350 Prof. Potter on the Laws of the Expansion of 



of the instrument becoming barely visible beyond the latter tem- 

 perature, from the strong colour of the vapour above the liquid. 

 The values of the constants below were determined for the 

 temperatures 0° C., 32°'l C, 89° C. ; so that the differences 

 between the observed and calculated volumes disappear at these 

 temperatures, and at the other temperatures commence only at 

 the third place of decimals. Values of a, b, and c 2 might have 

 been found by further investigation which would have left smaller 

 differences upon the whole, but it did not seem necessary to 

 examine further. 



a = -057963, 



b =553-2889, 



c 2 =521-2185. 



The annexed Table shows the results : — 



Temperature 

 by Centigrade 

 thermometer. 



Apparent 



volumes of 



liquid nitrous 



acid observed. 



The volumes 

 calculated by 

 the formula. 



Differences. 





 1255 

 32-10 

 49-35 

 68-50 

 89-00 



1-00000 

 101856 

 105802 

 1-08286 

 1-12462 

 1-18058 



1-00000 

 1-02186 

 1-05802 

 1-09225 

 1-13310 

 1-18058 



•00000 

 + •00330 



•00000 

 + •00939 

 + •00848 



•00000 



M. Drion found the coefficient of expansion of liquid sulphurous 

 acid to equal that of air at the temperature of about 80° C, and 

 at 130° C. it is nearly triple that of air, and the liquid is five 

 times as dilatable as at the freezing temperature. It becomes 

 entirely vapour at about 140° C. 



The values of a } b, c 2 below for liquid sulphurous acid were 

 obtained by taking the average of different determinations, and 

 they give results which still leave the differences as seen by the 

 Table annexed, commencing in the third place of decimals with 

 large numbers in some parts of the series ; but the accordance, 

 considering the corrections needed, is still sufficient, through so 

 long a series and to a point so near that of entire vaporization, 

 to enable us to conclude that liquid sulphurous acid follows the 

 law of hyperbolic expansion. With 



a = -589227, 

 b = 243-453, 

 c 2 = 100-0039, 



we obtain the results in the third column of the Table : — 



