INDUSTRIA L A S D ENGINEERING CHEMISTRY
December, 1929
11-Tetramethylthiuram disulfide (3 per cent) as a vulcanizing agent causes rather low percentages of deterioration in ozone and sunlight, and gires fairly flat aging curves. 12-Mineral rubber (24 per cent) causes a smaller percentage deterioration than 4 per cent except at the critical elongation of about 10 per cent. 13-Paraffin (I per cent) causes pretty bad deterioration in ozone but provides some protection in sunlight.
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14-Added antioxidant does not change the shape of the ozone- or sunlight-aging curves but may lessen the amount of deterioration. 15-Two antioxidants may give comparable results in both oven and bomb, but quite different results in ozone and sunlight. 16-Synthetic rubber gives a characteristic ozone-aging curve.
Mothproofing’ M . G. Minaeff and J. H. Wright LABORATORIES OF THE LARVEXCORPORATION, 882 THIRD AYE., BROOKLYN, N.E‘.
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The process of mothproofing with formulas based The old method of moth on silicofluorides has been described and the results control with naphthalene or ing or controlling the demonstrated. It has been shown that wool possesses c a m p h o r and the modern clothes moth and rea great affinity to silicofluorides, and therefore these fumigation method are based lated insects is of such vast chemicals can be applied from dilute solutions. Owing on gaseous penetration. The importance that it has in reto these properties, mothproofing with silicofluoride new mothproofing compounds cent years received extensive formulas is much more effective and durable than with are applied to the fabric in study by the technical laborasodium fluoride formulas. t h e l i q u i d form. With all t o r i e s of both federal and Different methods of determining the efficiency of chemicals of the fumigas t a t e governments and of mothproofing treatments have been discussed. tion class the protection is commer ci a1 organizations. Mothproofing with alkaloids, nitrogenous comlimited to the actual time The limitations of moth prepounds, and thiourea derivatives has been described. of fumigation (1). As soon ventives and fumigants such as the Fumigant is removed, as camphor, tar, cedar, etc., have encouraged the development of preparations which or even if poisonous gases are partially replaced by air, the are intended to render the fiber actually mothproof-i. e., fibers become again susceptible to moth attack. According to Back (1) naphthalene and paradichloronot edible by larvae-and an intensive study of this method of moth control has been under way in the writers’ labora- benzene are effective only if used as directed by the U. S. e., in sufficient quantity tories for a number of years. A \vide variety of chemical Department of Agriculture-i. substances has been investigated and tested with varying de- and in very tight chests. grees of success but this paper will be confined i,o a descripThe new method of moth control, the so-called “mothprooftion of experiments with several classes of chemicals with ing” treatment, is so devised that chemicals incorporated with which definite results have been obtained and which seem the fibers by contact with mothproofing liquid will continue especially interesting. Specifically they are nitrogenous their activity after the liquid is removed and the fibers become compounds, urea derivatives, alkaloids, and fluorides. dry again. The life cycle of clothes moths is divided by entomologists Larvae Tests into four stages: (1) egg, (2) larva, (3) pupa, (4) adult. The larval stage is the only stage where the moths require food The method of determining the degree of protection and where all damage to our woolens is done. This stage is also by far the longest. The other three stages taken to- afforded by various chemicals must, in the writers’ opinion, gether occupy about a 6 weeks’ period in a moth life, while be carefully considered before passing judgment on the value the larva stage lasts a t least several months, and often a of mothproofing agent. The effectiveness of moth preventives of the mothproofing class is not based on liberayear or more. The young larva when just hatched from the egg is of tion of some volatile substance; most chemicals of this class almost microscopic dimension. It has a white, translucent are quite stable. There is nothing in this treatment to warn body, which quickly (probably in the first 24 hours) acquires and repel larvae from the treated fabric. The larvae must the color of the woolen fibers upon which it immediately actually try to feed upon the fibers to discover that the food begins to feed, the food being plainly visible throughout the is uneatable. I n most cases the larvae are not killed by this digestive tract. Most of the dyes on woolen fibers remain trial bite, but they stop eating and, if there is no better food intact in the digestive tract of the larvae and thus they appear available, they eventually starve to death. Naturally the young larvae require less of the poisoned food to paralyze to be colored with the dye of the fibers ( 7 ) . The larvae are very sensitive to light and do their best to their activity than the more mature larvae. Accordingly the avoid it. When hatched on the fabric of a garment they hide damage done by larvae is in direct proportion to their appethemselves and feed in the pockets, cuffs, and folds of the tite and in reverse proportion to the effectiveness of the garment. It is therefore extremely difficult to detect larvae treatment. Three varieties of insects living on animal fibers were emon the garment in time to prevent damage. The only safe method is to penetrate all the fibers of the garment with some ployed in these studies-the webbing clothes moth ( T i n e o l a substance injurious to larvae. Uniform penetration can be biselliella), the casemaking clothes moth ( T i n e a pellionella), accomplished either by gas treatment or by wetting the and the black carpet bettle (Altagenus piceus). These variefabric with a suitable liquid. ties were found to be approximately equally resistant to different chemicals-i. e., if a treatment was found insufficient 1 Received August 10, 1929.
