14 



GRAHAM FLOTJR. 



in the composition of true Graham than are sometimes shown by 

 mixtures of flour with other mill products such as bran or other 

 offal. 



PHYSICAL EXAMINATION. 



Since Graham flour is supposed to be wheat ground into meal 

 without bolting, it was thought that a mechanical separation of the 

 flour by sifting, and a macroscopic and chemical examination of the 

 several portions would show whether the flour was an imitation or a 

 true product. 



Graham flour, when ground either on rolls or on a stone mill, is 

 composed of particles of all sizes, ranging from the chopped bran to 

 impalpable powder, while the general run of imitation Graham 

 flours is composed of bran together with flour which generally is of 

 a very even granulation; therefore all that is necessary to be done in 



i | the case of most of the samples 



of Graham or imitation Graham 

 flour is to pass them through a se- 

 ries of sieves, weigh the portions 

 remaining on each sieve, and 

 make a macroscopic examination 

 of the products. For the purpose 

 of making the mechanical separa- 



2O 



40 



/O9 (FTME M/DDL/NGS) 



tions, a bolting frame such as is 

 attached to an experimental mill 

 was used. This frame held four 

 sieves (in the case of the first few 

 samples analyzed only three sieves 

 were used, namely, a 20, 30, and 

 109), giving five separations; that 

 is, those portions remaining on the four sieves and the portion going 

 through the finest sieve. The four sieves used ranged in fineness as 

 follows: 1st, a 20-mesh wire; 2d, a 40-mesh silk bolting cloth; 3d, 

 a 70-mesh silk bolting cloth; 4th, a 109-mesh silk bolting cloth, 

 equivalent to a No. 10 standard silk. 



Several preliminary experiments were made to determine the 

 length of time required to have all the material well sifted. It was 

 found that 5 minutes was not long enough, and so 10 minutes was 

 adopted as the proper time to run each sample. All the material 

 that can pass the 109-mesh sieve passes through in 10 minutes at 

 160 gyrations per minute. This portion is called flour. The accom- 

 panying diagram shows a cross section of such a sieve. 



A macroscopic examination of the products of separation is of the 

 greatest importance, since in this way one may often detect or 

 determine whether the bran is an added product or not. The appear- 



