BROwx : TiiK ca:mpanilk. 91 



al)oul the ^iaiit which is to be raised from the dead is vain and 

 empty. In liei,<;lU it was two hundred and eighty-four Vene- 

 tian feet, or ninety-eight metres. But there is no metre to tell 

 us how high are piled the traditions, the memories, the events 

 on which the bronze angel set up in 15 13 and renew^ed in 1822 

 spread its gilded wings to the breath of the winds and the roll 

 of the centuries. Soon shall we see, once more, ivhcrc it zcas 

 and as it 7vas, this majestic tower. Upon its pinnacle we 

 shall behold the gilded angel of bygone years ; and from its 

 belfry as of old will peal once more over city and lagoon those 

 bells whose silence now saddens everv Venetian soul." 



THEORY OF FREEZING MIXTUREvS. 



Abstract of talk before the Institute, 

 BY T. CIIALKLEY PALMER. 



A sattirated solution of a salt in a liquid may often be 

 cooled below the point at which the salt ordinarily separates, 

 without causing solidification. But when a minute fragment 

 is dropped into this so-called supersaturated solution rapid 

 crystallization occurs. A delicate thermometer will indicate, 

 at such a time, the disengagement of large amounts of heat. 

 This heat is the energy which, so long as the salt continues in 

 soluti(m, keeps the molecules apart. When the molecules rush 

 together, and so lose the bulk of this independent motion, the 

 motion becomes sensible heat. Similarly, in order that the 

 particles or molecules of a solid may part company and spread 

 themselves abroad ' through a liquid, heat or some form of 

 energy must become latent — or, more scientifically, it must 

 cease to exist as sensible heat and be converted into motion. 

 The process of solution calls for the expenditure of energy. If 

 the energy is not forthcoming from the chemical reaction of 

 the salt and the solvent, it must come from the solution itself 

 or its surroundings. Hence the lowering of temperature when 

 solution takes place. The amount of energy so converted 



