536 
NOTES ON THE AIR OF BRISTOL, AND ITS ANALYSIS. 
Now, let the least preponderance be on either side, health will fail, sickness 
be generated, and the whole ruined. 
The atmosphere is a vast mechanical mixture of the atoms of oxygen and 
nitrogen, carbonic acid and ammonia, floating in a medium of the greatest 
tenuity. Two of these (oxygen and nitrogen) are constant in their proportion, 
while the carbonic acid and ammonia are very variable, always depending on 
the condition of the earth’s surface and of its living occupants. 
The normal composition of pure atmospheric air may be regarded as,— 
Oxygen. 2,096 volumes. 
Nitrogen. 7,900 „ 
Carbonic Acid .... 4 ,, 
10,000 volumes. 
The ammonia is usually present in the proportion of one-millionth. 
Like all other things, the atmosphere is subject to the law of gravitation ; 
and as the attracting force decreases as the square of the distance from the 
attracting body, so that portion of the air nearest the earth’s surface is the 
densest and possesses the greatest specific gravity. 
Calculations have shown that the greatest quantity of the atmosphere exists 
within 20 miles of the mean sea-level. 
Oxygen is of course the most important of the component gases in air, and 
the active agent by which all the offices of the atmosphere are effected, especially 
as regards animal life. 
We find it existing in two conditions, first as we commonly know it, and 
secondly as ozone. (A few experiments were exhibited to prove that at¬ 
mospheric air contained about one-fifth of its volume of oxygen gas.) 
Oxygen is most active when existing as ozone, instantly decomposing organic 
matter, possessing strong bleaching powers and a peculiar odour. 
It is found abundantly near the sea, and in the open country, but the moment 
it comes in contact with the crowded houses of a town it instantly disappears. 
The author then described the various processes for preparing ozone, and 
showed Deane’s apparatus, which he was in the habit of using in his experi¬ 
ments, and exhibited solutions of brown sugar and sulphate of indigo perfectly 
bleached by a current of ozonized air. 
The most recent ideas respecting the nature of ozone and the tests for its 
presence were explained, and the importance of ventilation and the conse¬ 
quences of an overcharge of carbonic acid were fully entered into. 
Although so great a quantity of this gas is evolved from volcanoes, manu¬ 
factories, etc., yet it is present in the atmosphere of the open country, only in 
the pretty constant proportion of 4 in 10,000, the rest being absorbed by vege¬ 
tation. 
Widely different, however is it in towns and crowded buildings, for in them 
the air is highly charged with carbonic acid. 
A closed room insufficiently ventilated soon becomes oppressive with this 
deleterious gas, which soon depresses the vital powers. 
It must also be remembered that the breath is loaded with effete organic 
matter which is rapidly putrescible; the amount in a room where many people 
have been living, being generally proportionate to the percentage of carbonic 
acid. 
With this idea in view, the author had, for some time past, occasionally ex¬ 
amined the air taken from various places in Bristol, the percentage being cal¬ 
culated from the resultant carbonate of lime or barium as the case may be. 
The actual results of nearly forty of these analyses were placed before the mem¬ 
bers, with the analytical apparatus used. 
