THE BRISTOL PERIOD 73 



I then spent a year at the Strassburg University and, while 

 there, took lessons in glass-blowing from a professional glass- 

 blower. In Bristol, after making a Wollaston's cryophorus for 

 my evening lectures, it occurred to me that by altering the size 

 of one bulb and fusing in a glass rod ending below in a knob about 

 the centre of the smaller bulb, one might get a block of ice sus- 

 pended in this bulb and Carnelley's experiment might be much 

 more easily carried out than by his rather cumbrous method. 



The result was quite satisfactory and I showed the experiment 

 to the Owens College Chemical Society, and described the 

 apparatus in the Chemical News, 47, 104 (1883), mentioning at 

 the same time that Prof. Ramsay and I proposed to investigate 

 the question of the temperature of the ice by inserting a thermo- 

 meter in each bulb. The thermometer in each case was passed 

 through a tube of suitable size, a wired indiarubber tube serving 

 to keep the thermometer in position and to make the cryophorus 

 airtight. With this apparatus we were able to prove that the 

 ice does not become hot even when the temperature to which 

 it is subjected is very high, and also that the temperature of the 

 ice falls when the pressure is lowered by cooling the larger bulb 

 by means of a freezing mixture. A fair estimate of the pressure 

 was afforded by the temperature in the interior of the cooled 

 bulb, knowing the vapour pressures of ice. A narrow side hole, 

 provided with an indiarubber tube and a screw-clip, was added, 

 and through this air could be admitted so as to raise the pressure 

 very slightly. 



The results obtained were very encouraging, and the next step 

 was to make direct measurements of pressure by connecting 

 the cryophorus with an air-pump and manometer ; and it after- 

 wards occurred to us that the method might be used for liquids 

 by covering the bulb of the thermometer with cotton-wool and 

 admitting fresh liquid, as required, to moisten the cotton-wool 

 by means of a vertical tube provided above with a stopcock (or 

 indiarubber tube and clip) and reservoir, and drawn out sideways 



