PROFESSOR TYNDALL’S CONTRIBUTIONS TO MOLECULAR PHYSICS. 
341 
Bisulphide of Carbon . 
Formula. 
. cs 2 
Number of atoms in molecules. 
3 
Chloroform . . . . 
. C H Cl 3 
5 
Iodide of Methyl . . . 
. C H 3 1 
5 
Iodide of Ethyl . . . 
. c 2 h 5 i 
8 
Benzol 
. c 6 h 6 
12 
Amylene 
• C 5 H 10 
15 
Alcohol 
. C 2 h 6 0 
9 
Formic Ether . . . . 
. c 3 h 6 o 2 
11 
Sulphuric Ether . . . 
. 
. c 4 h 10 o 
15 
Acetic Ether . . . . 
. c 4 h 8 0 9 
14 
Boracic Ether . . . . 
. bc 6 h 15 o 3 
25 
Here, for the first six vapours, the radiant and absorbent powers augment with the 
number of atoms contained in the molecules. Alcohol and amylene vapours, however, 
are nearly alike in absorptive power, the molecule of amylene containing 15 atoms, while 
that of alcohol embraces only 9. But in alcohol we have a third element introduced, 
which is absent in the amylene ; the oxygen of the alcohol gives its molecule such a 
character as enables it to transcend that of the amylene, though the latter contains the 
greater number of atoms. Here the idea of quality superadds itself to that of number. 
Acetic ether also has a less number of atoms in its molecule than sulphuric ether ; but 
whereas the latter has but one atom of oxygen, the former has two. Formic ether and 
sulphuric ether are almost identical in their absorptive powers for the heat here employed; 
still formic ether has but 11 atoms in its molecule, while sulphuric has 15. But formic 
ether possesses two atoms of oxygen, while sulphuric possesses only one. Two things 
here suggest themselves as influential on the absorbent and radiant power, which may 
be expressed by the terms multitude and complexity. As a molecule of multitude, amy- 
lene, for example, exceeds alcohol; as a molecule of complexity, alcohol exceeds 
amylene ; and in this case, as regards radiant and absorbent power, the complexity is 
more than a match for the multitude. The same remarks may be made with refer- 
ence to sulphuric and formic ether ; the former excels in multitude, the latter in com- 
plexity, the excess in the one case almost exactly balancing that in the other. Adding 
two atoms of hydrogen and one of carbon to the formic ether, we obtain acetic ether, 
and by this addition the balance is turned ; for though acetic ether falls short of sul- 
phuric ether in multitude, it transcends it in absorbent and radiant power. Outstand- 
ing from all others, when equal volumes are compared, and signalizing itself by the 
enormous magnitude of its absorption, we have boracic ether, each molecule of which 
embraces no less than 25 atoms. The time now at my disposal enables me to do little 
more than glance at these singular facts ; but I must direct the attention of chemists to 
the water molecule : its power as a radiant and an absorbent is perfectly unprecedented 
and anomalous, if the usually recognized formula be correct. 
