88 ATOMIC WEIGHT DETERMINATIONS. 



treme difference 0.08. Ag = 108; CI = 35.5. In three 

 cases the nickel chloride was prepared by dissolving fused 

 nickel in aquia regia, repeated evaporation to dryness with 

 HCl, and heating for from twelve to twenty-four hours in a 

 current of HCl gas. In two cases it was produced by pass- 

 ing a current of chlorine over spongy nickel. The chloride 

 analyzed was crystalline and volatile without residue. 

 {Annal. de Chim. et de Phys., (3,) 65, 1859, 149.) 



E. Schneider : 58.058 (O = 16). 



In consequence of Marignac's criticism (that as nickel 

 oxalate is insoluble it cannot be purified by recrystaltiza- 

 tion) Schneider repeated his former determination, making 

 special tests for oxalic acid, sodium, and chlorine, with the 

 above result. [Poggend. Ann., 107, 1859, 616.) 



W. J. Russell : 58.738 (0 = 16 ). 



Determined from the mean of thirteen experiments on 

 the reduction of the oxide in hydrogen. Extreme differ- 

 ence, 0.12 for O = 16. The oxide was prepared from three 

 specimens of commercial nickel, which were first converted 

 into pure oxalate and then into nitrate. The oxide was 

 obtained by decomposing the nitrate by a very strong heat. 

 {Journ. Chem. Soc, (2,) 1, 1863, 61.) 



Schneider remarks that a portion of the oxide analyzed 

 may have been reduced during the process of decomposing 

 the nitrate. {Poggend. Ann., 130, 1867, 310.) Marignac 

 points out the same danger. (Bibl. Univ., Arch, des Sciences^ 

 (2,) 1, 374.) 



E. VON SoMMARUGA : 58.026 (0 =16). 



Determined from the amount of barium sulphate obtained 

 by precipitating the double sulphate of nickel and potassium 

 with barium chloride. The number is the mean of six 

 experiments; extreme difference, 0.168 for = 8, S = 16 ; 

 Ba [no doubt] = 68.5 ; K = 39.2. The salt was prepared 

 by solution of commercial nickel in sulphuric and nitric 

 acid, adding potassic sulphate to the solution, and repeatedly 

 recrystallizing the double sulphate. [JErdmann's Journ. fiir 

 Prak. Chem.,^100, 1867,115; Sitz.-Ber. der k. k. Akad., 1866.) 



C. Winkler : 59.05 (O = 16). 



Determined by the amount of gold precipitated from a 

 solution of neutral crystallized potassium chloro-aurate by 



