ON EVAPORATION AND DISSOCIATION. 
107 
Series VI. — Pressure raised by admitting Aldehyde-vapour, prepared at the time 
from Aldehyde-ammonia and Sulphuric Acid, and dried over PAD. 
Pressure. 
Temperature. 
Pressure. 
Temperature. 
Pressure. 
Tempciature. 
millims. 
millims. 
millims. 
8-45 
42-1 
67-5 
63-9 
309-9 
75-1 
10-15 
44-3 
99 7 
65-8 
3481 
76-3 
23-6 
•54-2 
139-8 
68-8 
403-1 
77-7 
37-7 
59-1 
175-1 
70-8 
462-4 
78-9 
44*4 
61-0 
215-8 
72-1 
553-1 
80-3 
49-8 
62-0 
266-0 
73-9 
616-9 
81-4 
When air or aldehyde was admitted to raise the pressure the cotton-wool became 
discoloured by a brown resinous substance ; this was not the case when the pressure 
was raised by admitting ammonia-gas (Liubawin, ‘ Berichte,’ 8, p. 1684). Although 
the results obtained on raising pressure with air, ammonia, and aldehyde are somewhat 
divergent, yet a very large difference of pressure is caused by a slight alteration in 
temperature, and the results of observations with any one of these substances show 
equal discordance among each other. This is not surprising considering the nature of 
the compound. (Plate 2.) 
§ 61. Vapour-densities of Aldehyde-ammonia. 
The vapour-densities were determined by Hofmann’s method at 78'25° and at 
131 - 8°. 
Weight. 
Temperature. 
Pressure. 
Volume. 
P.Y. 
Vapour-density. 
Percentage number 
of molecules 
decomposed. 
millims. 
cub. eentims. 
0-0353 
78-25 
294-1 
73-06 
21,487 
17-93 
70-11 
5 ? 
?) 
280-0 
76-86 
21,521 
17-90 
?? 
A long time had to elapse before pressure became constant and the vapour acquired 
its maximum volume. 
Weight. 
Temperatu e. 
Pressure. 
Volume. 
P.V. 
Vapour-density. 
Percentage number 
of molecules 
decomposed. 
0-0353 
131-8 
millims. 
324-1 
cub. eentims. 
79-78 
25,857 
17-17 
77-64 (?) 
A certain amount of yellow resin had deposited on the surface of the mercury at 
the higher temperature, which accounts for the dissociation being apparently incom¬ 
plete. At the lower temperature no decomposition was observed. 
p 2 
