Bauhaus-Universität Weimar

The Cyclopaedia of Anatomy and Physiology, vol. 4: Pla [corr.: Ple] - Wri
Todd, Robert Bentley
weight, in the 1000. The air collected in the 
pit of the Opéra Comique a short time before 
the termination of the performance contained 
23 ; while in another experiment the air 
from one of the boxes contained 4* §3, by weight, 
of carbonic acid gas in the 1000. In one of 
the stables at the Ecole Militaire, the air 
collected after it had been kept closed for a 
night yielded P05 in the 100 ; and the air 
from another which was better ventilated 
yielded about 2 parts in the 1000, by weight.* 
If, according to the opinion of Leblanc and 
others, carbonic acid gas exerts a prejudicial 
effect upon the vital actions in the human 
species when it has accumulated to the extent 
of 1 per cent, in the air to be breathed, the 
above facts, to which many others might 
readily have been added, point out the im¬ 
portance of securing sufficient ventilation both 
in our private and public buildings. 
As the gases held by water in solution sup¬ 
ply the means of aquatic respiration to many 
animals and plants, a knowledge of the quan¬ 
tity and composition of these gases is also 
necessary for the full comprehension of the 
function of respiration. Humboldt and Gay 
Lussac state that the water of rivers, and dis¬ 
tilled water well aired, hold in solution about 
J^-th of their volume of air composed of about 
32 of oxygen and 68 of azote, by volume.f 
Morren j concludes from his experiments that 
sea-water contains in solution between J^th 
and Jfj-th of its volume of air, a quantity sen¬ 
sibly less than that obtained from fresh-water, 
which usually contains from to or 
even ^L-th of its volume.§ He found that the 
air obtained from fresh-water under ordinary 
circumstances, whether distilled and again 
perfectly aërated, or the limpid water of a 
moderately rapid stream, contains 32 parts of 
oxygen, and from 2 to 4 of carbonic acid, by 
volume, in the 100; while the air obtained 
from sea-water yielded 33 of oxygen and 
from 9 to 10 of carbonic acid in the 100. The 
relative proportion of the gases obtained both 
from fresh and sea-water varies considerably 
under certain conditions. In fresh-water ponds 
abounding in plants or green animalculæ, and 
in shallow parts of the sea, where numerous 
* According to the experiments of M. Lassaigne 
(Comptes Rendus, 13th Juillet, p. 108. 1846) the 
carbonic acid gas, formed by respiration in apart¬ 
ments where the ventilation is very imperfect, is not 
confined to the parts nearest the floor, but is diffused 
nearly in equal proportions through every portion 
of the mass of air in the apartments. 
f Journal de Physique et de Chimie, par Dela- 
mitherie, tom. lx. p. 158. The percentage of oxygen 
from the air of water of the Seine was 3T9 ; of dis¬ 
tilled water which had again absorbed air, 32-8; 
and of rain water* 3L0. (p. 159.) 
J Annales de Chim. et de Phys., tom. xii. 1844. 
§ M. Lewy (Comptes Rendus, 28th Sept. 1846) 
states that, in his experiments, one litre (61-027 
cubic inches English) of Seine water yielded about 
40 Cubic centimetres (2-440 cubic inches) of air, and 
the same quantity of water from the ocean furnished 
only 20 cubic centimetres (1-220 cubic inches). The 
water of the ocean, in consequence of the salts it 
holds in solution, absorbs much less atmospheric 
air than fresh water. 
algæ flourish, the proportion of oxygen gas 
may be considerably increased during sun¬ 
shine, especially if the water be at the same 
time still. Morren analyzed, in a bright day 
in July, the gas dissolved in the water of 
a fish-pond of a green colour, chiefly from 
the numerous animalculæ it contained, and 
found in that procured in the morning 25, at 
mid-day 48, and in the evening as much as 61 
of oxygen in the 100 parts.* Similar changes, 
but to a less extent, were detected by Morren 
in the air of sea-water, and they are chiefly 
dependant upon the action of the algæ. In 
one experiment, performed on a fine sunny 
day, when the sea was at the same time calm, 
the air obtained from the water yielded 40 per 
cent, of oxygen in the early part of the day, 
and 53’6 in the evening. The total quantity 
of air obtained from both kinds of water varied 
at different times of the day ; and its increase 
was chiefly dependant upon the addition of 
oxygen, the carbonic acid at the same time 
suffering a decrease, but not in the same pro¬ 
portion, while the nitrogen f seemed to suffer 
little change. This increase of oxygen will 
partly contribute to the supply required for 
the respiration of the numerous aquatic ani¬ 
mals which usually frequent the localities 
where it is evolved, and be partly given off to 
the superincumbent air, and thus assist in 
maintaining the purity of the atmosphere. 
Notwithstanding the large quantity of oxy¬ 
gen daily removed from the atmosphere by the 
respiration of animals and other causes, yet 
from the great extent of the atmosphere, and 
the rapid mixture of its different parts, a long 
period of time must necessarily elapse before 
it suffers any marked deterioration, even were 
there no compensating operation in the vege¬ 
table kingdom. The oxygen gas in the atmo¬ 
sphere is equal in weight to a column of 7'8 
feet of water pressing upon every part of the 
earth’s surface : and it has been stated that it 
would require 10,000 years, supposing the 
earth peopled with 1,000,000,000 of men to 
produce a perceptible effect upon the eudio¬ 
meter of Volta, even though vegetable life 
was annihilated ; and that to suppose all the 
animals on the surface of the earth could by 
* Opus cit. p. 9. Wohler (Poggendorff’s Annalen 
der Physik und Chemie, hand lvii. S. 308. 1842) 
analyzed the gas exhaled from the greyish yellow 
mass, consisting in a great measure of living infu¬ 
soria mixed with some confervæ, which collects in 
a salt spring at Rodenberg in Hesse, and found it to 
be composed of 51 per cent, of oxygen, and 49 of 
■f M. Lewy (Comptes Rendus, 28th Sept. 1846) 
has observed similar changes, but not to the same 
extent, in the relative proportions of oxygen and 
carbonic acid in the air of sea-water under the cir¬ 
cumstances mentioned by Morren. According to 
the results of Lewy, the waters of the ocean contain 
a small quantity of sulphuretted hydrogen gas, ap¬ 
parently evolved from the bodies of certain mollus¬ 
cous animals, which may be imparted to the air 
resting upon the surface of the water ; and Dumas, 
in his report upon Lewy’s Memoir, throws out some 
remarks on the possibility of the sulphur contained 
in this gas serving an important purpose in the 
nutrition of plants.


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