tory scale. Attempts at commercial operation, how- 

 ever; developed fresh obstacles and led to the aban- 

 donment of the process. The well known German 

 chemist, Alexander Classen, patented during the 

 year 1900, 1902 and 1903 various modifications of 

 the general process of producing sugars and alcohol 

 by treatment of comminuted wood with strong acids 

 under heat. Subsequently several plants were built 

 in this country for carrying out one or another of these 

 modifications. In none of them were any substantial 

 amounts of alcohol produced, and the Classen process 

 must be regarded as commercially inoperative. It 

 remained for Ewen and Tomlinson to overcome the fun- 

 damental technical difficulties underlying all these at- 

 tempts and to put forward the first process capable 

 of large scale production of ethyl alcohol from wood. 



The Ewen and Tomlinson process is essentially one 

 for producing fermentable sugars. The fermentation 

 of these sugars, once produced, may be carried out 

 and the alcohol recovered in any distillery by the 

 usual methods. It is my belief that the process af- 

 fords the cheapest known method for producing these 

 sugars and that it therefore is ultimately destined to 

 become an important if not the most important 

 source of industrial alcohol. 



In carrying out the process, hogged wood waste, 

 usually containing about 50 per cent of water, is loaded 

 into a rotary digester holding about 7 cords and hav- 

 ing a protective and heat-insulating lining. Sulfuric 

 acid in relatively small amount is sprayed upon the 

 wood and then steam is admitted to the digester. The 

 critical temperature is reached as quickly as possible 

 and the reaction is then extremely rapid if not indeed 

 nearly instantaneous. Pains are therefore taken to 

 reduce the pressure immediately and to empty the 

 digester of its contents as promptly as may be. About 

 25 per cent of the weight of the wood is converted to 

 reducing sugars, not all of which are fermentable. 



The cooked material, which is not unlike coarse 

 coffee grounds in appearance, is transferred by con- 

 veyors to a diffusion battery or other extraction ap- 

 paratus in which the sugars are dissolved out. The 

 spent chips go to a continuous press for removal of 

 excess water and are then available as fuel. The ex- 

 tracted juice is neutralized with lime and is then ready 

 for fermentation. The concentrated slop from the 

 stills finds use as cattle feed and is about equivalent 

 to molasses for that purpose. 



(6) 



