Aug. 19, 1918 
Influence of Humidity on Wool Fiber 
287 
In these experiments and all subsequent work the temperature was 
kept at 70° F., the humidity only being changed. The breaking strengths 
of the 200 fibers were determined on each sample, first at a humidity of 
40, and later at a humidity of 70 per cent. The results of this work 
are shown in Table I. 
TABrn I —Breaking strength of wool fibers at two humidities 
Sample 
: No. 
Breed. 
Relative humidity, 40 per cent. 
Relative humidity, 70 per cent. 
Average of— 
Variation 
between 
zoo and 
200. 
Average of— 
Variation 
between 
106 and 
200. 
100. 
200. 
zoo. 
200. 
99 1 
99 1 
994 
994 
996 
996 
997 
997 
Rambouillet.... 
do . 
Dgm. 
70. 82 
71. 26 
149- 49 
177. 11 
169. 86 
187. 81 
148. 14 
132.22 
Dgm. 
71.04 
Per cent. 
0.62 
Dgm. 
63. 14 
62. 22 
ISO- 74 
154. 86 
182. 00 
175- 40 
130*44 
131.01 
Dgm. 
62.68 
Per cent . 
I* 50 
Oxford.. 
do . 
163. 3° 
I S- 59 
152. 80 
2.65 
Cotswold. 
do . . 
178. 80 
9- S 6 
178. 70 
3-63 
Dorset. 
do . 
140.18 
10.74 
130- 73 
0.44 
An examination of Table I, shows that with the increasing of the 
humidity the breaking strength of the fibers decreases. It will also be 
noted that the percentage variation between the average breaking 
strengths of each hundred fibers reaches in one case practically 16 per 
cent. Had a larger number of fibers been broken, it is probable that the 
extreme variations between hundreds would have been even greater. 
Determining the breaking strength of the fibers under controlled 
conditions of temperature and humidity is more accurate than under 
ordinary room conditions; yet the wide variations among the sizes of 
the individual fibers makes it quite impossible to obtain a small per¬ 
centage variation between the means of each hundred fibers tested 
without taking into consideration the diameter of the fibers. An at¬ 
tempt was made to measure the diameter of the fibers in the testing 
machine by means of a microscope which could be moved horizontally 
or vertically by means of a screw adjustment. The work was found 
very slow and tedious, and it appeared that the fibers did not break 
at the smallest diameter. The fact that wool fibers are very irregular 
in shape renders the measurements taken from one side of the fiber 
very inaccurate. If a microscope can be constructed to view the wool 
fiber from two different angles at the same cross section, there may be 
obtained much more accurate results by use of this instrument. It 
seems that this condition may be obtained by a proper adjustment of 
mirrors, but to the writer’s knowledge no such adjustment has ever 
been tried. 
