336 Mr. Graham's Account of the Formation of Alcoates. 



to 25*5 grains. On being gently heated, the deutoxide of 

 azote was evolved, and the chloride restored to its former co- 

 lour. 



The solution of protochloride of iron in absolute alcohol, 

 absorbed a much greater quantity of deutoxide of azote, and 

 became nearly black. A solution saturated with gas began 

 to boil at 100°, evolving gas in great abundance, which, being 

 collected in the pneumatic trough, proved to be pure deutoxide 

 of azote. The greater part of the gas was expelled before the 

 alcohol rose to its boiling point, and after the solution was in 

 the state of ebullition for a few seconds gas ceased to rise, and 

 the alcoholic solution recovered its original colour, which was 

 generally a chocolate-brown, from the presence of a little bi- 

 chloride of iron. The quantity of gas evolved from a solution 

 of one part protochloride of iron in five parts absolute alcohol, 

 amounted to 23 times the volume of the alcohol. 



I think it probable that the absorption of deutoxide of azote 

 by protochloride of iron, is analogous to the absorption of al- 

 coholic and aqueous vapours by the same body. For I find 

 that protochloride of iron absorbs alcohol-vapour as well as 

 the vapour of water. The absorption of deutoxide of azote 

 may depend upon a tendency of chloride of iron to deliquesce 

 in like manner, in an atmosphere of that neutral oxide. At 

 a very low temperature, which it is perhaps out of our power 

 to reach, protochloride of iron would probably absorb this gas 

 in sufficient quantity to exhibit the appearance of delique- 

 scence, "and might form with it a neutral compound similar 

 to its alcoate or hydrate. 



A reason can also be given for the superiority of the aqueous 

 and alcoholic solutions of this chloride over the dry chloride 

 itself, in absorbing deutoxide of azote. We formerly saw that 

 the alcohol of the alcoate of chloride of calcium was completely 

 expelled by a heat of 250°, when no water was present, but 

 that, when a considerable quantity of water was present, al- 

 cohol was retained by that chloride at the temperature of 400° 

 or 500°. Now, chloride of iron might be enabled to retain 

 deutoxide of azote more powerfully, by the assistance of al- 

 cohol or water, in the same manner. But the retaining power 

 we have formerly found in a similar case to be an index of the 

 absorbing power. Hence solutions of protochloride of iron 

 might absorb deutoxide of azote more powerfully than the 

 chloride itself. 



LVII. On 



