ON EVAPORATION AND DISSOCIATION. 
317 
The results of other observers* are :— 
Dumas and Peligot, at 20° . 
Kegnault, at 15-20° . . . 
Deville, at 9°. 
Kopp (1845), at 0° . , . . 
Perkin, at 15°/15°, 079726 ; 
0798 Kopp (1847) 
0-813 Kopp (1855) 
0’807 Pierre, at 0° 
0-8147 Mendeleeff 
at 25°/25°, 078941. 
0-8180 
0-8142 
0-8207 
0-8206 
Perkin’s results give, when compared with water at 4°: at 15°, 079658 ; at 25°, 
078714 ; they are in close accordance with ours. 
The portion of methyl-alcohol A gave the following measurements ■ 
Volume. 
At 18-2° ....... 0-27622 c.c. 
22-4°. 0-27697 „ 
80‘0°. 0-29666 „ 
From these numbers a curve was constructed, and the volume at 22'94° was read : 
it was 0-27701 c.c. The specific gravity at 22 - 94° was found to be 078909 ; hence 
the weight of portion A was 0"21858 gramme. 
The volume-tube was a new one, 35 centims. long, and about 1"1 millim. internal 
diameter; the external diameter was about 8 millims. It was carefully calibrated by 
weighing with mercury at a known temperature. 
The following corrections were applied :— 
For volume.—Meniscus of mercury and of liquid. 
Expansion of glass by heat. 
The expansion of the tube owing to internal pressure was not 
allowed for, as no data are available. It is probable that any 
correction would have been within the limits of error of reading. 
For pressure.—A low-pressure and a high-pressure manometer were employed ; 
where possible, readings on both were taken. The manometers 
were calibrated by weighing with mercury, and contained air 
dried over phosphorus pentoxide. 
Corrections.—Meniscus of mercury. 
Difference of levels of mercury in volume-tube and in pressure-gauges. 
Difference in temperature of water-jacket at time of filling and time 
of reading. 
Deviation of air from Boyle’s Law, as determined by Amagat. 
For temperature.—The data given by us in the £ Chem. Soc. Trans.,’ 1885, p. 640, 
* Lossen gives a tabulated statement of boiling-points and specific gravities in the ‘ Annalen der 
Phvaik und Chemie,’ vol. 214, p. 104. 
