TEMPERATURE OF VAPOUR FROM BOILING SALINE SOLUTIONS. 221 



into the matter more closely, it is clear that the temper- 

 ature of the inner wall of the jacket must have been higher 

 than the temperature registered by the thermometor c. 

 Although the leading tubes u and t were lagged to prevent 

 condensation the jacket itself was not lagged. There must 

 have been very considerable condensation and reduction 

 of temperature on the outer wall of the jacket, in fact the 

 conditions were those of air condensation of the vapour. 

 The temperature shown by the thermometerc would depend, 

 under these circumstances, upon its position relatively to 

 the inner and outer walls of the jacket, and there could 

 easily be a considerable difference in the temperature of 

 these walls with a vapour at 130° and the outer wall un- 

 tagged. The thermometer in the diagram is shown midway 

 between the two walls, so that it is quite possible that the 

 temperature of the inner wall of the jacket was consider- 

 ably higher than that shown by the thermometer c, and 

 that consequently heat may have been supplied by the 

 jacket although the thermometer c was lower than a. 

 Another drawback to Sakurai's experiments is that the 

 vapour for the jacket was not obtained by boiling a pure 

 liquid. Either acetic acid diluted with water, or amyl 

 alcohol containing a little of the lower alcohols, was used. 

 This was unfortunate, because the temperature of this 

 vapour must have risen gradually as the liquid was distilled. 



Although this rise is shown in the experiments quoted, 

 there is no data to indicate how much the temperature of 

 the thermometer c was lower than the temperature of 

 the vapour as it left the flask from which it was distilled. 

 In the case of the amyl alcohol it can be assumed, from 

 the fact that it contained a little of the lower alcohols, 

 that it was derived from fusel oil. The main constituent 

 of amyl alcohol from this source, viz. isobutyl carbinol, boils 

 at 131*4°. It is also known that amyl alcohol from fusel 

 oil distils principally between 128° -132°, so that looking 



