70 
Before introducing the calcium chloride the inner surface of the 
bottle was covered with moisture. This disappeared in about 15 or 20 
minutes after the drying apparatus was introduced. 
Naturally a little formaldehyde was lost by displacement and diffu- 
sion when the drying tray was introduced and withdrawn. This loss 
could not have been more than a small fraction of the amount of 
formaldehyde in the bottle when the crucible was removed. 
After withdrawing the drying apparatus, potassium cyanide solu- 
tion was measured into the bottle from a burette through an inch 
hole in the stopper. To prevent loss, the burette tip was passed 
through a small hole in a flat cork, which in turn fitted into the hole of 
the stopper, thus closing the mouth of the bottle. After removing 
the burette, the hole in the stopper was properly closed with a cork. 
The subsequent procedure was exactly like that described above 
(p. 66). ^ . ■■ / v 
The formaldehyde left in the residue in the crucible was also deter- 
mined in the manner already described (p. 67). 
Table 7. — Experiments on drying formaldehyde gas in 18 -liter bottle by calcium chloride. 
Experiment. 
Formalin 
40 per 
cent by 
volume. 
KMnOj 
pow- 
dered. 
Time of dry- 
ing. 
Formal- 
dehye 
found in 
bottle. 
Formal- 
dehyde 
found in 
residue. 
I 
c. c. 
0.7 
.7 
.7 
. gm. 
0.35 
.35 
.35 
1 hour 
Per cent. 
21.12 
20.06. 
14. 76 
Per cent. 
33.86 
32.52 
35.87 
II 
1 hour 
Ill 
hours 
II 
Since the bottle was charged in precisely the same manner and 
with the same quantities as in experiments IV, V, VII, and VIII, 
Table 6, we may assume that the average of these four results, 
namely, 36.71 per cent is the quantity of formaldehyde in the bottle in 
the present experiments before drying. The results of experiments I 
and II, Table 7, are fairly close, the average being 20.59 per cent. The 
difference, 16.12 per cent is the loss, due mainly to drying and, in 
a small degree, to escape by introduction and removal of the drying 
apparatus. It is probable that more than one-third of the formalde- 
hyde disappeared by the drying during 1 hour. By 2 hours’ drying 
still more disappeared, as shown in experiment III. 
The question as to what becomes of the formaldehyde that disap- 
pears is an interesting one; but it was not investigated. After the 
calcium chloride had been removed from the bottle it was stored in a 
closed jar. This jar had a strong odor of the gas. It is probable that 
some of the formaldehyde was held as such in the pores of the cal- 
cium chloride granules. Whether the latter also had a polymerizing 
effect on the formaldehyde we are not able to say. 
