Early settlers in the Northwest had found spring wheat, with its power of rapid growth in the long sunshine of high latitudes, a better crop than winter wheat, occupying the soil for two seasons and liable to winter kill. But the spring wheat berry, although of higher nutritive value than that of winter wheat, had a flinty envelope and yielded a flour too dark in color to suit the market. A revolution in the process of milling presently reversed the places of the two flours. Milling had already advanced so far beyond the primitive separation of flour from bran by hand sifting as to segregate a residuum of coarser granules, called “middlings,” which, subjected to a second grinding, yielded a low grade flour. It had been discovered also that these middlings contained the more nutritive elements of the wheat berry, and it had been a problem how to recover them. French millers were in possession of a method for its partial solution. George H. Christian of Minneapolis had long studied on the problem, and in 1870 employed a French immigrant named La Croix to construct a rude apparatus in his mill at Minneapolis. This was the germ of the “middlings purifier,” soon developed and installed in all mills using spring wheat. Receiving middlings from the first grinding, the machine by use of sieves and air currents separated out the pure wheat granules. These were reground and “bolted” into two or more grades of flour. The first grade was put on the market as “Minnesota Patent,” and for a time commanded a price of three dollars a barrel above any other. The same principles, refined upon, have resulted in the more modern process of “gradual reduction” by means of rollers, displacing the immemorial millstones.