268 THE BOOK' OP WHEAT 



until the introduction of the "new* process about 1870. Durin 

 the time of Evans, wheat was cleaned with rolling screens an 

 blast fans. About the middle of the nineteenth century smut 

 ters were introduced, and a little later, separators, by means o 

 which a more thorough system of wheat cleaning became es 

 tablished. 



"Low" Milling. Before 1850, the millstones in the Unite 

 States were run at a comparatively low speed, and the grindin 

 was slow. By this date the milling industry had assumed sue 

 commercial importance that it was necessary to increase th 

 speed of the stones in order to get the work done. From 185 

 to 1875, hard, low grinding was the rule, and the prime objec 

 was to make the largest possible percentage of flour at the firs 

 grinding. The change in process, due to greater speed, in 

 creased the output and improved its quality, ' ' the outcome bein 

 a white, soft flour that met with favor in all he leading market 

 of the world where American winter wheat flours were har 

 died." By this process, however, it was impossible to get th 

 flour entirely free from contamination, and some of the bra 

 always remained. There were two parts to this old process, re 

 ducing the wheat to flour by passing it through a run of stones 

 and bolting the resulting material in order to separate the flou 

 from the bran and other undesirable parts of the kernel. Th 

 percentage of flour obtained by this single grinding depende 

 on four things: (1) The dress of the millstone; (2) the fac 

 of grinding surface; (3) the balancing of upper or runne 

 stones; and (4) the speed of the runner. As there was but on 

 grinding, the making of middlings was avoided as much as pos 

 sible. By this method of milling, some of the bran was pul 

 verized so that it could not be separated from the flour. Thi 

 gave the flour a darker color, and caused it to gather mor 

 moisture, which injured its keeping qualities, especially in mois 

 or hot climates. 



"High" Milling was the next step in advance. In this th 

 speed of the stones was again decreased, and they were set fa 

 apart. This advance was made possible by the middlings puri 

 fier, which was not invented in the United States much prio 

 to 1870, although its principle had long been known and applie 

 in Europe. It was a machine for separating the dust, fluffy ma 

 terial, particles of bran, and the flour, from the middlings. I 



