REPORT OF THE CHEMIST. 



89 



As regards variety, the Dent, as would be expected, averages heavier 

 per hundred kernels than the Flint, and with it also lie the extremes 

 of weight, 64 grains per hundred and thirteen. In southern latitudes the 

 Dent kernels are ranch heavier than in the northern, between the Mid- 

 dle States and the Southern there being a difference of ten grains per 

 hundred. In New England Dent corn is hardly ever raised, but the 

 Flint which is raised nearly equals in weight the Dent of Pennsylvania. 

 Conversely, Flint only is raised in the North and Northwest, and there 

 excels in weight. 



The heaviest corn comes from Virginia, North Carolina, Kentucky, 

 and Tennessee, and from the last-named State the heaviest single speci- 

 mens. The weight per hundred kernels in the larger corn-producing 

 States averages about thirty-two grams (or an ounce), Missouri being 

 somewhat higher — forty grams. 



CHEMISTRY OF THE ROLLER MILLING PROCESS OF GRADUAL RE- 

 DUCTION. 



It is the object of milling to reduce the floury portion of the wheat- 

 grain to the finest possible form without injuring its physical condition, 

 and at the same time with complete exclusion of portions of the bran 

 and germ, and such refuse products as would injure its baking qualities 

 and color. An examination of the structure of the grain will enable us 

 to understand the difficulties to be met and the way in which the dif- 

 ferent products which have been analyzed are obtained. 



If a blade of wheat were much thickened and the two halves then 

 folded back upon themselves a transverse section of it would represent 

 a similar section of the grain; that is to say, the two lobes would meet, 

 forming what is known in the grain as the crease within which would 

 be inclosed and hidden a portion of the outer covering. This explains 

 how difficult it is in preparing the wheat for milling to remove all the 

 foreign matter which this crease contains. On the exterior of the grain 

 there is found toward one end a collection of hair, and at the other end 

 appears the embryo, or germ. A longitudinal section shows botli of 

 these undesirable additions to the floury matter of the grain. Aside 

 from its exterior appearance the wheat-grain is essentially an embryo, 

 the germ, together with a supply of food, the endosperm or floury mat- 

 ter, surrounded by several membranes or coats of greater or less im- 

 portance. On the exterior is the first membrane, or cuticle, a very thin 

 coating, easily removed by rubbing. Next follows a more important, 

 because thicker, portion of the outer covering, consisting of two layers 

 of cellular tissue, the epicarp and endocarp. These three membranes 

 together form the outer covering of the grain, and from one of them, the 

 epicarp, spring the hairs which are found on one end. These envelopes 

 are colorless and very light, constituting only from 3 to 3J per cent, of 

 the whole, and are more or less easily removed by friction. From an 

 examination of a section of the grain, it is seen that within tbe crease 

 this is of course impossible, so that while the preparation of the wheat 

 for milling may remove the hairs and much of the cuticle and dirt it 

 cannot completely free it from them. It is this inherent difficulty that 

 the roller mills attempt to overcome by splitting the grain along the 

 crease and afterwards cleaning it with brushes. 



Under these outer coverings are three membranes, known as the testa 

 or episperm, the tegmen, and the embryous envelope. The testa is a com- 

 pact affair, and carries the coloring matter of the bran. The tegmen is 



