

INFLUENCE OF CARBONIC ACID GAS ON HEALTH OF PLANTS. 61 

‘With reference to the proportion of carbonic acid which water would abstract 
_ from air containing diffused through it so large an amount as 5 per cent. of 
this gas, the principles upon which such a problem may be determined have 
been long ago clearly laid down by Dr. Dalton. 
As neither carbonic acid, oxygen, or nitrogen are retained in water by vir- 
tue of any chemical affinity, but simply in the ratio of their respective elas- 
ticities, it follows that the quantity of these gases present in it will be regu- 
lated by the amount of each existing at the time in the superincumbent air. 
We know by experiment, that water would retain nearly about its own vo- 
lume of carbonic acid; 0°65 of its volume of oxygen; and 0°42 of nitrogen; 
under the pressure of an atmosphere consisting wholly of the gas so retained. 
If therefore we suppose the atmosphere in former times to have consisted 
of carbonic acid 5 per cent. and of common air, maintaining its present con- 
stitution, 95, that is, of— 
Maines d2 aise. (st. Sees cd 
epee lieww. soso. 1. Sede TD 
Carbonic aeidss. icici. Arak 5 
the quantity of each gas retained by a volume of water under such circum- 
stances would be as follows :— 
PUB OD, sis: velicdew simistawin sine 1OS102 
QR ye Riis nissan ne melew we SOLZRS 
Carbonic acid ............ °05300 

09727 * 
Water therefore under an atmosphere of this constitution would still con- 
tain nearly as much oxygen as it does at present, and not more than ‘05, or 
zp Of its volume of carbonic acid, so that the condition of the gas expelled 
from the water would be such, as to consist in 100 parts of— 
Carbonic acid .............. 545 
RUE ss hai cin sete aks oi pain a So 
Os gS te Aso winin ene «ato 
00:0 
_ Now I am enabled to prove, that a much larger proportion of carbonic acid 
than that supposed may exist in water without affeeting the health of fish at 
the present time. On one occasion indeed I agitated some river water in a 
closed vessel with a mixture of common air and carbonic acid, in the propor- 
tion of 1300 of the former to 100 of the latter, or in an atmosphere containing 
7 or 8 per cent. of carbonic acid, and found that a number of Minnows intro- 
duced into the water so impregnated died within twenty-four hours, although 
29 cubic inches were found by experiment to have taken up only 1 cubic 
inch of carbonic acid, which is in the ratio of 2°5 per cent. 
_ Nevertheless it was afterwards found by a number of experiments, that 
other fish, such as Perch and Roach, would live in water which contained from 
5 to 10 per cent. of carbonic acid, the larger of which quantities would be 
nearly double that which has been shown to be taken up by water under a 
»pressure of 5 per cent. of the latter gas. On the other hand, where the 
’ * As will appear by the following equation :— 
f 
Nitrogen’ sss cieiedbcdesesess ade eevee 76X 042=:03192 
Oxygen...... decepeccuspesenevaves sees 19 X 065="01235 
Carbonic acid PUPP CRETE Se DEeeO DEF ee8 05 x 1:06=:05300 
°09727 
