XXXII. NORMAN SELFE. 
THe MACHINERY EMPLOYED ror ARTIFICAL 
REFRIGERATION anp ICE MAKING. 
By Norman SELFE, M. Inst. C.E., M.I.M.E., &e. 
(Read before the Engineering Section of the Royal Society of N.S. Wales, 
July 15, 1896.) 
Ow1na to the very great increase, which has lately come about in 
the exportation of our food products to Europe, few branches of 
mechanical engineering are of so much importance to Australian 
trade as the design and construction of the machinery used for 
producing low temperatures, popularly known as “ Freezing 
Machines.” 
HISTORICAL. 
Over three hundred years are supposed to have elapsed since a 
was first discovered that artificial cold is produced by the chemical 
action which takes place when certain salts are dissolved, but it 
is not known how far back the system of making ice has been 
practised which is still in use in India, where shallow trays of 
porous material are filled with water and exposed to the night air, 
when the heat is abstracted by natural evaporation. The use of 
frigorific mixtures for the abstraction of heat (many forms of 
which are still set out in works on chemistry) was known as far 
back as the year 1607, and the most common combination, that 
of ice and salt (which is said to have been used by Fahrenheit in 
1762, when he placed the freezing point of water at 32° as the 
limit of negative temperature) is still in every day use for such 
purposes as ice cream freezing. The production of cold by what 
may be termed mechanical means—that is by the use of a refriger 
ating machine, as distinguished from chemical action—-is of much 
more recent date. A Dr. Cullen is said to have made a machine 
for evaporating water under a vacuum in 1755, and Lavoisier 
experimented with ether in France, but the next important steps 
appear to come well into the present century. In the year 1810, 
