69 
sufficient quantity through. If it is made to pass rapidly, 
absorption does not take place , and evaporation of the 
water is the consequence; if it passes slowly, it requires 
several weeks to pass a hundred cubic feet through a small 
quantity of water. I continued the experiment for three 
months, but although I obtained sulphuric acid, chlorine, 
and a substance resembling impure albumen, I did not get 
enough to make a complete examination; and indeed this 
could not be expected, as I found that in that time less than 
a thousand gallons of air had passed through. 
“When this exhalation from animals is condensed on a 
cold body, it in course of time dries up, and leaves a some- 
what gelatinous organic plaster; we often see a substance 
of this nature on the furniture of dirty houses, and in this 
case there is always a disagreeable smell perceptible.” — 
Mems.: Brit . Association , Meeting held in August , 18 AS. 
I quote the words used by the President of the Associa- 
tion simply to show that the paper was well known : 
“ F or instance, the causes which in our great cities hasten 
the death and debase and embitter the life of so many, have 
at last been forced by chemists and physiologists on the 
notice of the public. Look at Dr. Smith’s report on the air 
and water of towns, in this volume ; and when we think 
that the victims of the deadly influences which are there 
revealed are chiefly found among the people whose industry 
is the foundation of our greatness, — that every year cut off 
from the life of each of these is so much subtracted from 
national wealth, — even were all moral sense and religious 
feeling dead in us, we must confess that the knowledge 
which is capable of averting them ‘ is of use.’ ” 
Looking over these words at this distance of time it 
seems to me scarcely possible to write more clearly, 
although some of the words I should prefer to see changed. 
Still the subject was a continued study, and it was my 
strong desire to measure exactly the amount of organic matter. 
