SILK-WORMS. 
145 
series of causes of deterioration of the air which the 
worms must breathe, may be termed a continued 
suu's rays, they exhale an immense quantity of vital air 
necessary to the life of animals, and which they consume by 
respiration. 
These same leaves, in the shade, and in darkness, exhale an 
immense quantity of mephitic or fixed air, which cannot be 
breathed, and in which animals would perish. 
This influence of the sun does not cease, even when the leaf 
has been recently gathered ; on the contrary, in darkness, 
gathered leaves will exhale a still greater quantity of mephi- 
tic air. 
Place one ounce of fresh mulberry leaves in a wide-neckcd 
bottle, of the size of a Paris pint (containing two pounds of 
liquid), expose this bottle to the sun about an hour after- 
wards, according to the intensity of the sun ; reverse the 
bottle, introduce a lighted taper into it, the light will become 
brighter, whiter, and larger, which proves that the vital air 
contained in the bottle has increased by that which has disen* 
gaged itself from the leaves ; to demonstrate this pheno- 
menon more clearly, a taper may be put into a similar bottle 
which only contains the air which has entered into it by its 
being uncorked. 
Shortly after the first experiment, water will be found in 
the bottle that contained the mulberry leaves ; this water eva- 
porating from the leaves, by means of the heat, hangs on the 
sides, and runs to the bottom, when cooling ; the leaves ap- 
pear more or less withered and dry according to the quantity 
of liquid they have lost. 
Put in another similar bottle an ounce of leaves, and cork it 
exactly like the former ; place it in obscurity, either in a box, 
or wrap it in clothes, in short, so as totally to exclude light ; 
two degrees after, according to the temperature, open the 
bottle, and put either a lighted taper, or a small bird into it, 
the candle will go out, and the bird perish, as if they had been 
plunged into water, which demonstrates that in darkness the 
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