458 Mr. Smith on the Hydrates of Nitric Acid, 



amount of real acid in which was ascertained by saturation to 

 be 79*79 per cent. To reduce this acid to the proper strength, 

 so as to contain exactly 2 equivs. of water, it was found by 

 calculation that it would require 63*86 grs. of w'ater to every 

 1000 grs. of acid. 



The proper proportions of acid and water were weighed out 

 carefully in a stoppered specific gravity bottle, and the two 

 mixed. This mixture was cooled down to 60° and found to 

 have the sp. gr. 1*486. 



50 grs. of this hydrate were weighed out and saturated in 

 the usual way with recently-ignited carbonate of soda. The 

 quantities of carbonate of soda required were as follows : — 

 Exp. Carb. of soda. Mean. 



2* ' ' 37*53 y^^*^^' °^ ^^'^^ P^^ *^^°^* ^^^^• 



An acid containing 2 equivs. of water will contain 75 per 

 cent, real acid. 



A portion of this acid was introduced into a small retort 

 and distilled. It began to boil, as nearly as could be judged, 

 at about 200°, it being difficult to come at the exact tempera- 

 ture on account of the very rapid rise of the thermometer, 

 which continued to take place until it had gained the tempe- 

 rature of 218°; it afterwards rose when near the end to 250°. 



It appears, then, from these experiments, that no such thing 

 as a deuto-hydrate exists, but that when a mixture is made 

 in the proportions to form such a hydrate and subjected to di- 

 stillation, it divides spontaneously into the first and another, 

 at the same time suffering considerable decomposition ; and 

 the acid which is found remaining in the retort has the exact 

 boiling-point of the tetra-hydrate, namely, 250° ; and more- 

 over, the first portion that came over had the exact density , 

 of the first. 



A portion of this acid placed in a freezing mixture of ice 

 and salt, suffered not the least solidification. 



Tetra-Hydrate. — This hydrate was prepared in the same 

 way as the first, namely, by preparing a quantity of colourless 

 acid, ascertaining its saturating power, and mixing it with the 

 proper quantity of distilled water, ascertained by calculation. 

 It was then tried afterwards by saturation to see if it was 

 correct ; the numbers below will show the difference : — 

 Exp. Cavb. ofsoda. Acid. Mean. 



\'. \ '. 29*87 = 30*27 }^^'^2' ^"^ ^^'^"^ P^"" ''^''^- ""^^^ ^'''^- 



According to theory with 4 eqs. water. 

 Real acid . . 60*64 Real acid ... 60 



Water , , . 39*36 Water .... 40 



100*00 100 



