1. Graham states that when nitric acid of specific gravity greater than 1·4 acts on copper oxide a basic nitrate is obtained. We were unable to obtain a basic salt under these conditions.

2. Copper oxide and approximately 100 per cent. nitric acid yield copper nitrate trihydrate, nitrogen peroxide, and oxygen. The equation for the reaction is probably CuO + 6HNO3 = Cu(NO3)2, 3H2O + 4NO2 + O2.

3. The only basic nitrate of copper appears to be Cu(NO3)2·3Cu(OH)2. The product obtained by heating the trihydrate to 100° has this composition, and is not Cu(NO3)2·2Cu(OH)2, as stated by Graham.

4. Dehydration of copper nitrate does not yield anhydrous copper nitrate, but results in decomposition, with formation of basic copper nitrate, whether the dehydration is performed at ordinary or higher temperatures.

5. Copper oxide does not interact with nitric anhydride.

6. The only hydrates of copper nitrate appear to be the trihydrate and hexahydrate. The transition temperature is 24·65° (±0·05) corr.

7. Concentrated nitric acid dehydrates the hexahydrate, while dilute nitric acid hydrates the trihydrate. It was not found possible to determine the concentration of nitric acid, which would be in equilibrium with both hydrates.