Mar., 1918
T H E J O U R N A L O F I N D U S T R I A L A N D E,VGINEERING C H E M I S T R Y
DISTINGUISHING MANILA F R O M ALL OTHER “HARD”
ROPE FIBERS By CHARLBSE. SWETT Received December 4, 1917
I n the rope industry fibers are classed as “soft,” hemp, jute, linen, cotton, etc., and “hard,” as manila (musa), sisal (agave), maguey, New Zealand ( P h o r mizcm tenax) and others. In general, t h e hard fibers are lignified. Among the soft fibers jute also is a lignified fiber, b u t its physical characteristics place it beside hemp . The two hard fibers of preeminent importance are manila and sisal. The distinction between manila and sisal is not easy, except by a practical rope maker and not always b y him, especially when they occur together in rope. When it is desired t o estimate the amounts of t h e two present in a given rope t h e microscope has t o be used. The cross-sections are characteristic but not in all cases satisfactory. For instance, sisal from East Africa is sufficiently different from manila t o enable one t o separate them, b u t sisal from Yucatan (henequin) is not always enough different t o make it possible t o say how much may be present. The sections are not easy t o make and when made may contain thousands of fibers. When it is considered t h a t t h e field under magnification t o 2 0 0 diameters is of t h e order of one millimeter and t h a t a rope of 2 or 3 in. of cross-section may have t o be examined it will be understood t h a t some method for differentiating these fibers other t h a n t h e employment of t h e microscope would be of great use. Such a method has been worked out in this laboratory and is here described in some detail. If t h e sample is treated with a solution of bleaching powder acidulated=with acetic acid, then with ammonia, manila takes a russet-brown color. All other hard fibers t u r n cherry-red. Thus it becomes possible t o distinguish manila from all t h e others, which is t h e matter of chief importance. SOLUTIONS REQUIRED
t o pour down a strand t o remove most of the spinning oil. 2 . BLEACHING POWDER SOLUTION-A clear solution of chloride of lime, containing about j per cent of available chlorine, acidulated with acetic acid (30 cc. of bleaching solution and 2 cc. glacial acetic acid). Acidulation with an acid stronger t h a n acetic will not answer, for example, hydrochloric acid will give no test. 3. WATER t o rinse after t h e above. 4. A L C O H O L t o remove water. I.
ETHER
j. STRONG AMMONIA. P R E L I M I N A R Y E X A M I N A T I O N OB THE SAMPLE
Remove most of t h e oil b y pouring ether down t h e strand. Wave through t h e air for a minute or two t o remove most of t h e ether; immerse one end of t h e sample in t h e acidulated bleach solution for 2 0 sec.; rinse first with water, then with alcohol and t h e n immerse in ammonia. Manila will instantly turn brown.
Sisal, S e w Zealand, istle, Mauritius, maguey will assume a cherry-red. When so applied the test is somewhat fugitive, the red color degrading in t h e course of a few minutes so t h a t it may not be possible t o pick out t h e different colored fibers from the strand. As applied i t enables one t o say whether t h e sample is all manila, all nonmanila or a mixture. This is all t h a t is required in many instances. When it becomes necessary t o estimate the percentages of manila and non-manila the procedure is as follows: Apply t h e test as before but instead of immersing the fibers in ammonia in t h e last operation, suspend t h e treated end of t h e strand above t h e ammonia for a minute or SO. As t h u s practiced the manila does not assume t h e brown color as rapidly, b u t a t t h e end of 2 or 3 min. t h e color develops and is permanent. The cherry-red of t h e non-manila fibers remains for hours and a separation may be made by picking out t h e red or the brown. A reading glass is of assistance. When the separation is made as above it is desirable t o take the two differently colored strands and apply the test as first described, i. e . , by treating t h e hitherto untreated ends with ether, immersing in bleach acetic solution, rinsing with water and then immersing in ammonia. This serves as a check and as t h e separation will be closely approximate as a result of t h e fuming test, t h e few fibers which may show up as wrongly placed can be removed with ease. One desiring t o practice this test should first work on samples of known origin. With practice i t seems t o be possible t o estimate the manila content of a rope down t o a single fiber. As t h e test is so quickly applied i t is t h e writer’s practice t o take less t h a n a strand for treatment and then go through t h e sample taking perhaps 2 0 or 30 fibers at a time, The difference between the red and the brown is most evident at t h e end of 3 or 4 min. after fuming with t h e ammonia. The bleach solution made with one part of chloride of lime and seven parts of water, then filtered, may be kept in a stoppered amber bottle away from t h e light for a long time. When some is t o be used i t should be poured from t h e stock solution a n d acidulated with the acetic acid for present use. Throw away when t h e tests are done. It will not keep in an acidulated condition. Chlorine water will not serve, neither will iodine solution or bromine water; nor will any acid tried answer so well as acetic. Too much emphasis cannot be placed on t h e fact t h a t hydrochloric or other strong acid is not suitable t o replace acetic acid as used in this test. This reiteration is made because, notwithstanding specific instructions, two competent chemists have assumed t h a t because t h e test failed with hydrochloric acid there was nothing in it. I n neither case were the directions followed and when attention was called t o this fact no trouble was experienced in securing the appearances described. LABORATORY OF ARTHUR D. LITTLE, INC. CAMBRIDGE, MASS.
