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l 94 FRAGMEN TS 015‘ SCIENCE.

ether here employed, and 00mparing them then together,
the quantity of wave-motion intercepted by the ether would
be many thousand times that intercepted by the air.

Any one of these vapors discharged into the free atmos-
phere, in front of a body emitting obscure rays, intercepts
more or less of the radiation. A similar effect is produced
by perfumes difi'used in the air, though their attenuation is
known to be almost infinite. Carrying, for example, a cur-
rent of dry air over bibulous paper moistened by patchouli,
the scent taken up by the current absorbs 30 times the
quantity of heat intercepted bythe air which carries it;
and yet patchouli acts more feebly on radiant heat than
any other perfume yet examined. Here follow the results
obtained with various essential oils, the odor, in each case,
being carried by a current of dry air into the tube already
employed for gases and vapors :

Name of perfume. Absorption.
Patchouli................................... 30
Sandal-wood.~. . .. . . .. . . .. . . .. . . .. . . . . 32
Geranium ................................. 33
Oilofcloves.....................; ......... 34
Otto ofroses............................... 37
Bergamot ................................. 44
N eroli .................................... 47
Lavender ._ ............ . ................... 60
Lemon ........... . ....................... 65
Portugal ....... . .......................... 67
Thyme .................................... 68
Rosemary ................................ 7 4
Oil of lame] ............................... 80
Camomileflowers. .......................... 87
Cassia ............ '. ...................... 109
Spikenard ................................. 355
Aniseseed............. .................... 372

Thus the absorption by a tube full of dry air being 1,
that of the odor of patchouli difiused in it is 30, that of

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