52 Stoux City Academy of Science and Letters. 
this multiplicity of questions arising out of a study of 
ventilation, I have contented myself with some slight 
study of the presence of carbon dioxide in the air of the 
school rooms, believing that the amount of carbon diox- 
ide present is a pretty accurate index of the degree of 
impurity or ventilation of the air. 
The buildings chosen were: The High School, in 
which is used the Smead system with a rotary fan for 
forcing the air; the Longfellow building, in which is used 
the Smead system without the fan, the so-called gravity 
system; the Whittier building, in which is found a hot 
air system with return air from a part of the rooms and 
an exit opening from each room connecting with the 
outer air, and the Cooper building, in which the heating 
is by means of steam and in which, as is usually the case 
with steam heated buildings, there is but little thought 
for ventilation. 
The method employed in the tests was to admit a 
few cubic centimeters of standard K O H solution into a 
flask containing air from the school room. The flask 
being then shaken violently for from three to ten minutes 
during which time the K O H absorbs all of the C O, 
present. The alkalinity of the K O H is thereby lessened. 
Enough of a standard H, S O, solution is now admitted 
to the flask to exactly neutralize the K O H. The amount 
of the acid thus needed deducted from the amount need- 
ed to neutralize the K O H without the presence of the 
C O, will leave as a remainder the amount of C O, which 
was actually present in the flask to unite with the K O H. 
Knowing the capacity of the flask it is an easy matter 
to reduce to a basis of 10,000 parts, corrections being 
made for temperature and pressure. During the pro- 
gress of the experiments, due caution was observed to 
keep the solutions and the air in the flasks from contact 
with the outer air. 
In the samples of air from the High School Assem- 
bly room it was found that 6.85 parts of CO, were pres- 
ent in 10,000 parts of air. In Longfellow 7.51 parts were 
found and a second determination in which only three 
rooms were tested, in two of which the conditions were 
