ON ICE-MAKING AND ICE- MACHINES. 
275- 
2. The derivate of the Napierian logarithm representing the 
ratio between vapour-tension and temperature, is constant for 
all liquids, when they are compared under the same circum- 
stances of pressure and temperature. 
3. The latent heat of all liquids referred to one and the same 
pressure, multiplied by the molecular weight referred to a uni- 
form temperature, gives a constant product. 
4. For all liquids, the difference between the latent heat at 
any two temperatures, multiplied by the molecular weight, is a 
constant number. 
5. The latent heat of every liquid is a multiple of its specific 
heat. 
It would be entering too much into detail to give the method 
by which these very important conclusions have been arrived at, 
but it maybe of interest to some readers to know that an article 
on the subject was published by M. Pictet in the last volume of 
the u Philosophical Magazine.” 
