HAVING reason to think that silver nitrate might interact with nitric oxide if heated in it, and there being no information obtainable on this point, I have made some experiments on the action of nitric oxide on silver nitrate, as well as on other nitrates, I n the first place, something had to be ascertained as to the behaviour of silver nitrate when heated alone, Heated for 15 minutes in dry air or carbon dioxide, it suffers no chemical change until the temperature is close to the melting

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... t of sulphur (444'), and the slight decomposition which occurs at that temperature, being accompanied by an action on the glass, may be due to that action. A minute quantity of oxygen seems to be liberated, and there is a very slight greying of the faintly yellow liquid ; on cooling and dissolving, there is slight turbidity from the presence of silver, and a trace of nitrite can be detected. Only at a much higher temperature does the salt decompose with free effervescence, and then nitric peroxide accompanies the oxygen, and silver is deposited j even then, nitrite is present in the mass only in very small quantity at any time, there never being enough to remain undissolved when the nitrate is treated with a little water. This is sufficient, howewr, to show that the primary decomposition of silver nitrate by heat alone is into silver nitrite and oxygen, the instability of silver nitrite a t much lower temperatures, although diminished by the presence of nitrate (Trans., 1871, 24, 85), accounting fully for its being found in such small quantity when the temperature is high, and for the production of nitric peroxide and silver instead. As determined by Carnelley, the melting point of silver nitrate is 2 1 7 ' . The nitric oxide used for the experiments was prepared by the ferrous sulphate method, stored for 2 days in a glass gas-holder, and dried in its passage to the silver nitrate by a sulphuric acid column, At starting, the air in the drying apparatus and in the tube containing ( 3 2