198 JOURNAL OF FORESTRY 



yield of 45 per cent of pulp, about 2.5 per cent of the dry wood is re- 

 covered as alcohol. The results obtained by Krause^ show that man- 

 nose constitutes about 60 per cent of the total fermentable sugars in 

 sulphite liquor. The various woods examined contain sufficient mannan 

 alone to furnish 2 to 4 per cent alcohol so that considerable mannose 

 is evidently destroyed during the cooking process. It is plain, how- 

 ever, that mannan must be considered the chief source of the ethyl 

 alcohol. 



By the hydrolysis of white spruce Kressman^° obtained 6.8 to 8.;> 

 per cent of absolute alcohol. This species contains 7.12 per cent mannan 

 from which it is theoretically possible to obtain 3.5 per cent alcohol. It 

 is difficult, however, from available data to determine how much alco- 

 hol is derived from the mannose. Mannose" is apparently as stable 

 when heated with acids as dextrose, but it is probable that considerable 

 mannose is destroyed during the cooking since all the mannan would 

 be hydrolyzed at the beginning of the reaction. Yeasts that ferment 

 dextrose will usually ferment mannose equally well, but exceptions 

 occur. 



EXPERIMENTAL 



The method of determining mannan was the following: The wood 

 cut into sawdust was so ground as to pass' through a 40-mesh sieve. 

 A portion was removed for determining moisture. Ten grams of the 

 fine material with 150 c.c. of hydrochloric acid sp. gr. 1.025 were placed 

 in an Erlenmeyer flask connected with a reflux condenser and boiled 

 3^ hours. The contents were then filtered into a 500 c.c. flask, and 

 the sawdust washed back into the Erlenmeyer with about 100 c.c. of 

 distilled water. The sawdust was then digested a short time over a 

 Bunsen burner, and again filtered. This method of extraction was 

 continued until the total filtrate amounted to 500 c.c. The solution 

 was then transferred to an 800 c.c. beaker, neutralized with 10 per 

 cent NaOH, rendered slightly acid with acetic acid, and evaporated 

 on the steam bath over night to 150 c.c. The solution was again fil- 

 tered to remove humus matter, the filter being washed with a little 

 cold water. A mixture of 10 c.c. of phenylhydrazine and 20 c.c. of 

 water, rendered acid with glacial acetic acid, was added to the filtrate 

 contained in a 200 c.c. Erlenmeyer. The flask with frequent shaking 

 was allowed to stand two hours. The precipitate of mannose phenyl- 

 hydrazone was collected in a weighed alundum or Gooch crucible 

 washed with cold water, then with acetone to remove resinous im- 



9Chem. Ind., 29 (1901), 217. 



i» Jour. Ind. Eng. Chem., 7 (1915), 920. 



" Fischer and Hirschberger Ber.. 22 (1889), 365. 



