ABSORPTION OF AIR BY WATER. 
587 
cubic indies more, with river water, plunged 
the beak into a water trough, and placed 
a snaall inveited jar (ull of water over the 
extremity of the beak. 1 then boiled the 
water till it ceased to give out any air. I col- 
lected 5*25 cubic inches of air. Baio- 
nieter at ‘29'5 inches. Thermometer 5 ^^. f 
In this experiment 168 culiic inches o 
water gave out 5*23 cubic inches (making the 
requisite corrections) of air, supposing the 
barometer at 30 inches and the thermometer 
at 60°. The 75 cubic inches which filled 
the thioat and beak of the retort became hot, 
and no doubt gave out a little air; but not 
much ; because, as soon as the water in the 
retort began to boil briskly, the water in the 
throat and beak was driven out by the steam, 
and never boiled at all. Thus, it appears 
that 100 cubic inches of Clyde water contain 
3Tl3 cubic inches of air. 
'J'he experiment being repeated in precisely 
tlie same way, the product of air was so nearly 
the same that it seems unuecessaiy to state 
the particulars minutely. 
II.-COM POSITION OF THE AIR 
THUS EXTRACTED. 
I let up lOO volumes of this air into a small 
jar, filled with water and standing over the 
water-trough, and put into it a stick of phos- 
phorus of such a 1 ngth that it reached fiom 
the bottom to the top ol the jar. and traveised 
all the air. In 24 hours the bulk of thi« air 
was reduced to 7r48 volumes of azotic gas. 
Hence, the air extricated fiom the water was 
composed of 
71*48 volumes of azotic, and 
28 52 volumes of oxygen gas. 
The air extricated during the second ex- 
periment, analyzed in the same way, was 
composed of 
70 32 volumes of azotic, and 
29 63 volumes of oxygen gas. 
If we take the mean of these two analyses, 
we get the constituents of the air extracted 
from Clyde water by boiling as follows : 
Volumes of azotic gas . . . 70*9 
A^olumes of oxygen gas . . . 29*1 
100-0 
ill.-ALTERATlON PRODUCED ON 
THIS AIR WHFN LEFT STAND- 
ING ON THE WATER-TROUGH. 
1. The 5*25 cubic inches of air extracted 
by boiling water from the Clyde, were put 
into a small cylindrical glass capable of hold- 
ing lieu' ic inches, and left inverted over 
the water trough. Every 24 iiours I cubic 
inch (or iOO volumes) of this air was taken 
out, and left till next day with a stick of 
phosphorus passing through it. The follow- 
ing table shows the composition of the air af- 
ter standing over the vvater. 
Azotic. Oxygen. 
1. Fre.sh extracted of. . 7l-48 -j- 28.52 
After one day 
After two days 
After three days 
After four days 
2 . 
3. 
4. 
5. 
2. The 5*25 cubic inches extracted from 
he second quantity of water by boiling was 
74*43 + -25 57 
75 38 + 24*62 
77*51 -f 22*49 
80 97 H- 19*03 
treated in the same way : excepting that tlie 
11 cubic inch jar containing the air, instead 
of standing open on the water-trough, was 
corked tight. The result was as follows ; 
Azotic. Oxygen, 
1. A ir newly extricated 
composed of .70*32 4- 29*69 
2. After one day . 72*5 27*5 
3. After two days . 73'44 26*54 
4. After three days . 73*35 4* 27*65 
5. After four days . 77*43 -j- 22*57 
Here, as in the first case, the oxygen was 
absorbed more rapidly than the azotic gas ; 
but the rapidity of this absorption was some- 
what diminislied by corking the glas.s in which 
the air was kept. 
IV. -ALTERATION PRODUCED ON 
COMMON AIR BY LEAVING IT 
STANDING IN A GLASS VESSEL 
INVERTED ON iHE WATER- 
TROUGH. 
Curious to know whether a similar diminu- 
tion in the quantity of oxygen in common air 
would take place when left standing over the 
water-trotigh, as had taken place in the pre- 
ceding experiments with air extricated from 
water by boiling, I put ten cubic inches of 
common air, collected at the windovv of my 
laboratory on a windy day. into a cylindri- 
cal glass jar and left it standing inverted over 
the water-trough, analyzing every day one 
cubic inch by means of phosphorus, til! the 
whole was exhausted, d'he following table 
shows the result of these analyses. 
Azotic. Oxvgea. 
1 . After standing 24 hours 79-47 -f- 20 53 
2. After two days .. .. 79 27 4-20-73 
3. After three days .. .. lost 
4. After four days .. .. 79*65 -f* 20*35 
5. After five days .... 79-65-420-35 
6 After six days .... 82*99 -j- 17-01 
7. After seven days .... 8 o-7j 19-29 
8. After eight days 80 -4-20 
9. ilfter nine days 80-84 l9*i6 
lO. After ten days 82 26 -J- 17 74 
On the ninth day, after analyzing the gas, 
1 dissolved some sulphate of iron in the water- 
trough. This is the reason of the greater 
proportion of azotic gas found in the last cu- 
bic inch of the air, which was analyzed on 
the tenth day. 
If we compare these experiments with the 
former ones, we must be struck with the great 
difference between them. The air extracted 
Iroin water by boiling is much richer in 
oxygen than common air, containing rather 
more than 29 per cent., while common air 
contains only 2o per cent, by volume. But 
this excess of oxygen diminishes rapidly ; so 
that after four days itdoes not contain more 
than common air does. 
Common air, on the contrary, may be left 
upon the water-trough for ten days without 
undergoing any sensible alteration in its 
composition, indeed I left nine cubic inches 
of air in a tube standing inverted over water, 
from the first of May to the 25th of that 
month, and found its constituents unaltered. 
If we take the mean of the constituents of 
sir from the preceding table, leaving out the 
