10 BULLETIN 983, U. S. DEPARTMENT OF AGRICULTURE. 
lining after every two or three operations proved a source of great 
delay and expense. 
Ewen and Tomlinson, who were associated with the Classen process, 
began experimenting along new lines to overcome the difficulties 
that prevented the old process from becoming a commercial success. 
The results of their researches (United States Patent No. 763472) 
were: (1) The time of hydrolysis was shortened from 6 hours to 45 
minutes; (2) the treated wood waste was obtained in a form which 
could be quickly and efficiently extracted; (3) a digester was devised 
which was not affected by the process; (4) the quantity of acid em- 
ployed was reduced; (5) a large and uniform yield of fermentable 
sugars was obtained from the wood. 
In general, these results were accomplished in the following way: 
Instead of adding an aqueous solution of sulphur dioxide to the saw- 
dust and afterwards heating this large volume of water, steam was 
used as a source of both heat and moisture, and the sulphur dioxide 
was introduced into the digester in a gaseous form. This method 
shortened the heating period and also decreased the amount of wood 
that was reduced to a powdered condition, thereby permitting a more 
complete extraction. 
On October 26, 1909, Ewen and Tomlinson were granted a patent 
protecting the process of producing fermentable sugars from lig- 
nocellulose (United States Patent No. 938308). This patent shows 
that they had given up the use of sulphur dioxide, both gaseous and 
in solution, and were employing sulphuric acid as the inverting or 
catalytic agent. A study of the patent reveals the fact that the ratio 
of water and acid to dry wood which they used was practically the 
same as in the method patented bySimonsen and referred to above. 
Ewen and Tomlinson, who were then the engineers and technical 
advisers of the Standard Alcohol Co., erected a plant at Georgetown, 
S. C., 24 for the production of ethyl alcohol from sawmill waste. This 
plant was later acquired by the E. I. du Pont de Nemours Powder 
Co., which operated it intermittently until the early part of 1913. 
A fire then destroyed the main sawmill of the Atlantic Coast Lumber 
Corporation, and the alcohol plant was not operated until the summer 
of 1914, when the sawmill had been rebuilt. The alcohol plant has 
been operated successfully since that time under the Ewen and 
Tomlinson patents. 
Several years ago the Classen Chemical Co. interested western 
capital in the erection of a plant at Port Hadlock, Wash., on Puget 
Sound, for the production of ethyl alcohol and cattle food from saw- 
dust obtained from mills at Seattle, Tacoma, Everett, Anacortes, and 
Port Blakely. The plant was equipped with six digesters of the 
24 For a description, see R. von Demuth, Zeit. fur ang. Chemie, 26, 786; also G. Foth, Chemiker Zeitung, 
37, 1221, 1297. 
