Some Physical Properties of Nitric Acid Solution*. 93 



VI . Contractions. 



From the density determinations the contractions in the formation 

 of 1 gramme of the acid solutions have been calculated. The volumes 

 occupied by 1 gramme of water at the temperatures of 4, 14'2 and 24'2 

 are taken from Rosetti's tables as at 1, 1*00075 and 1*00268 c.c. respec- 

 tively, while those of 100 per cent, acid are calculated with slight 

 corrections from the density values obtained for the 99 '97 per cent, acid 

 previously prepared. Owing to the difficulty experienced in elimina- 

 ting the last fractions per cent, of water from the acid no attempts were 

 made to obtain another sample ; therefore, if there had been an error 

 in these density determinations the values for all the contractions 

 would be uniformly increased or diminished, but the conclusions to J>e 

 drawn therefrom not materially affected. 



As it has been shown in the previous sections that from various 

 causes differences in value occurred of some units in the fifth place of 

 decimals in the density determinations, these figures were omitted as 

 inconsequent for the purpose of calculation, and the results expressed 

 in 1/100,000 c.c. 



The results are calculated by means of the formula 



c = pV/IQO + (100 -^)Vi/100 - V 2 , 



wherein p = percentage of acid, V = volume occupied by 1 gramme 

 of acid, Vi = volume occupied by 1 gramme of water, and V 2 the 

 reciprocal of the density for any particular mixture. 



The details of one calculation are given for an example : 



Percentage of acid = 61-53, of water = 38 -47. 

 Volume occupied by 1 gramme of water at 14 '2 C. = 1 '00075 c.c. 



Volume occupied by 1 gramme of 100 per cent, acid at 14 '2 C. 

 = 0-65679 c.c. 



/ "p. 



Volume occupied by mixture I = - ) at 14' '2 C. 0-72383 c.c. 



joV/100 = 0-40412 c.c. 

 (100-j)Vi/100 = 0-38499 c.c. 



Sum = 0-78911 c.c. 



V 2 = 1/D = 0-72383 c.c. 

 Contraction C = 0*06528 c.c. or 6528 x 10~ 5 . 