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HE problem of destroy-
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is decided by a single larva. On the other hand, if the treatment is strong enough to stand the attack of such a lama, then too it makes little difference how many larvae were placed on the piece. Koivever, a large number of larvao speeds up the test, and of course, if the treatment is not strong enough, a greater damage will be done by a larger number of larvae. Such a mature larvae test is undoubtedly severe aiid greatly cxamerates tho conditions which urcvail in the ordinary I~ouselrold,store, or storage .. . warehouse. In practice articles a r e seldom subjected to the inmediate attack of full-grown larvae. Tlte nsual condition is t.lrat wliicli exists when tire flying motit lays eggs vuliich s ~ i I ~ s e q ~ i ~ nliatcli t l y out into baby xvorms, arid these immature larvae arc naturally much less resistant to the action of u n f a v o r a b l e influences than mature larvae. As a result, a Plleenyluiea in Acetone urea in water Untreated t r e a t m e n t sufficient to give e o m pi c t e protection agaiiist the action of newly hatched larvae may not prevent severe damage when the material i s exposed to full-grown larvae. However, the writers liave tried to work with tiny young l a r v a e a n d found that tlie vourig worms ~vould usually hie in the dishes before any appreciable damage could be Diyhenyithiourea (Thiocarbanilide) Thiourea in Acetone in Acetone observed cven on untreated F W r e I-Larvae Teats on Fabrics Treated by Immersion In 2 Per Cen t soiutiona of urea ~ e r i ~ a t i v e spieces. Therefore, i n s p i t e of its severity, the test with exclusively. The dishes are kept in a dark place a t a uniform mature IaLrvae is beliemd to be more practical for comniercid temperature of approximately 26" C . for 2 to 3 weeks, or purposes. Another mctliod lras been suggested and used by Jackson until definite results have been established. Each case is controllcd by a parallel experiment in which an untreated and Wasscl ('?)-the placing of botli treated aiid untreated piece of the Same material is subjected to identical conditions. pieces in a cabinet filled with infested material. Although The effectiveness of tlie treatment under test can be judged this method more nearly approaches average household con(1) by observation of the extent of the actual damage to the ditions than the method described abwe, tlre present writers fibers; ( 2 ) by observation of the quantity of tlie excreta, do not consider it either positive or of practical commcrcial wliic.li, of course, is in direct proportion to the quantity of value. The Petri dish method with mature larvae gives a food consumed by the larvae; (3) in case of dyed fabrics, definite answer in 1 or 2 weeks, sometimes even in a few days; by the coloration of the excreta, also by the coloration in- while with the other method i t may be many mouths before side tiie digestive tract of the larvae. In cases where the one may reasonably become convinced that the treated fabric is very thick, and tile damage therefore not striking, fibers are immune. The writers also believe that tiie method used by Jackson the appearance and quantity of excreta give a valuable criand Wassel may lead t,o erroneous findings. In the first terion of the extent and development of the damage. In every series of experiments larvao of tlie same species place, a fabric treated with a chemical compound capable of and stock are always used and distributed evenly in each dish being eaten by moth larvae, but a t the same time somewhat of the series. In different series d8erent numbers of larvae distasteful, certainly would not be attacked to any great per dish are used. Altliough the damage is generally in extent when there was available a supply of much more proportion to the number of larvae in the dish, this is not desirable food-i. e., untreated woolen material. Furtheralways the case. Often an individual larva does more more, there being plenty of other food material available, striking damage than the others in the dish. When sucli mature larvae undoubtedly would not travel to thc treated a larva biiilds a cocoon or a web on a certain spot of the pieces in the cabinet, and the only damage w-ould be from fabric and st,icks to its structure, feeding upon the fabric the young larvae Iratclied from eggs accidentally deposited at the openings of the cocoon, tlien if protection on the fibers on the treated pieces by flying moths. Therefore such a test is not adequate tlre damage is apparent in a few days. Where does not seem to be a fair criterion of the susceptibility of the tlie fabric is not very thick, the larvae will cut right through fabric to moth darnage. it, making holes a t both ends of tlie cocoon. When such Nitrogenous Compounds as Mothproofing Agents an observation is made, the treatment is considered inDuring recent years r a n y chemical compounds have been sufficient. It is apparent for such a case that the number of larvae in the dish is immaterial. The whole experiment examined as mothproofing agents, many inventions patented against one, it ~vouldinvariably show ttie mine results when exposed to tlre attack of tlie other two. The black carpet beetles, however, are niricli easier to experiment with because they are far less susceptible to environment than tlie clothesmoth larvae. Fabrics to be tested arc exposed to direct larval attack in small Petri dishes by placing a number of larvae ranging froiii half a dozen to several dozens on a piece of material uf about one square inch in size. Mature larvae are used almost
ISDUSTI1IAL A N D ENGINBBRIKG CIfEMISTRY ( 9 ) , arid several pioductb devised for practical ube and placcd on tlie market Onr group of chemicals, coniistiiig of differriit inorgariw Rimme compounds, was tlie most favored and has met a coiisiderable commercial S U C C P ~ S Another group, apparently not yet commerciali~cd,hut undoubtedly possessing potentialities, includes a large riuiiibcr of diverse iiitrogeiious organic compounds covered in pateiiti by Lomrnel and Xunsel (6). Their ingenious formula
where K radical.
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