POSSIBILITIES OF COOLING-, CHILLING. AND FREEZING. 
719 
the aid of irrigation immense stretches of the less heavily watered 
interior may become the centres of large populations with ample 
supplies of food materials of the best quality at their command. 
Such, in brief, are some of the better prospects for Australian 
agriculture made possible through the agency of chilling and freezing. 
The appliances available are also being simplified, and the cost 
reduced to an extent which warrants the belief that ere long every 
branch of business in need of the help which colder temperature 
supplies will have this aid at command. 
The agencies employed for the production of cold are ammonia, 
carbonic acid, air, and ether. Other agencies are used, but those 
mentioned are most in favour for practical purposes, and generally in 
the order named. So marked have been the improvements made in 
the machinery used for producing cold, and the skilled mechanics in 
charge have such control of the delicate materials upon which the 
machines operate, and so well are the power and peculiarities of such 
substances as ammonia, carbonic acid, &c., understood* that accidents 
to either the person or machine are few, and seldom serious. 
When we consider that a very large portion of the work of making 
cold is carried on at sea during long voyages through the most trying 
parts of the tropics, there is every reason for confidence that absolute 
control over temperature — for the production of cold to chill or freeze 
as may be needed, and for maintaining the temperature at any point 
which has the effect desired upon the cargo — is only a question of 
time, and that thawing can be carried out in such manner as to restore 
the meat, fish, or fruit to its normal condition before chilling. 
My own experiments and tests, as showing the effects of cold 
upon substances which are already among our exports, may be of 
interest and use at this stage. 
The water contents of all the substances are most immediately 
acted on by cold. Assuming that water is at its most dense or solid 
form at a temperature of 39° F., when lowered beyond 39° water 
increases in bulk, and we generate snow and ice, both of which are 
more bulky and lighter than water at 39°. Then, as we raise the 
temperature, the bulk of water again increases until it vaporises into 
steam. 
All this seems simple enough. The facts and conditions are easily 
understood, and conclusions appear feasible that the watery contents 
of meat, fruit, fish, and other substances can be so controlled by chilling 
from 45° to 32°, or by freezing below 32°, that substances can 
be preserved and carried in such a semi-solid form, and below the 
range at which bacterial life is active, and that the preserving of the 
substances will be absoluteand certain when so treated. But experience 
has not given such satisfactory results. While as a whole the busi- 
ness of transporting in the chilled-frozen state has been carried on 
with such creditable results as are nothing short of wonderful, dis- 
appointments and losses have occurred, in the face of all the care and 
skill exercised. It may be safe for me to add that no two cargoes 
have been carried with identical results, although the same care was 
taken throughout ; and much the same results have followed experi- 
ments made with fruits, meat, &c., both in chilling or freezing tempera- 
tures. It seems to me, therefore, that at this stage those who have 
opportunity to make tests can do efficient practical service for the 
