H. L. Wells and S. L. Penfield — Gerhardtite, etc. 55 



HO. 



1. 

 11-23 



Found. 



II. 

 11-57 

 66-22 

 22-10 



Calculated for 



4CuO.N 2 6 .3H 2 0. 



11-26 



2 



CuO 



N 2 5 



66-29 



22-48* 



66-22 



22-52 



100-00 99-89 100-00 



Artificial Basic Cupric Nitrate made by other methods. 



Grahamf investigated a compound made by heating normal 

 cupric nitrate. His formula was incorrect, owing to the fact 

 that he merely determined cupric oxide and volatile matter, 

 and, consequently, had insufficient data for determining it. 



Gerhardt;}: showed the true composition of Graham's com- 

 pound to be 4CuO. N 2 5 . 3H 3 0. He made it a number of 

 times under varying conditions and always obtained analytical 

 results corresponding to this formula. He also showed that the 

 precipitate formed by adding ammonium hydroxide not in ex* 

 cess to a solution of the normal nitrate has the same composi- 

 tion. 



The following investigators have since confirmed Gerhardt's 

 results : Gladstone§ by analysis of the compound made by heat- 

 ing the normal nitrate ; Kiihn| by examination of the precipi- 

 tate formed by ammonium hydroxide; Yogel and Keischauer^f 

 by investigation of the light, iridescent, blue-green, crystalline 

 scales made by boiling mixtures of the solutions of cupric ni- 

 trate and potassium nitrite and also by boiling the deep green 

 solution made by passing nitrous acid gas through water con- 

 taining cupric hydroxide in suspension ; Field,** and Eeindelf f 

 by examining the precipitate formed by the addition of potas- 

 sium hydroxide, not in excess, to solutions of normal cupric 

 nitrate. 



On the other hand, Casselmann^ has described a basic nitrate 

 which is precipitated by boiling solutions of cupric nitrate with 

 acetates and various other soluble salts of organic acids and to 

 which he ascribes a composition corresponding to the formula 

 2(4CuO.N 3 5 )7H 3 0. It will be noticed that this differs 

 from Gerhardt's formula by only iH 3 ; hence we thought it 

 proper to reinvestigate the compound. 



Sodium acetate was added to a hot, dilute solution of cupric 

 nitrate until a copious precipitate was formed. The liquid was 

 boiled until the precipitate became dense when the latter was 

 thoroughly washed with cold water. No discoloration of the 

 product was noticed either on boiling or washing, although Cas- 



* By difference. || Jahresber., 1, Engl, transl., p. 340. 



f Phil. Trans.. 1837, 57. j( Jahresber., 1859, 216. 



i Jour. Pr. Chem., xxxix. 136. ** Idem. 1862, 216. 

 § Idem, xliv, 184. f+ Idem,' 1867, 304. 



X\ Zeitschr. Anal. Chem., 1865, 24. 



