PROFESSOR TYNDALL’S CONTRIBUTIONS TO MOLECULAR PHYSICS. 337 
Placing these results beside those recorded in Table IX., the manner in which they 
check each other will appear. 
Comparison of Tables IX. and X. — Absorption. 
Table IX. 
Table X. 
Bisulphide of Carbon 
... 4-7 
4*7 
Chloroform . . . 
... 6-3 
6-5 
Iodide of Methyl . . 
... 9-7 
9-6 
Iodide of Ethyl . . 
. . . 17*8 
17-7 
Benzol 
. . . 20-4 
20-6 
Amylene . . . . 
. . . 27-3 
27-5 
The agreement, it will be seen, is as perfect as could be desired. 
Augmenting the opening through which the heat passed from the source into the 
experimental tube, the total heat was increased, and the experiments with a few of the 
vapours were repeated. The total heat in the last case produced a deflection of 78°, 
which is equal to 350 units; the total heat now employed produced a deflection of 
83°, which is equal to 605 units. 
It is easy to see that the experiments now to be 
recorded furnish a direct check on 
the calibration of the galvanometer. As long as 
the quality of the heat remains unchanged, the absorption ought to be the same with a 
high total heat as with a low one. 
But if experiment show that this is the case, it 
proves also that the calibration on 
which the calculation of the absorption depends, 
cannot be in error. The following results were obtained on the 8th of October 
Table X «. 
Deflection. 
Absorption. 
Amylene . . . . 
... 6-0 
28-7 
Alcohol 
. . . 66-4 
29-2 
Formic Ether . . . 
. . . 68-5 
32-5 
Formic Ether . . . 
. . . 68-5 
32-5 
Sulphuric Ether . . 
. . . 69-2 
33-6 
Sulphuric Ether . . 
. . . 69-1 
33-4 
Acetic Ether . . . 
. . . 69-7 
34-5 
Acetic Ether . . . 
. . . 69-7 
34-5 
Total heat .... 
. . . 83-0 
100-0 
Placing the results beside those 
recorded in Table X., we 
have the following com- 
parison 
Comparison of Tables X. and X a. 
Amylene .... 
. . . 27’5 
28-7 
Alcohol ..... 
. . . 28*1 
29-2 
Formic Ether . . . 
. . . 31-4 
32-5 
Sulphuric Ether . . 
. . . 31-9 
33*5 
Acetic Ether . . . 
. . . 34-6 
34-5 
2 z 2 
