SCIENCE AND INDUSTRY. 
factors which can be expected to influence oil yield and quality, and 
the influence of which should be studied, are set forth below:— 
(a) Size of shale particles treated. 
(b) Thickness of charge in the retort. 
(c) Rate of rise of temperature of the charge. 
(d) Maximum temperature to which shale is submitted. | 
(e) Time of contact with and maximum temperature to which 
vapours are submitted. 
(f) Effect of steam and other vapours and gases. 
(g) Pressure under which retorting takes place. 
If greatest economic returns are to be obtained from oil-shale opera- 
tions, the effect of such factors as these should be determined. - 
Figs. 3 and 4 show, respectively, the retorting and laboratory equip- 
ment established at Boulder in connexion with the above-mentioned 
investigation. ; 
Tuer SuHare O1rs. 
Once the oil is produced, it must be studied to determine its 
refinability. The high refining loss incurred in Scotch operations has 
been noted, and efforts should be made, of course, to keep this figure 
to a minimum in the refining process. New processes of refining and 
treating may be worked out when the oils produced are thoroughly 
studied and tried out in commercial operations. The Bureau of Mines, 
at its Salt Lake City Station, in co-operation with the State of Utah, 
is studying the oils produced from various shales and by various pro- 
cesses, correlating its work in this regard with the co-operative work in 
Colorado. . ; 
All American shale oils thus far studied by the Bureau are highly . 
unsaturated and contain a considerable amount of nitrogen bases. 
Some of the unsaturated compounds can probably be allowed to remain 
in the finished products, but others polymerize and deposit gums and 
resins which must be removed in refining. The use of steam in Scotch 
retorts seems to prevent the occurrence of nitrogen bases in the oil to 
a large extent. It seems that ordinary methods of refining petroleum 
will have to be modified for shale oil, and such modification can be the 
result only of thorough study of the oils themselves, 
Particular attention is directed to the high loss incurred in refining 
Scotch shale oil. The refining loss, as has been noted, amounts to about 28 
per cent. of the crude treated. Thus, although average Scotch shale yields 
about 24.5 gallons of erude oil to the ton, only about 20 gallons of this is 
marketed. As compared with this high loss, the average loss in straight 
run refining of petroleum in American practice does not exceed 34 or 4 
per cent. If the shale oils thus far examined by the Bureau of Mines 
are a fair indication of what can be expected from American: shales 
in commercial operations, apparently the loss in refining them by Seotch 
methods would amount to nearly twice the loss in refining Scotch shale 
oils. If ordinary petroleum-refining methods are used, probably the 
loss would be still larger. 
754 
