56 H. L. Wells and S. L. Penfield — Gerhardtite, etc. 



selmann states that blackening took place in both, instances 

 when he made the compound, so that he was unable to make 

 it pure and unaltered. The product was composed of minute 

 crystals, forming a powder of a light green color. Specific 

 gravity 3-371. The following chemical analysis proves its 

 identity with the basic nitrate made by other methods. 



Of the substance, dried over sulphuric acid, 1-0631 gram yielded 

 •1229 H„0, -7035 CuO, and 52-4 cc. dry N at 18-9° and 764 mm. 

 (corrected). 



Calculated for Calculated for 



Found. 4CuO . N 2 5 . 3H 2 0. Casselmann's formula. 



H„0 11-46 1126 12-89 



CuO 66-17 66-22 64-99 



NO 22-42 22-52 22'12 



100-05 100-00 100-00 



A basic cupric nitrate mixed with metalic silver was made 

 by H. Eose* by acting on cuprous oxide with silver nitrate 

 solution. Eose not having determined the composition of the 

 salt, Eammelsbergf attempted to do so and assigned to it a 

 composition represented by the formula Cu 10 N 6 O 25 . This dif- 

 fers so widely from the basic salt made by all other known 

 methods that it was deemed advisable to reexamine it. 



Pure cuprous oxide was made by adding a dilute solution 

 of pure glucose to an excess of Fehling's solution heated just to 

 boiling. The precipitate was thoroughly washed, then treated 

 while still wet with a large excess of silver nitrate solution, the 

 liquid was boiled and the whole allowed to digest on a water- 

 bath for several hours. The resulting dark gray voluminous 

 powder was carefully washed with water and dried at 100°. 

 In some preliminary experiments it was found difficult to com- 

 pletely decompose cuprous oxide after it had been dried, and 

 it was also found that the reaction took place only very slowly 

 in the cold ; consequently the above mentioned method for 

 making the mixture was adopted. 



Supposing the mixture to consist of a basic cupric nitrate of 

 Gerhardt's composition and metallic silver, the reaction would 

 evidently be as follows : 



3Cu 2 + 6AgN0 3 +3H 2 = 4CuO.N 2 6 .3H 2 0+6Ag-}-2CuN 2 6 . 



Analysis proved this to be the case. v 



Of the substance dried at 100°, 



I. 1*4958 grams yielded by ignition 1*2848 Ag and CuO, — the lat- 

 ter yielded 1-1459 AgCl. 

 II. 1-9329 grams yielded 1-6592 Ag and CuO, 1-4791 AgCl, -0893 

 H 2 0, and 40-55 cc. dry N at 18-2° and 758 mm. (cor.) 



* Pogg. Ann., ci, 513. f Ber. Deutsch. Chem. Ges., 1877, 1780. 



