82 
PEOFESSOE TTNDALL ON THE ABSOEPTION AND 
over them for some minutes. They were then connected with the experimental tube, 
which had its sources of heat arranged as already described. The tube was first 
exliansted and the needle brought to 0°, and dry air was then passed over the scented 
herbs until tlie tube was filled. The consequent deflection was noted, and from it the 
absorbent action of the odorous substance was deduced. 
Thyme thus treated exercised thirty-three times the absorption of the air in which it 
was difiiised. 
Peppermint exercised thirty-four times the action of the air. 
Spearmint exercised thirty-eight times the same action. 
Lavender produced thirty-two times the action of the air. 
Wormwood forty-one times the action of the air. 
The follomng perfumes were obtained from Mr. Atkinson of Bond Street, and examined 
in this manner. Small squares of dried bibulous paper, all of the same size, were rolled 
into cylinders about 2 inches in length ; each of these was moistened by an aromatic oil, 
and introduced mto a glass tube between the drying apparatus and the experimental 
tube. The latter being first exhausted, was afterwards filled by a current of dry air 
which had passed over the scented paper. Calling the action of the air which formed 
the vehicle of the perfumes 1, the following absorptions were observed in the respective 
cases : — 
Table VII. 
ne of perfume. 
Absorption. 
Pachouli 
... 30 
Sandal Wood . 
... 32 
Geranium . 
... 33 
Oil of Cloves . . 
. . . 33-5 
Otto of Boses . 
. . . 36-5 
Bergamot . 
... 44 
Neroli .... 
... 47 
Lavender . . . 
... 60 
Lemon .... 
... 65 
Portugal 
... 67 
Thyme .... 
... 68 
Bosemary . 
... 74 
Oil of Laurel . . 
... 80 
Cassia .... 
... 109 
It would be interesting to examine the absolute weights of the substances which pro- 
duced these efiects ; but this I suppose is a tashj which chemistry is unable to accom- 
plish. In comparison with the air which carried the odours into the tube, their weight 
must be almost infinitely small. Still we find that the least energetic in the list has 
thirty times the effect of the air, while the most energetic produces 109 times the same 
