Bjarne Johnsen,1 who has considered this question from the point of view of Canadian industry, gives some calculations of the cost of manufacturing alcohol from sulphite waste liquor. They rest upon data obtained by Hagglund on the basis of operations at three large pulp factories in Scandinavia, 800 gallons being taken as the quantity of liquor recovered per ton of pulp. Assuming for Canadian conditions that the costs of plant, labour, salaries, and repairs are 50 per cent. higher than in Scandinavia, and allowing 15 per cent. for depreciation and interest, the total cost of one Imperial gallon of alcohol (100 per cent.) works out at 0 22 dollar (11d.) for a factory turning out 30,000 tons of pulp, and 032 dollar (Is. 4d.) for a smaller factory with one-third of this output. By another calculation, based upon manufacturing expenses as estimated by Landmark, the cost of production works out to somewhat less than the first figure - namely, to 0.19 dollar (9 1/2d.) per Imperial gallon.

A. M. Breckler discusses this question from the American point of view, and adds some general information also, in an article on the cheap production of alcohol.2 The chief points are: sorghum juice, containing 15 per cent. of hexose sugars, would be from 0 4 to 0 6 cent per gallon with coal at the same price.

Fuel and water-supply are important considerations. Waste sulphite liquor as concentrated for fermentation contains 4 per cent. of hexose sugars, corresponding, in practice, with a yield of about 22 per cent. of alcohol. The heat of distillation per (U.S.) gallon of 80 per cent. alcohol (vol.) from such a liquid would be 126,000 B.Th.U. under the best conditions, and would probably in practice approach 180,000 B.Th.U. On this basis, 10 to 14 lb. of a good coal would be required. At a price of 3 dollars per ton for coal, the cost of the distillation would be from 1.5 to 21 cents per gallon.

In like manner, the cost of distilling 80 per cent. alcohol from

1 J. Soc. Chem. Ind., 1918, 37, 131.

2 J. Ind. Eng. Chem., 1917, 9, 612.

With starch-containing materials, where the mash requires preliminary " cooking," the number of B.Th.U. as calculated for the distillation may be multiplied by the factor 2 5. In a grain distillery the fuel required for grinding, pumping, etc., is about 50 per cent. of the total quantity used. To condense 100 gallons of 80 per cent. alcohol and cool it down to 85° F. (29° C), the quantity of water required will range from 900 gallons at 55° F. (13° C.) to 1250 gallons at 80° F. (27° C).

In general, assuming a liquid as prepared for fermentation to contain 10 per cent. of fermentable matter, the following table shows the maximum permissible cost per pound of fermentable matter for the production of alcohol at any given cost per proof gallon, allowing a yield of 85 per cent. (N.B. - U.S. "proof" = 50 per cent. alcohol by volume, and U.S. gallon = 0833 Imperial gallon).

Thus in examining whether alcohol from potatoes could compete with gasoline (petrol) as a motor fuel, suppose the price of the gasoline to be 30 cents per gallon. Assuming that absolute alcohol and gasoline give the same amount of power per gallon, the cost of the alcohol must be taken as 15 cents per proof gallon. Then from the table, the raw material must cost not more than 17 cents per lb. of fermentable material. Potatoes for alcohol contain 20 per cent. of starch = 22.2 per cent. of dextrose; so that the maximum allowable cost per lb. of potatoes is 0222 x 1.7 = 038 cent if the residue is not utilised as a feeding-stuff. Or, reckoning 0.1 cent per lb. of potatoes for the value of the residue as a feeding-stuff, the maximum that could be paid for potatoes in this case would be 048 cent per lb., or 288 cents per bushel. The average farm value of potatoes, however, was 61.4 cents per bushel during the nine years 1907-1915, and the price of gasoline per gallon in 1917 was 20 cents, not 30; so that according to these calculations potatoes in the United States, just as in this country, do not promise to be a sufficiently cheap raw material of alcohol to compete with petrol as a fuel under present conditions.