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IV. The Carbonic Acid, Organic Matter, and Micro-organisms in Air, more especially 
of Dwellings and Schools. 
By Professor Thos. Oarnelley, D.Sc., and J. S. Haldane, M.A., ALB., University 
College; and A. M. Anderson, M.D., Medical Officer of Health, Dundee. 
Communicated by Sir Henry E. Koscoe, F.R.S. 
Received June 10,—Read June 10, 1886. 
[Plate 6.] 
It has been fully proved that the habitual breathing of air vitiated by the presence of 
human beings has a most important effect on the death-rate. We nevertheless possess 
as yet scarcely any accurate data as to the connection between the death-rate and the 
quantities of such impurities as it is at present possible to measure. Nor, so far as we 
are aware, have any systematic observations been made as to the relative amounts of 
these impurities in different samples of vitiated air. 
The quantity of carbonic acid (or of carbonic acid and oxygen in more refined investi¬ 
gations) is usually taken as a measure of the total impurity. It is, however, highly 
improbable that an increase in the carbonic acid and a slight diminution in oxygen 
materially affect the death-rate (cf. Hirt, ‘ Die Krankheiten der Arbeiter/ 1873). 
The organic matter and micro-organisms in the air are in all probability far more 
important factors. 
The original object of the present investigation was to examine systematically the 
air of various classes of houses with the view of comparing the amounts of carbonic 
acid, organic matter, and micro-organisms with one another, and with the death-rates 
in the same classes of houses. During the progress of our work, however, several 
additional questions presented themselves, and the actual scope of the research has 
therefore been as follows :— 
1. An investigation of the outside air so far as was necessary for purposes of" com¬ 
parison with the determinations made inside buildings. 
2. A comparison of the quantities of the above-mentioned constituents of the air in 
one-roomed, two-roomed, and the better class of houses with one another, and with 
the death-rates and relative frequencies of various diseases in the several classes of 
dwellings. 
3. An examination of the air in schools, with special reference to the cubic space 
MDCCCLXXXVII.—B. 27.4.87 
