1911-12.] Preparation and Properties of Basic Copper Nitrate. 7 
as to the formation of oxygen in the reaction. With this concentrated nitric 
acid the interaction with copper oxide was very sluggish, and only a small 
fraction of the copper oxide was attacked in the course of half an hour. 
The general conclusion from our experiment is that copper oxide interacts 
with anhydrous nitric acid at a temperature of 70° to 75°, according to the 
equation 
CuO + 6HN0 3 = Cu(N0 3 ) 2 , 3H 2 0 + 4N0 2 + 0 2 . 
Dehydration of Copper Nitrate Hexahydrate. — Copper nitrate hexa- 
hydrate may be readily dehydrated in a vacuum desiccator by phosphorus 
pentoxide or solid potash. After a day or two the residue consists of copper 
nitrate trihydrate, which is comparatively stable, but does undergo very 
slow further decomposition. When the hexahydrate is desiccated nothing 
but water is lost until the trihydrate stage is reached. This was proved by 
passing a stream of air through a tube packed with the hexahydrate. The 
air was first purified by passing successively through caustic soda, sulphuric 
acid, and phosphorus pentoxide. The air then passed slowly through the 
tube of hexahydrate, and finally through some catfstic soda solution. After 
several hours the caustic soda was warmed with zinc-aluminium alloy, and 
the gas evolved tested for ammonia. Complete absence of ammonia proved 
that no nitrogen compound had been given off during the dehydration of 
the hexahydrate. 
Dehydration of Copper Nitrate Trihydrate. — Graham states that when the 
trihydrate was kept at 60° for some time, it slowly decomposed with forma- 
tion of a basic salt, Cu(N0 3 ) 2 * 2Cu(OH). 2 , and that at higher temperatures the 
same decomposition occurred more quickly. A basic salt, Cu(N 0 3 ) 2 * 3Cu(OH ) 2 , 
has been prepared by many investigators (see Dammers Handbuch II., 2, 
716), but the basic salt mentioned by Graham does not appear to have been 
made in any other way. Graham’s experiment was therefore repeated. 
Some copper nitrate trihydrate was kept at 100° until decomposition was 
complete, and the residue analysed without further treatment. 
0*0910 grms. yielded on ignition 0*0605 grms. of copper oxide. 
Cu = 52*9 per cent. 
0*1320 grms. gave by Crum’s nitrometer method 12*0 c.c. of nitric oxide 
at 761 mm. and 17°. 
N = 5*39 per cent. 
Calculated for Cu(N0 3 ) 2 * 2Cu(OH) 2 , 
Cu = 49*6 per cent., h T = 7*36 per cent. 
Cu(N0 3 ) 2 * 3Cu(OH) 2 , 
Cu = 53*0 per cent., N = 5*85 per cent. 
