330 
PROFESSOR W. RAMSAY AND DR. S. YOUNG 
that the views which we have already expressed regarding alcohol and ether are 
substantiated ; there is no tendency towards the formation of complex molecules at 
low temperatures. 
This research is not so complete as the former two. We have made no attempt to 
determine the compressibility of the liquid. The cause of this omission is the very 
high pressure exerted by the vapour of methyl - alcohol at high temperatures. 
During these experiments we lost a volume-tube and a gauge by bursting; and, as 
the labour involved in replacing them was very great, we did not choose to risk 
further breakage. 
O 
The approximate critical pressure of methyl-alcohol is 59,700, the approximate 
temperature 240°, and the approximate volume 3'683 cub. centims. It is notice¬ 
able here that the difference in temperature between the boiling-points of methyl- and 
ethyl-alcohols is by no means the same as the difference between their critical 
temperatures. 
In Plate 14 the relations between pressure, temperature, and volume for saturated 
and unsaturated vapour are shown ; the orthothermic constants for the liquid are also 
given. The small diagram shows these relations between the pressures 1600 millims. 
and 60,000 millims. The critical isothermal is also given. The large diagram 
represents the higher temperatures observed ; the circles are actual experimental 
points. 
Plate 15 shows the densities, compared with hydrogen, of the saturated and 
unsaturated vapour mapped against pressure. It is here noticeable that the density 
of the saturated vapour becomes normal at low pressures and corresponding low 
temperatures. 
Plate 16 shows the orthobaric densities of the liquid and vapour mapped against 
temperature, and their approach towards identity at the critical point. 
Plate 17 gives the vapour-densities of the saturated vapour, and the heats of 
vaporisation, mapped against temperature. Again the rapid increase of density and 
the rapid decrease of latent heat as the critical point is approached are noticeable. 
Addendum. 
(Added July 28, 1887 ) 
The value of such work as the foregoing evidently depends on the purity ol the 
substance employed ; and, as it appears that our paper is deficient in this proof ve 
adduce further evidence of the purity of the sample ol methyl-alcohol employed in 
experiments on its thermal constants. 
The proofs submitted are :— 
1. Constancy of boiling-point. 
