40 
during cold weather, but simply as showing that under these conditions 
it possesses a slight advantage over the undiluted formalin-perman- 
ganate method. 
Except under the conditions as stated, the addition of the water is 
a disadvantage, as the percentage of formaldehyde liberated is dimin- 
ished in proportion to the quantity of water used, and, furthermore, 
a larger quantity of permanganate is required. 
III. RETORT WITHOUT PRESSURE.^ 
The formalin in this method is simply heated to the boiling point 
under atmospheric pressure in a retort, and the issuing water vapor 
and formaldehyde gas are passed into the room through a suitable 
tube. 
In the following experiments 600 c. c. of formalin, to which were 
added 6 c. c. of glycerine, were taken for the charge, and the heat was 
continued under the retort until vapor practically ceased to issue from 
the outlet tube. 
When the retort was removed, there was practically no liquid left 
in it. The time required to vaporize the formalin varied from 1 hour 
to 1 hour and 10 minutes in the different experiments, depending upon 
the degree of the temperature. 
Chemical determinations . — These determinations were made by 
drawing air from the room, beginning usually a short time after 
exhausting the retort ; however, two were made after waiting 3 hours 
and 40 minutes, and 72 hours, respectively. The method of pro- 
cedure has been described, page 11. 
The results are shown in the following table: 
Table 3. — Experiments with the retort without pressure. 
Number. 
Temperature of room 
before experiment. 
Time required to ex- 
haust retort. 
Time between remov- 
al of retort and 
drawing air. 
Time required to 
draw air. 
Volume of air drawn, 
in liters. 
Relative humidity 
beiore experiment. 
Relative humidity at 
end of injection. 
Increase in grains of 
moisture per cubic 
foot. 
Abs. formaldehyde 
used per cubic foot. 
Abs. formaldehyde 
found per cubic foot. 
Per cent yield. 
Condition of wind. 
°F. 
h. m. 
h. 777 . 
h. 777 . 
gm. 
gm. 
I 
73 
1 0 
0 22 
1 6 
10 
73 
86 
1.5 
0. 107 
0. 05037 
47.07 
Very slight 
breeze. 
Ila 
76 
1 0 
0 21 
1 10 
10 
82 
89 
0.96 
.107 
. 04935 
46.12 
Do. 
II& 
3 40 
1 4 
8 
. 107 
. 04183 
39.1 
Do. 
He 
72 0 
1 7 
10 
. 107 
. 00637 
5.95 
Strong wind July 
29, 30, 31. 
III 
40 
1 10 
0 15 
1 20 
12 
52 
69 
.67 
. 107 
. 01982 
18.4 
Light wind. 
a The retort used is the Trenner-Lee formaldehyde disinfector, manufactured by J. 
Ellwood Lee Company, Conshohocken, Pa. 
