UTAH ACADEMY OF SCIENCES 235 
Taking up the purposes enumerated: we find that 
the first two are important from engineering and thermo- 
dynamic viewpoints. Reducing the temperature of the 
hot spent shale just before its discharge from the retort 
simplifies the problem of designing the mechanical dis- 
charge devices and also allows a better recovery of heat 
than could be obtained by the use of any practical form 
of heat exchange device to recover and utilize the heat 
from the spent shale before its discharge from the retort. 
The design of the Scotch retort is such that the heat recov- 
ered from the hot spent shale is almost wholly utilized in 
the retorting process. 
The third purpose enumerated: the formation of 
water-gas from the fixed carbon remaining in the shale, 
may make the use of steam, or possibly air, advantageous. 
Present available data indicate that the uncondensible 
gases recovered during the retorting process where steam 
or air is not used in the retort, will usually not furnish 
enough heat when burned as fuel to carry on the distil- 
lation process. The volume of gas recovered during the 
retorting probably depends upon the-nature and charac- 
ter of the shale undergoing distillation and the conditions 
of retorting. Different volumes of gas, due to dissimilar 
pyrolytic conditions, are usually recovered from the same 
shale undergoing distillation in different retorts. It seems 
probable that shale retorting processes recovering large 
quantities of gas, during dry destructive distillation, do 
so at the expense of the quantity and quality of recovered 
oil. A minimum non-condensible gas production shoul 
make toward a better grade of crude oil and especially 
will this be true in retorts where the hydrocarbon vapors 
are subjected to undue decomposition before condensa- 
tion. The formation of large quantities of inflammable 
uncondensible hydrocarbon gases is usually an indication 
of excessive decomposition or cracking of the heavier 
hydrocarbons of the shale oil. 
The use of steam or air in the retort will, by the for- 
mation of carbon monoxide and hydrogen, increase the 
quantity of combustible gases recovered during the retort- 
ing process, and not at the expense or decomposition of 
the hydrocarbons. 
