314 
PROFESSOR W. RAMSAY AND DR. S. YOUNG 
greater part was obtained, boiling at 647°, under 760 millims. pressure. The rise of 
temperature did not exceed 0‘05° during the complete distillation. 
The boiling-point of methyl-alcohol has been a subject of much dispute. Kopp 
found, with three separate samples, 65°, 65°-65'2°, 64'6°-65‘2°; Pierre, 66'3°; 
Mendeleeff, 66°; Delffs, 66 - 5°; Dumas and Peligot, 66‘5°; Landolt, 66’3°; 
and Dittmar and Stewart, 64T°. Perkin, who dried his alcohol with copper 
sulphate, found 65'8°—66°; but we found that several weeks’ standing over copper 
sulphate produced little effect. Pegnauet, who dried his alcohol over lime, found 
6678°; and Schiff found 64 - 8° at 763 millims. pressure. There can be little doubt 
that the last is correct. 
Apparatus employed. —The apparatus for determining vapour-pressures at low 
temperatures was that described in the ‘Phil. Trans./ 1884, p. 37; and in the 
‘ Chem. Soc. Trans.,’ 1885, p. 42. The vapour-densities at low temperatures were 
determined by a modification of Hofmann’s apparatus, whereby pressure, volume, 
and temperature could be altered at will. This apparatus has been described in our 
memoir on ether (‘Phil. Trans./ 1887, A, p. 59). The constants at high temperatures 
were determined by a modified Andrews’ apparatus, of which a description is to be 
found in our paper on ether. 
Experimental results. —Before giving experimental results, it should be noted that 
in every case the temperatures are those of an air thermometer; the pressures refer 
to the latitude of University College, Bristol (51° 27' 25 // N.), and to 226 feet above 
sea-level ; they are corrected according to Amagat’s experiments (‘ Comptes Bendus/ 
vol. 99, p. 1153), and are measured in actual millimetres of mercury. 
Vapour-pressures at low temperatures. —The thermometer employed for tempera¬ 
tures below 40° was graduated in tenths of a degree. By reduction of pressure an 
apparent fall of temperature of 0 - 25° for 760 millims. was observed. This apparent 
fall is proportional to the pressure, and correction was applied accordingly. The 
thermometer was standardised by a determination of the vapour-pressures of water 
above 0°; and it was assumed that the graduation below 0° was equally regular. 
