8 TlMEHRl. 



steam and air are diathermanous, whilst ammonia 

 vapour is adiathermanous, and interferes to a very con- 

 siderable extent with heat waves. For an explanation 

 of the phenomena of temperatures in a multiple evapo- 

 rator it is more than probable that we must consider the 

 adiathermancy and varying specific heats of ammonia 

 and other gases given off under conditions of density, 

 temperature and pressure, which we know, but the cause 

 of which we are ignorant. 



For instance, going back to calaiidria tubes corroding 

 at their tops, and this taking place most aflively in the 

 third vessel, the a6lion being invariably most severe on 

 the side remote from the entrance of the vapour; these 

 are fa6ls, and reasoning from these fa6ts the following 

 conclusions present themselves : — 



(a.J The Calandrias contain two or more very distin6l 

 gases or vapours. 



(b.) These gases or vapours separate, and locate and 

 appropriate whole or parts of zones suitable to their 

 chara6lers. 



(c.J The destru6live gases are the lighter. 



fd.J The light and most destrudlive gases are given 

 off in the third vessel, where the density and vacuum is 

 the highest and the temperature the lowest. And 

 where the difference of temperature is greatest, this latter 

 (apart from a6lual observation), is one third more 

 than one would expe6l. 



(e). Different cane juice under exa6tly similar chemical 

 treatment gives off very different gases. 



With regard to paragraph (aj , the writer has not on 

 hand at the present moment an analysis of calandria 

 water; chemists and scientists tell us that these gases are 



