492 Mr. J. Y. Buchanan on the Absorption of 



into the absorption-tube, should be deprived of air without affecting 

 their state of concentration. This was effected in the following way. 

 A flask was filled up to a mark in the neck with the solution, half of it 

 was then emptied into another flask and the two boiled, while distilled 

 water was kept boiling in a third. When the boiling had been kept up 

 for about half an hour, the contents of the second flask were emptied 

 into the first and washed out with the hot distilled water, the volume of 

 the solution being brought in this way up to the mark, and so far above 

 it as was equivalent to the expansion of the solution for the difference of 

 temperatures. A glass syringe of convenient size was now filled with 

 the boiling liquid and passed hot into the absorption-tube. This method 

 may be objected to on two grounds : first, that there is some uncertainty 

 about the exact concentration of the solution when introduced into the 

 absorption-tube ; and, second, that some air may have been absorbed by 

 the liquid in its passage through the syringe to the tube. As to the 

 first objection, when the operation is carried out in the Avay I have 

 described, the possible difference between the actual and assumed con- 

 centration is so small that it w r ould be extremely unlikely to have any 

 influence on the coefficient of absorption of the liquid. As to the second, 

 if the manipulations be expeditiously carried out, there is but little fear 

 that the liquid at so high a temperature, and exposed to the small quan- 

 tity of air of diminished tension in the syringe, should be contaminated 

 in an appreciable way. However much or little importance one may 

 attach to these possible sources of error, they probably explain why the 

 whole subject has been left almost entirely untouched. 



Our object in these experiments is, not to determine the absorption- 

 coefficient for a standard pressure such as 760 millims., but to determine 

 it for various pressures, the temperature being kept as uniform as cir- 

 cumstances will permit, and to compare the results obtained with those 

 calculated for distilled water. 



Let V=volume of gas (at and 760 millims.) before introduction 

 of solution, 



V x = volume (reduced to 0) of gas after absorption, 



P l= = pressure of this gas, 

 then the volume of gas absorbed will be 



And if Ti be the volume of the solution, we have for the coefficient of 

 absorption at pressure P x and the temperature of observation, 



^ 



Two series of experiments were made on solution of sulphate of 

 magnesia containing 1*23 per cent, crystallized salt, and one series on 

 sulphate-of-liine solution containing 0*205 per cent, of CaS0 4 +2H 2 0. 



