59 Atmometric and Hygrometric Experiments. 
bly all those absorbent powers. Thus, while in winter the . 
introduction of sulphuric acid under a receiver and in a 
room without fire, scarcely sinks the hygrometer 40 de- 
grees, it will, even in our feeble summers, occasion a dry- 
ness of 100 or 120 degrees. On this principle, water may 
be rendered cool in the sultriest climates, and in every state 
of the atmosphere; for nothing more is required than to 
expose it to evaporate from a porous vessel, in a medium 
of confined air, and near the action of a large surface of 
sulphuric acid. Nay, with that arrangement, artificial con- 
gelation is produced, if the external temperature should 
‘come but as low as 38 or 40 degrees, on Fahrenheit’s scale. 
Wine also could be cooled, by casing the sides of the bottle 
with wet flannel, and shutting it up in a wide shallow box, 
which is lined with lead or composed of glazed earthen- 
ware, and has its bottom covered, perhaps to the thickness 
‘of half an inch, with a stratum of the acid. If this box, 
with its contents, were placed in a cellar, the wine would, 
at all times in this island, have its temperature reduced, in 
the space of four or five hours, to 40 or 42 degrees by 
Fahrenheit’s scale. By the same very simple contrivance, 
wine or water might, in the tropical countries, be cooled, 
from 80 degrees on the same scale, to 55, or even lower. 
" Nor is the desiccating efficacy of the acid sensibly impaired, 
till it has absorbed an equal bulk of moisture, and has con- 
sequently on successive days occasioncd the moderate re- 
frigeration of more than fifty times its weight of wine or 
water. 
“The influence of warmth in augmenting the dryness 
of the air, or its disposition to imbibe moisture, explains 
most easily a singular fact remarked by some accurate ob- 
servers. If two equal surfaces of water be exposed in the 
same situation, the one in a shallow, and the other in a 
deep vessel of metal or porcelain ; the latter is always found, 
after a certain interval of time, to have suffered, contrary 
to what we might expect, more waste by evaporation than 
‘the former. This observation was once made the ground 
of a very absurd theory, although the real explication of it 
appears abundantly simple. Amidst ail the changes that 
happen in the condition of the ambient medium, the shal- 
Jow pan must necessarily receive more completely than the 
deeper vessel, the chilling impressions of evaporation, since 
it exposes a smailer extent of dry surface to be partly heated 
up again by the contact of the air. The larger mass being, 
therefore, kept invariably warmer than the other, must in 
consequence support a more copious exhalation.” . 
| X. Cursory 
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