram CuO, lieated i hour at 1100° ±, || gave 0.01 (?) c.c. gas. 



Second Series : Second Preparation of Gvpric Oxide. 



(14) 1 gram CuO, heated 4 hours at 280° i.T gave 0.04 c.c. gas. 



(15) 1 gram CuO, heated 1 hour at 290° ±,^ gave 0.12 c.c. gas. 



(16) 1 gram CuO, heated 5 hours at 630°,** gave 0.54 c.c. gas, 



(17) 1 gram CuO, heated 3 hours at 830°,tt gave 0.57 c.c. gas. 



(18) " " " " 0.59 



(19) 1 gram CuO, heated 5 hours at 830°, gave 0-57 



Average 0.58 c.c. gas. 



(20) 1 gram CuO, heated 20 minutes at 870° ±,tt gave 0.42 c.c. gas. 



(21) " 150 " " 0.23 " 



(22) " " " " 0.14 " 



(23) 1 gram CuO, heated 2 hours at 950°±,tt gave 04 c.c. gas. 



(24) 

 (25) 



0.07 

 0.04 



Average 0.05 c.c. gas. 



These two series of experiments, qualitatively and quantitatively 

 similar to those carried out in 1891, lead to the following conclusions, 

 which are copied verbatim from the paper on the atomic weight of 



copper : — 



* Sodic chloride easily fused; strontic chloride just fused; sodic sulphate re- 

 mained solid. 



t Sodic sulphate just fused. 



X Sodic sulphate easily fused ; higher than last. 



§ Baric chloride easily fused ; potassic sulphate remained solid. 



II Potassic sulphate fused, as well as the cupric oxide itself. 



If Mercury thermometer. 



** Thallous sulphate just melted. 



tt See foot-notes to preceding series for criteria regarding temperatures 830°, 

 870°, and 950°. 



