Page:Foods and their adulteration; origin, manufacture, and composition of food products; description of common adulterations, food standards, and national food laws and regulations (IA foodstheiradulte02wile).pdf/330

 results: Without nitrogen—yield of tubers, 16,781 pounds per acre; yield of starch, 3,277 pounds per acre. With nitrogen—yield of tubers, 19,629 pounds per acre; yield of starch, 3,856 pounds per acre.

The following varieties of potatoes are considered in Germany the best for the manufacture of alcohol: Wohltman, Silesia, Agricultural Union, Athenena, Prince Bismarck, Richter's Imperator, and Maercker. The latest consular report on the potato as a source of alcohol in Germany shows the following yields per acre and percentages of starch:

Kilograms. Percent. Professor Wohltman,                     3,420           16.3 Iduna,                                  2,845           16.4 Topaz,                                  3,260           17.3 Sas,                                    3,990           18.3 Leo,                                    4,120           17.0 Richter's Imperator,                    4,760           15.4 Silesia,                                3,675           16.3 Professor Maercker,                     4,280           14.5

Use of the Potato.—In addition to its value as human food the potato has other economical relations. It is used in many countries almost exclusively in the production of starch for the laundry and for general domestic uses.

The potato is not very extensively used for starch production in the United States except in the state of Maine and perhaps in one or two other localities. The starch of the potato has a particular value for use in the textile industry in the sizing of cloth. Practically all of the potato starch which is produced in the United States is devoted to that purpose, and for this reason it brings a higher price than the ordinary starch made of Indian corn.

Technique of the Production of Starch from Potatoes.—There is scarcely any manufacturing process which is more simple in its method than the manufacture of starch from potatoes. The process consists simply in the rasping or grinding of the potato to a fine pulp, which is afterward placed upon sieves in a thin layer and sprinkled with water which detaches the starch granules from the pulp matter, carries them through the sieve, and thus separates them from the fibrous portion.

It will be interesting to the general reader, on account of the importance of this product, to give a brief description of the method employed and the results obtained.

Potato Starch.—In this country potato starch is manufactured chiefly in Maine, Wisconsin, and Colorado. The factories are of a very primitive type, the machinery consisting of a rasper constructed usually by wrapping a wooden cylinder with sheet-iron punctured so that the ragged edges of the hole are on the exterior surface as shown in Fig. 41. Water is added at the time of