Cellulose, which constitutes about 50 per cent, of wood, can be partially resolved into dextrose and other sugars by treatment with acids under pressure. After neutralisation of the acid, the sugars, or the greater part of them, can be fermented with yeast, and the resulting alcohol separated by distillation. On the ground of economy, sawdust or other wood waste is the material employed.
The process was developed on a laboratory scale by Classen at the University of Aix-la-Chapelle, and was subsequently tried as a manufacturing experiment at Chicago. It was there found that about 300 lb. of fermentable sugars could be obtained from one ton of pine sawdust. Following these demonstrations, a company (The Classen Lignin Co.) was formed to work the process com mercially, and four plants were erected in America for the purpose.
So far as the production of alcohol is concerned, success has been met with, undoubtedly. Thus a plant established at Georgetown, S. Carolina, was reported in 1911 to have run for more than a year, producing upwards of 2,000 gallons of alcohol per day.2 Nevertheless, it appears that by 1914 only one of the four plants remained in operation, and the process was still regarded as in an experimental stage.3 The industry has also been tried experimentally in this country, but apparently was not able to compete successfully with the established methods.
Though simple in principle, the process presents various technical difficulties in operation. Since 1914, however, improvements have evidently been made in working it in the United States. According to one authority, a method is now in operation at Fullerton, Louisiana, whereby a yield of 86 gallons of 95 per cent, alcohol is obtained per cord of sawdust or common wood waste. Taking pine wood at 920 lb. per cord of 128 cubic feet, this yield works out to 21 gallons per ton. It is stated that the quality of the alcohol is very good, much of it being used in perfumery.
The output of this plant is said to be 2,000 gallons per day. The Georgetown distillery, mentioned above, was later (1918) turning out 2.500 gallons. On account of the demand for alcohol in making munitions of war, the process was no doubt remunerative at that time, but it remains to be seen whether in normal circumstances alcohol so produced will be able to hold its own against that from molasses and other sources.
According to Mr. C. F. Cross, the difficulties have been so far overcome as to allow of alcohol being produced on the large scale at a very low cost. Under the most favourable conditions, however, the yield of alcohol actually obtained represents only about 8 per cent, of the cellulose content of the wood.1 Larger yields, however, are possible; and wood waste must be considered a very important raw material for the potential production of alcohol in well-timbered countries.
Considerable quantities of alcohol are now being made from the waste liquor produced in the manufacture of wood pulp by the “sulphite" process. This waste liquor contains from 1 1/2 to 2 per cent, of fermentable sugars, arising from the action of sulphites on the wood; and alcohol is produced from these sugars by neutralising the liquor, fermenting, and distilling it. In Norway, two plants are now (1918) in operation for this purpose, whilst in Sweden four are working, and three more are being erected. About one million gallons of alcohol per annum are being turned out by the four Swedish instalments. In Germany thirteen factories have been built for the same purpose, and probably are now in actual working. There are also two plants in the United States, and one in Switzerland.2 To develop the manufacture of this “sulphite spirit" in Sweden, it has been proposed officially that the production and sale of denatured alcohol for the propulsion of motors and for other technical purposes shall be reserved as far as practicable to the sulphite spirit factories. Further, these establishments are to have the exclusive right of denaturing their alcohol with benzol.
Alcohol from wood usually contains an appreciable quantity of methyl alcohol, and in this country such a product could only be used for making methylated spirit or other variety of denatured alcohol, not for making beverages.
Peat has been advocated as a possible source of cheap alcohol II
the biochemical agents: enzymss; malt; yeast.