84 PRESERVATION OF FOOD BY REFRIGERATION ; 
is impossible, and in order to realise it, we will endeavour 
to follow the action of the process of cooling as it takes 
place in such a substance as meat. In the first place let us 
look at the composition of meat. The table 1 (Appendix 
A) gives the constituents of an average fat bullock 
and sheep, and from it we find that 27 parts are 
bone, 36 parts mineral matter, 779 parts nitrogenous 
substances, 27°5 parts fatty matter, and 36 parts water. 
Above a temperature of, say, 95°, the 27°5 parts of 
fatty matter are in a more or less liquid state, but 
as we are not concerned with a temperature of 95°, but 
with one of 32°, we have only to consider the 36 parts of 
water as being in the fluid state. All the other 64 parts 
being then solid, their power of conduction remains un- 
altered, either above or below 32° Fah. 
By turning to table 7 (page 23), which shows the very 
feeble conducting power of water when prevented from 
circulating, we are led to believe that it would act in a 
similar manner if locked up in an infinite number of small 
cells having walls of a feebly-conducting substance, and 
that in the case of meat, in which the watery constituents 
form portions of the contents of cells, the conduction of 
heat will not exceed that due to the water in the condition 
above named. 
Inasmuch as water is the only part of the meat that 
would be altered in condition by the abstraction of heat, 
any difference in the conducting power of meat frozen and 
unfrozen would be due to the different conducting power of 
water and ice. According to MM. Despretz and Newman, 
the conducting power of ice and water stand in the pro- 
portion of ‘0057 to ‘O117 respectively, as compared with 
copper at 17108, or in the proportion of 1: 2 nearly, so that 
whatever the conducting power of meat may be at any 
temperature above freezing, the conductivity, when the 
temperature is reduced below 32° Fah., will be reduced, so 
far as the effect due to the water only is concerned, in the 
proportion of 2:1. The 64 per cent. of solid substance is 
not affected in its conducting power by the fact of the 
thermometer showing a temperature of over or under 32° 
Fah., as it is solid in both cases. 
