44 
DRS. W. RAMSAY AND S. YOUNG ON THE INFLUENCE OF 
The results with acetic acid and naphthalene generally agree with those obtained with 
ice ; the differences at low temperatures being greater than at high temperatures. 
Owing to the low vapour-tension of naphthalene (9 millim.) at its melting-point 
(79'2), and to the want of data regarding its vapour-tension at lower temperatures, it 
was not thought worth while to make more extended experiments. 
13. Camphor presents unusual facilities for the study of this question. Its melting- 
point is 175°; its vapour-tension at that temperature is 354 millims., and at 20° is 
1 millim. ; a great range is thus secured. 
The apparatus, however, had to be modified in order to permit the tube containing 
the thermometer which supported a block of camphor to be jacketed with a vapour, 
and also to prevent stoppage of the passage by condensation of camphor vapour. 
It is represented in the accompanying figure (fig. 3). 
Fig. 3. 
A. Block of: camphor round thermometer B, inserted in tube. 
C, D. Jacketing tube containing aniline, the vapour of which could he made to 
surround C. 
E. Condenser. 
F. Tube connected with Sprengel’s pump. 
G. Indiarubber tube, closed by screw-clip, through which air could he admitted 
to alter pressure. 
The thermometer was coated by dipping it repeatedly into melted camphor until a 
sufficiently thick layer had accumulated. The tube C was closed by an indiarubber 
cork through which the thermometer passed. The condenser E was placed in cold 
water during the experiment. 
On establishing a fair vacuum, and boiling the aniline so as to jacket the tube con¬ 
taining the camphor with aniline-vapour at 184°‘5, the temperature of the camphor 
rapidly rose, but no sublimation took place until the temperature had nearly reached 
its upper limit. The camphor then rapidly sublimed, and its temperature and the 
pressure indicated by a manometer connected with the air-pump were read. The 
pressure was then altered, and other readings taken. At very low pressures the cam¬ 
phor-vapour passed over into the condenser, which in these cases was cooled with a 
