8 BULLETIN 839, U. S. DEPARTMENT OF AGRICULTURE. 



slides for the same day and averaging the three results to determine 

 the analyst's daily variation. This is calculated for each analyst. 

 The ultimate daily variation is the average of the daily variation of 

 the two analysts computed for each day. The daily variation for 

 each analyst is shown in Table 4. 



'Table 4. — Daily variation for each analyst. 





Variation. 



Bran particles. 



Hairs. 



Slide. 



Jan. 7, 

 1918. 



Jan. 8, 

 1918. 



Jan. 9, 

 1918. 



Jan. 7, 

 1918. 



Jan. 8, 

 1918. 



Jan. 9, 

 1918. 



A 



Keenan. 



89 

 60 



84 



77 



108 

 83 

 88 

 93 



85 



79 

 54 

 63 

 65 



98 

 81 

 86 

 88 



76 



81 

 51 

 68 

 66 



105 



77 

 86 

 86 



76 



61 

 59 

 68 

 62 



55 



61 

 59 

 58 



60 



67 

 51 

 67 

 61 



55 

 53 

 62 

 56 



63 



65 



B 





59 



c. . 





68 







64 



A 



Lyons. 



54 



B 





55 



c. . 





63 







57 







60 









The results in Table 4 seem to indicate that on January 7, 1918, 

 there was a tendency to count higher on bran particles than on the 

 other days. It is believed, however, that this was in whole or in part 

 due to the clearing action of the glycerin employed to preserve the 

 slides for counting on subsequent days, which tended to make the 

 identification of the bran particles more difficult after the first day. 



SLIDE VARIATION DUE TO LIMITS OF ACCURATE WEIGHING OF THE TEST PORTION 



OF FLOUR. 



In order to determine the absolute variation between the slides, 

 it is evident that an average must be obtained from which the personal 

 variations and the daily variations have been eliminated as far as 

 possible. This is accomplished by computing for each slide the aver- 

 age of all counts made on bran particles, and also making a similar 

 computation for the hair count (Table 5). 



Table 5. — Counts of bran particles and hairs on slides. 



Bran particles. 



Hairs. 



Slide A. 



Slide B. 



Slide C. 



Slide A. 



Slide B. 



Slide C 



89 



60 



84 



61 



59 



68 



79 



54 



63 



67 



51 



67 



81 



51 



68 



65 



59 



68 



108 



83 



88 



55 



61 



59 



98 



81 



86 



55 



53 



62 



105 



77 



86 



54 



55 



63 



193 



167 



179 



159 



156 



164 



1 Average slide count. 



