•2,39 



VOL. LXXII.J PHILOSOPHICAL TRANSACTIONS. 



With regard to the nitrous acid, I found also I had been a little too precipitate 

 as to the time of examining its density, after it had been mixed with water. 

 Hence using some whose specific gravity was 1.47 4, I allowed the mixtures to 

 rest 12 hours, till it was diluted with twice its weight of water, and the subse- 

 quent mixtures 6 hours at least, by the former process of reasoning, I found 

 the specific gravity of the mere nitrous acid to be 5.530; the constant number 

 in the column of acid being here 3Q3. 



The foregoing experiments were made at the temperature of between 50 and 

 60° of Fahrenheit ; but as it may be suspected that the density of the above acids 

 is much altered at degrees of temperature considerably different, I endeavoured 

 to find the quantity of this alteration, and to calculate what this density would 

 be at 55°, that the quantities of acid and water may thence be investigated. To 

 this end I took some dephlogisticated spirit of Deg. Sp. gravity, 



nitre, and examined its specific gravity at dif- ^9 i.46'50 



' r ° J 46 1.4587 



ferent degrees of heat, and found it as annexed, §6 ........ U4302 



viz. at 12 ° 1-+123 



Therefore the total expansion of this spirit of nitre from 30 to 120°, that is, 

 by 90 of heat, was 0.0527; for 1.4650 — 1.4123 = .0527; by which we see 

 that the dilatations are nearly proportional to the degrees of heat; for beginning 

 with the first dilatation from 30 to 46°, that is, by l6° of heat, 90 : 0.0527 - 16 



