76 PRESERVATION OF FOOD BY REFRIGERATION ; 
be suppressed in proportion as the space is occupied by 
radiants or recipients, that is, by bodies which are emitting 
heat, or bodies that are absorbing it. 
The following diagram (plate II., fig 6) will illustrate the 
effect produced in a chilling room as ordinarily constructed, 
and will show that the radiation from a large number of 
the bodies is suppressed, except to the floor or ceiling, 
thereby cutting off a considerable proportion of radiative 
power and causing the heat of the bodies to be retained 
longer. 
In the chilling of meat this is a most serious drawback, as 
it gives time for the germs of decomposition to get fairly 
established, and much mischief is caused by the delay. 
In the case of B, which is one of a number of hot bodies 
placed in an enclosure at a low temperature for the purpose 
of being cooled, we see that rays of radiant heat from any 
part of its surface outside the line, C D, will strike the walls, 
W W, and be by them absorbed. 
The walls, W W, being at a very much lower temperature 
than B do not radiate back to the body the same amount of 
heat as received, and the temperature of B falls in conse- 
quence. But in the case of rays proceeding from B towards 
A, the radiation from A and the surrounding bodies being 
nearly the same as that of B, there is az exchange of heat, 
but not much loss, and consequently B’s temperature is only 
slightly lowered by radiation from the surface facing A. 
The bodies A, and those in similar positions, being sur- 
rounded by others at nearly the same temperature, do not 
lose heat in the direction of the walls, and their rate of cool- 
ing will be much slower, as far as radiation is concerned, 
than B. 
It should also be particularly noted that, as air is trans- 
parent to radiant heat (see pg. 11), a very small proportion 
of the radiation proceeding from the bodies to be cooled 
will be directly absorbed by it, and of this small proportion 
by far the larger quantity is undoubtedly absorbed by the 
vapour suspended therein. The radiation is received by 
the walls and is by them given up by contact to the cold 
air. Not only is the heat radiating from the bodies to be 
cooled (the radiants) carried away by the air in contact with 
the surface of the walls, but there is also the flow of heat 
