86 PHYSIOLOGICAL ACTIVITIES 



the alcohol, though molds replace them in some countries 

 ("sake" and "arrak" from rice). 



Under ordinary conditions the carbohydrate is never com- 

 pletely fermented, since the accumulation of the product- 

 acid— stops the reaction. If the acid is neutralized by the 

 addition of an alkali— calcium or magnesium carbonate is 

 best— then the sugar may all be split up. Where such fer- 

 mentation occurs under natural conditions the products 

 are further split up, partly by molds and partly by acid- 

 destroying bacteria into simpler acids and eventually to 

 carbon dioxide and water, so that the end-products of the 

 complete fermentation of carbohydrate material in nature 

 are carbon dioxide, hydrogen, marsh gas and water. 



In all of these fermentations the bacteria are utilizing the 

 carbon both as building material and for oxidation, and the 

 fermentations are incidental to this use. As a rule, the acid- 

 forming bacteria can withstand a higher concentration of 

 acid than the other bacteria that would utilize the same 

 material and in a short time crowd out their competitors 

 or inhibit their growth, and thus have better conditions for 

 their own existence, though finally their growth is also 

 checked by the acid. 



The best example in the world of the commercial applica- 

 tion of "fermentation of carbohydrates" is afforded by the 

 plants of the Commercial Solvents Corporation at Terre 

 Haute, Ind. and Peoria, 111. Fig. 61 shows a few of their 

 "fermenters," the capacity of each of which is 50,000 gallons. 

 There are 96 of these at Peoria and 52 at Terre Haute. Cheap 

 corn, much of which would otherwise be waste, is used as 

 raw material to the extent of 30,000 bushels per day. The 

 organism which does the fermenting is Clostridium aceto- 

 butylicum Weizman. The mash used as food for the bac- 

 terium is 8 per cent corn in water. Forty thousands gallons 

 are filled into each fermenter. The products recovered are 

 butyl alcohol, acetone, ethyl alcohol, CO2 and H2. The 

 most desirable of these is the butyl alcohol used so largely in 

 "Duco" and similar lacquers for automobiles. The concen- 

 tration of the liquid products at the end of two and a half 

 days fermentation is 2| per cent of which 60 per cent is butyl 



