22 



ENCYCLOPEDIA OF PRACTICAL HORTICULTURE 



root itself, is fermentable. On this as- 

 sumption a ton of roots should produce 

 about 42 gallons of alcohol. At $5 per ton, 

 which would be a fair price with modern 

 methods of cultivation, the raw material 

 would cost about 12 or 13 cents per gal- 

 lon of alcohol. That technical difficulties 

 might arise in handling it is very pos- 

 sible, but the analytical data and cost af- 

 ford every reason for testing the value as 

 a source of alcohol. 



Potatoes — Following is the average com- 

 position of Maine potatoes, as determined 

 a few years ago in the Bureau of Chem- 

 istry: 



Per cent. 



Water 77.0 



Ash 9 



Protein 2.2 



Fiber 7 



Fat 1 



Starch 18.3 



Sugars, etc., by difference 8 



Total ^ 100.0 



Samples analyzed more recently in con- 

 nection with the work of the experimental 

 distillery were found to contain about 15 

 per cent of starch and 0.4 per cent of 

 sugars. Liquid wastes from starch fac- 

 tories in Maine were also examined, but 

 did not contain sufficient fermentable ma- 

 terial to be of value for alcohol produc- 

 tion. 



The method of working potatoes is dis- 

 cussed at length in Farmers' Bulletin 410. 

 For every per cent of starch contained 

 in potatoes they should yield about 1.6 gal- 

 lons of alcohol per ton. If the tubers con- 

 tain 16 per cent of starch, a ton should 

 yield over 25 gallons of alcohol: and if 

 they can be delivered at the distillery for 

 $5 per ton, a fair price for culls in potato- 

 growing regions, the raw material for a 

 gallon of alcohol will cost about 20 cents. 



In Germany the potato is almost the 

 only material used as a source of indus- 

 trial alcohol, not only because it offers a 

 cheap raw material, but because it is 

 highly advantageous from an agricultural 

 point of view. It undoubtedly will be 

 similarly utilized in this country in the 

 future. 



Sweet potatoes — The following average 

 data are based on work done at the South 

 Carolina station (1) and may be consid- 

 ered as representing sweet potatoes of 

 good quality: 



Per cent. 



Water 66.0 



Ash 1.0 



Protein 1.5 



Fiber 1.3 



Fat 5 



Sugars 5.5 



Starch 21.8 



Undetermined material 2.4 



Total 100.0 



These roots are seen to contain about 

 27 per cent of fermentable substances, of 

 which approximately one-fifth is sugars. 

 In storage there is a decrease in the starch 

 percentage and a corresponding increase 

 in that of sugar. 



Preliminary experiments conducted at 

 the Bureau of Chemistry indicate that the 

 sweet potato can be mashed in about the 

 same way as the common potato. Un- 

 doubtedly there will be some slight de- 

 struction of sugar on heating under pres- 

 sure, but it ought not be such as to cause 

 a serious loss. It does not appear that 

 the somewhat fibrous character of the 

 root interferes with steaming it in an 

 apparatus built for potatoes. 



A ton of sweet potatoes, containing 

 about 27 per cent of fermentable sub- 

 stances and costing $8, should yield ap- 

 proximately 38 gallons of alcohol at a 

 cost of about 21 cents a gallon for raw 

 material. 



Mannfactiire of Alcohol 

 Historical Note 



Although there are processes by which 

 alcohol may be made synthetically in the 

 laboratory, they are too complicated and 

 expensive to have any practical manu- 

 facturing value. Therefore the method 

 which has been used for many centuries, 

 namely, the distillation of fermented- 

 sugar solutions, is still employed in al- 

 cohol production. This manufacturing 

 process is very ancient, having been used 

 probably as early as 800 B. C. It seems 

 for many centuries to have been employed 



(1) South Carolina Bulletin 136. 1908, p. 11. 



