S9S 



THE INDIA RUBBER WORLD 



Sf.i'Tember 1, 1921 



rubber manufacturers too often or too strongly : the presence of 

 alkaline chlorides, or alkaline earth chlorides, either in the rub- 

 ber or in the sizing of the fabrics. 



ACETIC ACID CAUSES STICKINESS 



Under the same conditions of exposure to light and of tem- 

 perature, Landolphia bark or thin sheets of rubber, impreg- 

 nated with very dilute solutions of acetic acid and carbolic acid, 

 change in fifteen days and the sticking action develops with 

 rapidity. This phenomenon is produced even in samples placed 

 in sealed tubes or in flasks with ground stoppers which have 

 been previously sterilized. The action of acetic acid is particu- 

 larly important as it is used universally in producing the coagula- 

 tion of plantation rubber. 



Rubber which has not been washed sufficiently after coagula- 

 tion and contains traces of acetic acid, is capable of becoming 

 sticky very rapidly, particularly when in the form of thin sheets. 

 This is the case with rubberized cloth. 



DRY RUBBER IMMUNE IN THE DARK 



Rubber free from harmful substances, or rubber coagulated 

 with salt, but absolutely dry, does not deteriorate no matter how 

 long it is exposed to the action of heat in the dark. The enzymes 

 to which the deteriorative action is assigned, are incapable of 

 acting in an anhydrous medium. However, if moisture is present 

 then sticking takes place at once on standard rubber as well as 

 on the salted rubber. Moreover, the development of the sticking 

 action is more rapid as the temperature increases. 



SUN BURNED RUBBER 



Three samples of Landolphia rubber were exposed to sunlight. 

 One was placed in dry air, another in an atmosphere saturated 

 with moisture and the third in water. At the end of two hours 

 the first two samples had become sticky. The sample placed in 

 an atmosphere saturated with moisture was even more strongly 

 attacked by this deteriorative phenomenon than the sample in the 

 dry atmosphere. This difference becomes more pronounced as 

 the exposure to the sun increases. On the other hand, the sam- 

 ple immersed in water did not undergo any change, even after 

 an exposure to the sun for twenty days. 



Other samples of rubber were exposed to direct sunlight, one 

 under water, the other under a protective covering of a saturated 

 solution of alum. After four hours, the first sample became 

 sticky while the other remained intact. 



We may therefore conclude that it is the heat of the sun that 

 brings about the phenomenon of sticking. The raw rubber is 

 burnt to a certain extent, analogous in a marked degree to the 

 action of the sun's rays on the skin, resulting in sunburn. 



UGHT, HUMIDITY AND ELEVATION 



Light of moderate intensity does not produce the sticking, even 

 at the end of three years of exposure. If the light is strong, 

 however, the rubber becomes sticky. The rapidity of this action 

 increases as the humidity of the air becomes greater. An elevated 

 temperature promotes the reaction. 



The action is very marked on ordinary commercial Landolphia 

 rubber in balls, and at a constant temperature it is more rapid 

 than on the samples described above. The ease with which 

 sticking is produced is probably due to the salt that is used in 

 the coagulation process. 



DUBOSC'S AGREEMENT WITH BRINDEJONC 



In my agreement with Brindejonc, T have coiilirmcd by re- 

 peated experiment that once sticking commences in a rub- 

 ber, no matter what the cause of the same may be — the action of 

 light, the presence of acids or chlorides — the phenomenon con- 

 tinues and it is not possible to restrain its action. 



If the rubber containing the substances causing sticking in the 

 dark has not yet been attacked, then a prompt, vigorous, and 

 thorough washing is the best way to prevent the action from 

 setting in. If the phenomenon has set in, it is then impossible 



to stop it, as formaldehyde, bisulphite and all the other anti- 

 septics are of no a\ail. 



FALL MEETING OF AMERICAN CHEMICAL SOCIETY 



riE fall meeting of the American Chemical Society will be held 

 with the New York Section, September 6-10, and will prob- 

 ably be the largest meeting that has yet been held. There are 

 2,500 members in the New York section alone, while thousands of 

 other members are within a few hours' ride of the city. In addi- 

 tion to these a considerable nimiber of British and Canadian 

 members of the Society of Chemical Industry are ex- 

 pected, who will have held their annual meeting in 

 Canada. They will be greeted at the border by the 

 Governor of this state, and will arrive in New York, 

 September 7. After being the guests of the American Sec- 

 tion of the Society of Chemical Industry at luncheon September 7, 

 they will then become guests of the American Chemical Society 

 for the remainder of the week. Three or four hundred British 

 and Canadian members will probably be present, as well as three 

 or four thousand from the American Chemical Society. 



Accommodations will be provided at the Waldorf-Astoria hotel, 

 Fifth avenue and 33rd street. New York, the headquarters for 

 the meeting. In addition Columbia University has offered the 

 facilities of its dormitories. Rooms for men, rooms for women, 

 and rooms for married couples have been reserved at the rate 

 of $1.50 per day per person, with a maximum per person of $10 

 for the period September 6-16, for those wishing to stay for the 

 Chemical Exposition. Applications, giving names of those in 

 party, type of reservation desired, maximum price per day per 

 person, time of arrival, expected departure, should be forwarded 

 to Charles F. Lindsay, chairman of the Hotels Committee, care 

 of United States Rubber Co., 1790 Broadway, New York. All 

 members and their guests, including ladies, should register im- 

 mediately upon arrival. The registration office will open at The 

 Chemists' Club, 52 East Forty-first street, Tuesday morning, 

 September 6. After Tuesday it will be at Columbia University. 



The Council Meeting on September 6, will be held at The 

 Chemists' Club. All general, divisional, and public meetings, will 

 be held at Columbia L'niversity. 



RUBBER DIVISION MEETINGS 



The meeting of the Rubber Division will be held September 

 7-9, at Columbia University. The tentative program is as fol- 

 lows: 



1. "The Tetra-Hydro.Kyphenyl Derivative of Rubber and its 

 Tetra-Methyl Ether." Harry L. Fisher and Harold Gray. 



2. "Mineral Rubber." C. O. North. 



3. "The Determination of the Particle Size of Pigments." W. 

 W. Vogt. 



4. "The Action of Volatile Organic Solvents and Vulcanizing 

 Agents on Organic Compounding Materials and Resinous Gums." 

 Frederic Dannerth. 



5. "Corrected Stress-Strain Curves for Rubber." J. W. 

 Shields. 



THE SEVENTH NATIONAL EXPOSITION OF CHEMICAL 

 INDUSTRIES 



The Seventh National Exposition of Chemical Industries, 

 which will be held September 12-17, in the Eighth Coast Artillery 

 Armory, New York, N. Y., will undoubtedly prove to be the big- 

 gest chemical event in the history of the country. The growth of 

 the industry during the last seven years is plainly indicated by 

 the extent of the exhibits, as more than 400 will be displayed on 

 one floor. 



The interest shown this year in the exposition by foreign coun- 

 tries is an important feature. Great Britain and Canada will 

 undoubtedly be well represented in various ways, while many 

 scientists and chemists who will attend the meetings of the Ameri- 

 can Chemical Society are expected to be present at the Exposition. 



