February 1, 1920.] 



THE INDIA RUBBER WORLD 



INTERESTING LETTERS FROM OUR READERS. 



To THE Editor : 



pvEAK SIR: — I was painfully surprised to read your answer 

 ^ to Mr. McCormick's query on page 148 of the December 

 issue of "The Ixdi.\ Rubber World." Whatever his inotive may 

 have been in writing you. it betrays a low grade of editorial 

 intellect for you to lose your temper as you did. And your slur 

 on the Chinese is particularly stupid. China is a great nation 

 with unlimited commercial possibilities for Americans. Obvi- 

 ously we have nothing to gain by antagonizing the Chinese, but 

 ought to do all we can to make our relations with them even 

 more friendly than they have been. 



P.\UL H. Schmidt. 

 Milwaukee, Wisconsin, January 3, 1920. 



ACCELERATOR INFORMATION. 



To THE Editor : 



r\EAR SIR: — If in keeping with your policy, I am wondering 

 *-^ if you will be kind enough to let me have an expression 

 from you on the relative strength of the following organic ac- 

 celerators as applied to the same compound, the known factors 



^ being the compound and the cure : 



' (1) Aniline oil 



i (2) Thiocarbanilide 



(3) Hexamethylene-tetramine. 



(4) Paraphenylene-diamine. 



As a concrete example, if the following formula were used 

 taking hexamethylene-tetramine as a standard, using say one 

 pound, what amounts of the other accelerators above mentioned, 

 each in turn, would be required to replace the "Hexa" for the 

 same cure : 



Sulphur 2 pounds 8 ounces 



Hexa 1 pound ounces 



Zinc oxide 5 pounds ounces 



Smoked sheets 91 pounds 8 ounces 



100 pounds ounces 

 Cure : Say, 1 hour and 45 minutes at 45 pounds.. If this for- 

 mula and cure will not suffice, then any one which you might 

 be willing to suggest will be greatly appreciated. 



What method would you recommend as being the most sat- 

 isfactory for treating crude rubber (smoked sheets) with para- 

 phenylene-diamine ? 



If a solution of paraphenylene-diamine is used : — 



(a) What strength is generally required? 



(b) What length of time would be required to treat the 



rubber ? 



(c) What temperature would you recommend to keep the 



solution while treating rubber? 



(d) About what percentage of para-phenylene-diamine 



would the rubber contain after treating and being 

 air-dried? 



X. 



A friendly rubber chemist comments upon the foregoing as 

 follows : 



A categorical answer to the first question is exceedingly diffi- 

 cult, for the reason that it presupposes a method of determining 

 equal conditions of cure. In other words, it involves a defini- 

 tion of the so-called "optimum" cure, about which so much has 

 been written and so little agreed upon. I presume that your 

 correspondent would regard similar conditions of tensile strength 

 and stretch as being indicative of the same cure, as they doubt- 

 less are from the standpoint of the practical rubber worker. 



With this definition of cure then, the answer to your corre- 

 spondent's question is, "It can't be done." I don't think the ad- 

 dition of any amount of aniline oil to the formula stated will 

 bring about a tensile strength equal to that obtainable by means 

 of the 1 per cent hexa. I also believe that it would be diffi- 

 cult to duplicate with hexa the physical tests obtained with 

 paraphenylene-diamine. In other words, no quantitative equiva- 

 lent relationship exists for the four accelerators in question. 



The situation is precisely similar in the case of the inorganic 

 accelerators. Supposing one were asked to state the numerical 

 relationship between white lead, litharge, lime and magnesia. 

 It can't be done. 



In the case of the organic accelerators, it can, however, be 

 stated with accuracy, that their order of potency is in accord- 

 ance with the order in which they are stated in letter, aniline 

 oil being the least powerful and paraphenylene-diamine being 

 the most so. 



Regarding the second series of questions as to the conditions 

 of treati,ng crude rubber with paraphenylene-diamine, I cannot 

 be of much assistance, for the reason, very franklv, that I do 

 not know the answer to them. I have had very little experience 

 with paraphenylene-diamine because I feel that owing to its 

 frightfully poisonous nature, it has no place in the rubber fac- 

 tory. Whenever I am asked regarding the advisability of using 

 this accelerator, I am always tempted to quote Punch's advice 

 to those about to get married : "Don't." 



Chemist, 

 frolf a weix-known rubber expert. 

 I have for some time been trying to learn the use of para- 

 phenylene-diamine, which is handled successfully by only a few. 

 So far I am not sufficiently informed to give information worth 

 while. 



Regarding aniline oil, this material is fast being replaced by 

 other materials because of its bad effect upon the people who 

 handle it. It produces inefficiency from the office to the stable. 

 Under the same conditions these accelerators I think would be 

 used in about the same quantity except the fourth or last men- 

 tioned. 



Hexamethylene-tetramine.— The results are very good, but it 

 produces an itching that is unbearable. 



Thiocarbanalide is also very good when clean, but much of it 

 contains free nitro benzol, which, of course, is dangerous and 

 should not be used. It is used in about the same quantity as the 

 others, but is made safe by careful supervision and cleaned and 

 kept clean throughout. Have had the best of success with it. 



Some manufacturers use sulphuric acid in making a material 

 they call by the name of thiocarbanalide. It has been proved 

 to be detrimental in same instances by weakening the fabric, 

 causing blow-outs. 



To THE Editor: 



r\EAR SIR: The alleged confessions of a certain big gambler 

 ^-^ as chronicled in some of the daily papers describe the fleec- 

 ing of a wealthy man entitled the "Rubber King." Who is he? 

 Boston, January 1. 1920. I. I. Reynolds. 



(There are really scores of "rubber kings" in the preferred 

 imaginations of dark-alley word-blacksmiths. Any man of 

 wealth or prominence in the world is eligible. All that is nec- 

 essar)- is a paper that will print and pay for the stuff— a few 

 facts (or fancies), a so-called rubber king, unnamed of course, 

 and much white paper is ruined. — The Editor.) 



WITH REGARD TO SOLARIZATION. 



To the Editor : 



r\EAR SIR :— .-X rubber man in the East sends me a compound 

 *-^ for blue rubber that, as I understand it, is to be coated on 

 cloth, then wrapped in muslin and vulcanized in the roll. He 

 says, dry heat. Possibly he means that it should be hung or 

 festooned in a hot-room. The compound calls for rubber, zinc 

 oxide, ultramarine blue and sulphur. The amount of sulphur 

 used is one ounce to the pound of rubber. Now. I can easily 

 put the mixture in solution and spread it, but I am not sure 

 that I wish to make a dry heater. 



Out here we have moisture most of the time. I have been 

 told that sunlight will cure surface goods. Is that so, and is the 

 compound just the same as for the dry heat? How can I try 

 this out? John J. Adams 



Pasadena, California. 



(It is perfectly feasible to cure surface goods by exposure to 

 sunlight. It is commonly called "solarizing." Use ^ ounce of 

 sulphur instead of 1 ounce. Make the solution thin and run 



