8 BULLETIN 359, U. S. DEPARTMENT OF AGRICULTURE. 



Table VII. — Average breaking strength of single threads arranged in order, for comparison 



according to grade relations. 





[With twist per inch 



as indicated by the twist 



constant.] 







Twist constant. 



Num- 

 bers of 

 yarn. 



Extra 



Ari- 

 zona. 



Fancy 



Sea 

 Island. 



Choice 

 Ari- 

 zona. 



Extra 

 choice 



Sea 

 Island. 



Good 

 Sakel- 

 laridis. 



Stand- 

 ard 

 Ari- 

 zona. 



Fully 



good 



fair 



Sakel- 



laridis. 



Medi- 

 um 

 Ari- 

 zona. 



Fair 

 Sakel- 

 laridis. 



3.80 



30's 



60's 

 60/2 

 lOO's 

 lOO's 



14.88 

 4.29 



11.54 

 2.09 

 1.77 



15.35 

 4.53 



12.02 

 2.23 

 2.02 



15.13 



3.88 

 10. So 

 2.01 

 1.82 



14.99 

 4.50 



11.43 

 2.14 

 1.92 



15.87 

 4.35 



11.91 

 2.03 

 2.00 



14.96 

 4.18 



11.85 

 2.13 

 1.94 



15.31 

 4.60 



12.25 

 2.16 



1.78 



14.54 

 4.10 



12.08 

 2.02 

 1.92 



14.93 



3.80 



4.25 



3.25 



12.01 



3.80 



1.98 



3.2.5 



1.69 









6.91 



7.23 



6.74 



7.00 



7.23 



7.01 



7.22 



6.93 



6.97 









Table No. VII gives the results obtained from a single thread- 

 testing machme. The table is arranged for comparing the different 

 yarns with the various kinds of cotton according to grade. The 

 results here seem to be somewhat in favor of the SakeUaridis-Egyptian 

 cotton, witli Sea Island coming second, but where extra choice Sea 

 Island is compared with good Sakellaridis, out of five numbers of 

 yarn produced, the Sea Island is stronger than the Sakellaridis in 

 two cases. 



The single-thread tests ^ were made more for the purpose of ascer- 

 taining the relative uniformity in the strength of the different yarns 

 than for the average breaking strength. From this point of view 

 there was no decided difference between the cottons tested. 



The tensile strength of the yarn was obtamed in the laboratory at 

 Washington by reeling off skems of 120 yards each from the various 

 grades and kinds of cotton. These skeins were placed on racks in 

 order to keep them separate and untangled. A power yarn tester 

 was used, the downward stroke of the traverse moving at the rate of 

 approximately 12 inches per minute. The humidity was kept as 

 nearly constant as possible by taking records with a sling psychrom- 

 eter every half hour and regulating the humidifier in the testmg 

 room. The desired point of relative humidity was 65 per cent. The 

 skeins were taken one at a thne in rotation from the different racks 

 and broken. They were then weighed and the results recorded. 

 This operation was repeated, usually 24 times, until the average 

 breaking strengths shown in Tables VIII and IX were ascertained. 

 From these tables it will be seen that there is no significant relation- 

 ship between the breaking strength of the different grades of Ari- 

 zona-Egyptian cotton.^ 



1 All single-thread tests were made at the New Bedford Textile School, New Bedford, Mass., by 

 William Smith, principal in charge of the carding and spinning department of this school, who also fur- 

 nished generous assistance throughout all these tests. 



2 See Bureau of Plant Industry Circular No. 110. 



