36 



Cap+. A. C. Egerton on the Vapour Pressure 



been employed in this work, and on the whole the latter has 

 proved the more satisfactory. 



It is a matter of some difficulty to maintain fairly high 

 temperatures constant over long periods of time. Vapour 



Fig. 1. 



m 

 M 



Vacuum 



baths and baths of high boiling liquids were both found 

 unsuitable for various reasons above 200°. Below this point, 

 a very satisfactory oil-thermostat electrically heated and 

 controlled was used. Above this temperature, an electrically 

 heated air-bath was employed. It was controlled electrically 



