Cotto n cut in a Wiley mill to pass a 20-mesh scr ee n was ground in a vibrator y ball mill similar to one t hat has been used in German y and H olland. Con tamination of the cotton was practically elimin ated by using a chromium-plated hardened steel jar and chl'omium all oy balls. The jar holder is held by a slip rin g instead of being bolted in place. The jar and holder automatically rotate slowly on t h eir axis, and t his motion co unteracts t he ten dency of t he cotton in t he jar to settle and grind nonuniforml}'. The jar is cooled by blowing air over it and becomes bare ly warm to t he to uch.Five grams of dried cotton disintegrated rapidly during t he first 15 minutes of milling. The largest particles remaining after 30 minutes of milling were about 10 microns in major dimension, and t here was little redu ction of the maximum size wit h longer milling. Cuprammonium fluidity of t he cotton increased rapidly in the first hour of milling and more gradua lly th er eafter. The carboxyl co ntent of t h e cotton increased very slowly with time of milling and reached only abo ut 0.2 percent after 8 hours . The moist ure r egain of t he cotton at 55-percent relative humidity at 21 0 C increased rapidly during t he first hour of milling, from 7.1 to 12.5 percent, and t h en r emained practically constant . X-ray diffraction meas urements showed t hat the cellulose wa co nverted almost completely to t he amorphous form in 30 minu tes, and t hat it underwe nt litt le chan ge t hereafter.The powdercd cotton obtained from the vibratory ball mill was mulled in mineral oil. The resulting pa ste was injected into rock salt cells fo r infrared absorp t ion measurement s. The powder workcd reasonably well in this procedu I'C, disti nctly better t han t he coarse powders obtained by other method of grindin g. No significant differences were found i n the infrared absorption of a rege nerated cellulose film, the cotto n ground in a Wiley mill to 200 mesh, and cotton ground in t he vibratory ball mill for period s of tim e fr om 15 minutcs t o 8 hours.It is concluded that the vibratory ball mill, as mOdified, redu ces cotton, rapidly a nd completely, to a ver y fin e powder, suitable for infrared t rans mi ssion m easure ments and other purposes. Milling results in practically negli gible ox idation of t he cellulose, but in a marked decrease in degree of polymerization , and in almost complete conversion of cr ystalline to amorphous cellulose. The Problemby these m ethods contained much coarse ma teri al. A m ethod that would reduce the entire sample to a finely divided state, without contamination and with a minimum of ch emical change, wa desired.The first problem arising in the attempt to apply infrared spectropho tometry to cotton cellulose was to prepare the cotton in a form sui table for introduction into the b eam of the spectrophotometer. Microspectrophotometers applicable to single cotton fibers were not available at the time the work was started , though promisin g instruments are now being developed [1 , 2, 3, ...

A quantitative method for the evaluation of the color of manila-rope fiber was developed at the request of the Cordage Institute and the Cordage Committee of the Federal Specifications Board. Spectral reflection and colorimetric measurements showed that the variations in color correspond chiefly to variations in luminous reflectance. The reflectance at wave length 500 nut, which is obtainable with relatively simple apparatus, was found to be sufficient for the grading of the fiber for color. The fibers in a cross section of the rope are cut into lengths of 1.5 to 2.5 mm, mixed, extracted with petroleum ether, and spread out to give a smooth surface. The ratio of the reflectance of this surface to that of the usual white standard magnesium oxide surface for light of wave length 500 mjt (when the two surfaces are in effect equally illuminated at an angle of approximately 45°and viewed in a line approximately perpendicular to the surfaces) multiplied by 100 gives the numerical value, "Becker value", for the rope. The Becker value of the commercial ropes tested varied from 29.0 to 51.0. Before removal of the lubricant the values were from 8 to 16 units lower. The value obtained for a single specimen taken from a coil of rope was found to be within two units of the average value for several specimens. The method is prescribed in the latest revision of the Federal specification for manila rope.

The " brown-line" reaction on cellulosic ma terials at t he boundary between areas wet with water and dry areas has now been found to be an example of a general phenom enon . Other fib ers and liquids participate in oxidat.ion react ions at wet-dry interfaces. Examples of t he r eactions arc given , t he conditions necessary for t hem are demon strated , and the nature of t he reactions is disc ussed .

Yarns ranging from low tenacity and high elongation to high tenacity and low elongation were broken by impact loading and by static loading. The energy required to break each yarn under impact loading, "impact energy," and under static loading, "static energy" ; the elonga tion at break; and the tenacity were measured or calculated. The results show that the impact energy to rupture can, in general, be estimated from the static energy. The impact energy greatly exceeded the static value for yarns of low elonga tion. For yarns breaking above an elongation of about 50%, the impact energy was about equal to the static energy, except for two yarns having an elongation of over 500%, where it was less than the static value. Yarns having a very high elongation when tested at 70°F and 65% relative humidity had greatly reduced elongation when dried for 120 hrs. at 190°F and tested immediately. The elongation was still further reduced when the dried yarns were cooled for 1 hr. at — 40°F and tested immediately. These findings have a bearing on the selection of yarns for the construction of safety belts, safety ropes, and certain aeronautical textiles which may be subjected to impact loading over a wide range of temperatures.

The rate at which silk, particularly weighted silk, will deteriorate on exposure to light, heat, and moist air cannot be predicted simply from the amount of weighting or other substances present on the silk. A laboratory test which will indicate the relative stability of silks is needed.The aging, as revealed by changes in breaking strength, of a variety of silk and weighted-silk cloths when stored in the dark, when exposed to the daylight received through a north window (natural aging), or to the radiation from thc glass-enclosed carbon-arc lamp under controlled conditions of temperature and relative humidity of the atmosphere (accelerated aging) was studied.Data on the accelerated aging of some typical silk dress fabrics were obtained.