IMPROVEMENTS IN PRESERVING FOOD, AND IN THE MEANS AND APPARATUS EMPLOYED THEREFOR."
Year: 1877

page_text: PROVISIONAL SPECIFICATION left by Robert Little at the Office of the
Commissioners of Patents on the 16th February 1877. Partly a communi-
cation from abroad by Dugald Little, residing at Sydney, New South Wales.
ROBERT LITTLE, of Greenock, in the County of Renfrew, North Britain, Mer-
chant. "IMPROVEMENTS IN PRESERVING FOOD, AND IN THE MEANS AND APPARATUS
EMPLOYED THEREFOR." Partly a communication from abroad by Dugald Little,
residing at Sydney, New South Wales.
This Invention has reference to the preservation of animal, vegetable, and fruit
food during transit by sea or land, or in storehouses, and whether placed in stationary
or portable close compartments, chambers, or vessels within the transporting ships,
vehicles, or stores, natural cold-maintaining and artificial cold-producing or refri-
gerating appliances being used for this purpose in a new or improved manner, and
by a new arrangement of apparatus or mechanism, which is more simple, efficient,
and economical, both as to. the stowing and removal of the food material, and the
construction, management, maintenance, and action of the apparatus than the
methods heretofore employed for the purpose; and the nature and novelty of the
Invention consist all as follows:-In having the compartments or other stationary
or portable chambers in which the food is placed for preservation by preference
insulated from the external air or surroundings, so as not to transmit heat to the
inside of the chambers or cold from them, and when convenient or where ice or
snow is easily or cheaply obtained to make provision for their application and use
next the outer surface of the chambers, and inside the outer enveloping wood, straw,
sawdust, or other insulating material used. The flesh, fish, or other food is hung or
packed loosely without touching, preferably with laths or other equivalent between
them to effect this, so that the drying and refrigerating air may freely circulate all
round the surface of the articles to be preserved to dry and cool them while in the
chambers into which they are placed, through doors fitted in them, so as to be
easily and quickly opened, and shut air-tight, or nearly so, and insulated, as the
other outer sides or surfaces are, all substantially as many ordinary ice houses,-
chambers, and boxes are insulated by envelopes of non-conducting material, so as
to keep these chambers and the food within them as cold as possible; in addition
to which, by further improvements, the coldness of the interior of these chambers
and their contents is also kept up or maintained during the transit against loss by

page_text: outward conduction or radiation. This is effected by the use of an improved
general construction or arrangement of air-compressing cylinders or engines and
coolers or condensers for the compressing and cooling of the air in its compressed
state, which is afterwards forced or led from the said coolers, or an air pressure
receiver in connection with them, through pipes or ducts, so as to be admitted
under high pressure and expanded intermittently or in a regular stream into the
before-mentioned preserving chambers to keep or maintain the air in these chambers
at the cold or reduced temperature required to preserve the food in good sound
condition.
The compressing engines or cylinders may be of any of the ordinary constructions
used for compressing or drawing and forcing air, such as those used for motive-
power purposes in driving coal-getting machines, or for the production of cold by
expansion of compressed air, such as that of Kirk's well-known engine or refrigerating
machine for the production of cold by the expansion of air; and the condensers or
coolers may consist of strong cased vessels of any ordinary construction capable of
sustaining the pressure of air within the cooling spaces, and giving sufficient cooling
surface for the water or other cooling medium to circulate over or through such as
the surface condensers used for marine engines, or those used for the distillation of
spirits, with water-circulating pumps for drawing and forcing the cooling water
through the outer case of the cooler; and the air, either before entering the com-
pressing engine or on leaving it might be passed through a vessel with chloride of
calcium, sulphuric acid, or other equivalent, which would absorb all the moisture in
and dry the air before entering the preserving chambers, where by its expansion it
dries and cools the air and food contained therein. These close preserving chambers
may be fitted at their upper sides with ventilators or light loaded valves, for the
escape of a portion of the warmer air therefrom from time to time, to make room
for the fresh supply of cold, dry, expanded air from the cooling or compression
chambers; or, otherwise, when it is desired to have a greater amount of expansion
or current of air in or through these preserving chambers, the waste or hot air may
be drawn off or exhausted from these by suction pumps or other equivalent, the
injection of the high-pressed air on the one hand, and the drawing off of the warm
air on the other, causing a greater current of the cooling and drying air.
way the same pumps which compressed or forced the air might be made to draw off
the waste air circulating pumps, in which case some of the forms of rotary pumps or
blowers might be used.
In this
The essential feature of the Invention consists in preserving the food by com-
pressing (and when necessary drying) the air, and cooling it while in a state of
compression before allowing it to escape or expand into the preserving chambers,
and the amount of cold required to maintain the air in the chambers at the low
temperature necessary would be regulated by the difference of pressure and the heat
abstracted from the while under pressure, and to which it was expanded within
the chamber; thus in tropical latitudes the air would require to be subjected to
much higher pressures than in the more temperate latitudes to maintain the food at
the constant low temperature required for its preservation.
When desired fanners or other blowers or agitators may be used within the cold
food-preserving chambers, or close to them with connecting orifices, to cause the
circulation of the air through these chambers.