10 



BULLETIN 839, U. S. DEPARTMENT OF AGRICULTURE. 



Apparently, sifting or thorough mixing of the flour a number of 

 times has little appreciable effect upon the offal count obtained. 



NUMBER OF SLIDES COUNTED. 



In practice, two slides, or at most three, from the sample of flour 

 have been used as the basis for judgment as to the character of the 

 product as far as the offal material was concerned, and the question 

 might very properly be asked if that number is sufficient. In order 

 to test out this point, 12 slides were prepared from the same bulk 

 sample of flour. Two counts on each slide were made of the bran 

 particles and hairs by each of two analysts. The results obtained are 

 recorded in Table 7. 



Table 7. — Counts on 12 slides. 



Slide des- 

 ignation. 



Analyst. 



Count 

 No. 



Bran 

 parti- 

 cles. 



Hairs. 



Slide des- 

 ignation. 



Analyst. 



Count 

 No. 



Bran 

 parti- 

 cles. 



Hairs. 



A 



Keenan 



....do 



Lyons 



. ..do 



1 



2 

 1 

 2 

 1 

 2 

 1 

 2 

 1 

 2 

 1 

 2 

 1 

 2 

 1 

 2 

 1 

 2 

 1 

 2 

 1 

 2 

 1 

 2 



21 

 22 

 20 

 22 

 24 

 23 

 19 

 23 

 23 

 31 

 34 

 33 

 33 

 30 

 31 

 35 

 24 

 22 

 23 

 26 

 31 

 29 

 29 

 30 



76 

 75 



78 

 77 

 54 

 53 

 52 

 56 

 55 

 60 

 59 

 53 

 77 

 81 

 84 

 82 

 79 

 79 

 82 

 78 

 64 

 65 

 70 

 66 



G 



Keenan 



do 



2 



38 

 32 

 35 

 40 

 37 

 24 

 38 

 40 

 26 

 44 

 44 

 42 

 39 

 38 

 34 

 41 

 32 

 30 

 33 

 37 

 32 

 36 

 42 

 39 



1 64 



A 



G 



, 57 



A 



G 



Lyons 



' ' '61 



A 



G 



61 



B 



Keenan 



do 



H 



Keenan 



do 



: ' ; 61 



B 



H 



47 



B 



do 



H 



Lyons 



.. ..do 



56 



B 



H 



61 



c 



do 



I 



Keenan 



do 



74 



c 



I 



67 



c 



do 



I 



Lyons 



do 



67 



C 



I 



72 



D 



Keenan 



. do 



J 



Keenan 



do 



50 



D 



J 



55 



D 



do 



J 



Lyons 



do 



48 



D 



J 



56 



E 



Keenan . 



. do 



K 



do 



63 



E 



K 



60 



E 



Lyons 



do 



K 



Lyons 



do 



68 



E 



K 



71 



F 



Keenan 



do 



L 



Keenan 



do 



- - 47 



F 



L 



49 



F 



Lyons 



.....do 



L Lyons 



L do 



47 



F 



51 













From the data in Table 7 it is possible to average Keenan's first 

 count on slide A with each count made by him on each of the other 

 slides. By averaging the slides by two, 20 is found to be the lowest 

 average and 43 the highest average for bran particles, considering 

 Keenan's results only. If the average of counts for three slides 

 instead of two is to be taken as the basis for final judgment of the 

 product, it is apparent that 22 is the average of the three lowest 

 results and 40 the average of the three highest (Keenan's results on 

 bran particles). Taking the average of the counts on each of four 

 slides gives an average minimum count of 22 and an average maximum 

 count of 39. Table 8, based on data obtained from Table 7, has 

 been prepared to show the results of such methods of grouping. 



