78 
PROFESSOR W. RAMSAY AND DR. S. YOUNG 
extended 12 millims. below the bulb and about 30 millims. above it. The hydrate 
was therefore undoubtedly heated above its usual melting-point without melting. 
§ 14. The third experiment began with a temperature of 52° and a pressure of 
9'2 millims. Air was then admitted, so as to raise the pressure to 24 millims., while 
the temperature was rising. The registered temperature was 53°. More air was 
admitted from time to time, and the following readings were taken :— 
Pressures . . . . 40'3 53 - 0 53'0 60'6 
Temperatures. . . 52‘0 50‘0 49‘0 49'0 (melting). 
As soon as the substance began to melt, air was removed by pumping. When the 
pressure was reduced to 40*3 millims., the temperature being 48 , 4°, the substance 
entirely solidified, and after further reduction of pressure to 23 millims., the tempera¬ 
ture rose to 51°. Air was then admitted, so as to raise the pressure to 61 - 6 millims., 
when the hydrate melted. It is noticeable from this experiment, that admission of 
air, to increase the pressure, lowered the temperature, and its removal raised the 
temperature; and that the substance melted only when the temperature had fallen 
below its ordinary melting-point; and that the pressure at which fusion occurred was 
in this, and in other similar cases, about 60 millims. 
vj 15. Confirmation of the above results was obtained with a fourth series. 
Pressure. 
Temperature. 
Pressure. 
Temperature. 
Pressure 
Temperature. 
millims. 
O 
millims. 
O 
millims. 
O 
7'4 
50-0 
410 
56-0 
42-0 
50-0 
7'5 
52-0 
40-0 
53'7 
falling 
53'0 
7-6 
54-0 
47'5 
53-0 
5? 
54 - 0 
7-7 
5-5 - 0 
59‘6 
52-0 
55-0 
81 
56'0 
59-6 
51-0 
56’0 
8-1 
57-0 
59 - 6 
50-7 
Substance solid ; air admitted. 
Melting ; air removed by 
pumping. 
Pressure increased to 64 millims. 
Substance melted. 
§ 16. In the fifth series, to ascertain if the chloral hydrate would melt if the 
pressure were high, and the temperature raised towards the melting-point, the 
substance was heated at a pressure of 24 millims. It began to melt when the tem¬ 
perature registered was 24°. It was evident that the heat had not had time to 
penetrate to the interior. The substance was cooled, and again heated at a pressure 
of I 6'5 millims. The hydrate melted only when in contact with the stem of the 
thermometer, where it was evidently heated by conduction. These observations were 
confirmed by a sixth experiment, in which the pressure was 25 millims., and the 
temperature registered, when fusion began, 37°. After cooling and lowering the 
pressure to 15‘2 millims., the temperature rose on again heating to 55°, without the 
