Mr. Smith on the Hydrates of Nitric Acid, 457 



A quantity of this red acid was introduced into the decolo- 

 rizing apparatus, and a constant rapid stream of dry air made 

 to bubble through it for two hours ; at the expiration of that 

 time it was found to be perfectly limpid, and colourless as 

 water, and to have a specific gravity of 1*516 at 60°. 



50 grs. of the last acid were weighed out and neutralized 

 with pure carbonate of soda as before. The numbers below 

 will show the amount required for saturation : — 

 Exp. Caib. of soda. Mean. 



2* * * 41*69 l^^*^^^ corresponding to 42*27, or 

 «' * * ^1 /.J I 84*54 per cent, nitric acid. 

 3. . . 41*64 J ^ 



This acid began to boil at about 184°, the greater part di- 

 stilling over between the temperatures of 184° and 188°; it 

 afterwards rose when near the end to 200°. 



The first portion that came over was collected apart, intro- 

 duced into the decolorizing apparatus, and dry air again drawn 

 through it until it was quite colourless. This was found to 

 be necessary after each distillation, on account of the decom- 

 position that it suffered upon boiling, which rendered it as 

 dark in colour as the original acid. 50 grs. of the colourless 

 acid, of the specific gravity of 1*517 at 60°, were weighed out, 

 and carbonate of soda very carefully added until neutral to 

 test-paper. The increase in the specific gravity this time only 

 amounted to '001. 



Exp. Carb. of soda. Acid. Mean. 



1. . . 41-79 = 42*361 . 



2. . . 41-81 = 42*38/^"^ '^'* 



Hence in 100 parts — 



According to theory with 1 eq. water. 



Real acid . . 84*74 Real acid . . 85*71 

 Water . . . 15-26 Water . . . 14*28 

 100*00 99*99 



This would give, when compared with the theoretical compo- 

 sition of nitric acid with 1 equiv. of water, a deficiency of "97 

 in the acid, and an excess of '98 in the water. 



This hydrate, when pure, was a perfectly limpid and colour- 

 less liquid, like so much water; it boiled at 184°, and had a 

 specific gravity of 1*517 at 60°. It was found not to have 

 the slightest action on tin or iron even when boiled. A por- 

 tion of this acid placed in a freezing mixture composed of ice 

 and salt suffered no change. 



These experiments leave little doubt concerning the com- 

 position of the first hydrate of nitric acid, namely, that it is 

 the true mono-hydrate, consisting of 1 equiv. of nitric acid 

 and 1 of water, HO, NO5. 



Deuto-Hydrate. — In preparing this hydrate, I set out by 

 obtaining a quantity of colourless strong nitric acid, the exact 



