270 
ON ICE-MAKING AND ICE-MACHINES. 
by w. n. hartley, f.r.s.e. 
T HE resolution of all forms of energy into heat, the continual 
passage of heat through solids, liquids, and gases, and its 
tendency to become equally distributed through all matter, are 
now recognized as facts ; hence the inevitable conclusion that 
finally all substances in the solar system, if not in the universe* 
will ultimately arrive at one common temperature. Mechanical 
motion, electricity, chemical action, all other forms of energy 
which at present are sources of heat, will be completely exhausted. 
Man, by his use of machines, is hastening this end of all things, 
and this indeed by the production of low as well as of high 
temperatures. 
An economical means of freezing water is a fruitful source of 
profit at the present time, for the manufacture of ice serves not 
only the purpose of enhancing our bodily comfort in summer, 
hut also for rapidly cooling large volumes of liquid, as in the 
operation of brewing and other industrial processes, and for the 
better preservation of animal food in seasons and climates which 
hasten putrefactive changes. 
The difficulty experienced in freezing water is due to the very 
large amount of heat it must lose, firstly, in being lowered to the 
temperature of 32° F., and secondly in being changed from 
liquid water at 32° F. to solid ice at the same temperature. The 
first quantity is called its specific heat, and the second is its 
latent heat. These quantities are greater for water than for any 
other substance, hence the cooling power of ice is greater for 
any given temperature than that of any other body, and the 
cooling power of water is greater than that of any gas or liquid. 
Faraday calculated that the heat absorbed during the conversion 
of a cube of solid ice measuring three feet in the length of one 
side, into liquid water without undergoing any rise of tempera- 
ture, would require the combustion of a bushel of coals for its 
artificial production. 
It is evident from these statements that, in order to cool a 
