544 



Prof. J. Dewar. 



[June 17, 



On the sulphuric coming iu sight a small layer of bromine was seen 

 on the surface, which was surmounted by a layer of darkish red liquid, 

 about \ inch long. The pressure was about 60 atmospheres. 



On increasing the pressure to 90 atmospheres, the upper liquid 

 increased a good deal in quantity and then disappeared entirely, but 

 immediately reappeared on reducing the pressure a few atmospheres, 

 and remained permanently. 



Carbonic Acid and Camphor. 



Some small pieces of camphor were placed in the capillary part of 

 an ordinary Cailletet tube, near the end, and fused so as to adhere to 

 the sides. The tube was then filled with carbonic acid gas. 



On compressing this mixture in the pump at 12° C. the camphor 

 was seen to melt and run down the sides of the tube before the mer- 

 cury appeared in sight (in this experiment it was not observed whether 

 liquid carbonic acid had commenced to form in the tube and thus dis- 

 solve the camphor, or whether the latter was dissolved in the gas). On 

 continuing the pressure so as to almost fill the tube with liquid, two 

 distinct layers of liquid were seen, the lower one being slightly 

 cloudy, containing the dissolved camphor, the upper liquid being per- 

 fectly clear. On compressing at different temperatures up to 55° 0., 

 the lower cloudy liquid was always present, the upper layer diminish- 

 ing gradually in quantity as the temperature rose, but at 40° C. there 

 was still a slight layer on increasing the pressure to about 125 atmo- 

 spheres. 



On withdrawing the pressure very suddenly when the tube was full 

 of liquid at 50°, the sides of the tube became coated with crystallised 

 camphor, which rapidly dissolved again on increasing the pressure. 

 After doing this several times, a very small quantity of camphor was 

 seen to crystallise out, and in taking down the tube, the most of it was 

 found to have crystallised out in the top part of the reservoir near the 

 joining with the capillary part, thus allowing the mercury to get past 

 it on again increasing the pressure. 



Carbonic Acid and Camphor (second tube). 



Another tube was filled in the same way as the last (a rather larger 

 quantity of camphor being placed in the capillary part), with this 

 exception, that the carbonic acid, after being dried, was passed through 

 a tube, containing fragments of solid camphor, which were gently 

 heated, so as to fill the tube with carbonic acid gas, saturated with the 

 vapour of camphor. 



When this tube was compressed in the pump at a temperature of 

 15° C, and when the pressure reached 27" 7 atmospheres, the camphor 

 was seen to gradually melt and run down the sides of the tubes before 

 the mercury appeared in sight. 



