THE INDIA RUBBER WORLD 



305 



The apparatus for generating the hydrochloric gas consists of 

 a double tubular flask containing hydrochloric acid at 22 degrees 

 Beaume. To one of the tubulures is attached a funnel with 

 an S-bend for safety against back pressure of the gas forcing 

 out the supply of sulphuric acid contained in the funnel. 



The length of the branches of the S-bend may be 15 to 20 

 centimeters. For drying the gas the second tubulure of the ap- 

 paratus connects with two tubes containing broken pumice 

 wet with sulphuric acid, and with a gas washer filled with 

 fuming sulphuric acid. The gas generator is stoppered with 

 paraffine-boiled, tinfoil-covered cork stoppers and sealed with 

 paraffine. Sulphuric acid (66 degrees Beaume) is delivered from 

 the funnel, drop by drop, into the dilute hydrochloric acid in 

 the flask. The hydrochloric gas disengaged carries along a 

 little hydrochloric acid and moisture. The latter is retained by 

 the pumice, which serves as a gas filter and dehydrator. The 

 gas produced should not react blue on powdered copper 

 sulphate. The passage of gas through the powdered rubber is 

 easily controlled by regulation of the vacuum connection with 

 the flask and absorption train. The application of vacuum is 

 made cautiously so that the sulphuric acid will not be drawn 

 into the generator abruptly. The difference in level should not 

 exceed two to three centimeters of mercury in order that the 

 contact of the gas with the powdered rubber may be as pro- 

 longed as possible. 



Chlorhydr.^ting Effect. 



The action of the gas on the rubber liberates some heat. 

 This temperature is not allowed to exceed 35 degrees C. The 

 chlorhydration reaction proceeds slowly, and if the temperature 

 rises, the mass tends to become sticky at 35 degrees C, the 

 powder becomes a little tacky but does not unite enough to 

 prevent passage of the gas. 



Complete chlorhydration requires 24 hours. The product ob- 

 tained is nearly white and retains its elasticity. It is removed 

 from the flask, washed with warm water, then with cold, until 

 the wash water is free of acid. Next follows washing with 

 warm alcohol, then with cold alcohol, drying at 60 degrees C, 

 ' and cooling in a dessiccator. Tlie rubber is then in the form 

 of an easily pulverizable white powder, insoluble in alcohol, 

 ether, acetone, benzine and sulphide of carbon. It consists of 

 a mixture of three chlorhydrates of caoutchouc: (1) chlor- 

 hydrate of polyprene sulphide, (2) chlorhydrate of stable (vul- 

 canized) caoutchouc, (3) chlorhydrate of metastable (unvul- 

 canized) caoutchouc, or caoutchouc in its natural state. The 

 first two forms are completely insoluble in chloroform, while 

 the third is completely soluble. 



Separation of Chlorhydrated Product. 

 There are three different methods by which the amount of 

 unvulcanized caoutchouc in the sample may be determined. 



1. A known weight of the dr>' chlorhydrated material is 

 treated with chloroform and the insoluble residue dried at 60 

 degrees C, cooled in a desiccator, and weighed. The difference 

 between the two weights gives that of the chloroform soluble 

 chlorhydrate or unvulcanized caoutchouc. The formula for 

 this chlorhydrate is QoHibCIj, therefore 1.99 grams of the 

 chlorhydrate correspond to 1.36 grams of caoutchouc. 



2. The unvulcanized caoutchouc may be similarly calculated 

 from the weight of dry residue obtained by evaporation of the 

 chloroform extract. 



3. The dry chlorhydrate, if treated on a water-bath with 

 pyrridine or pyrridine bases, gives up its hydrochloric acid and 

 assumes the gummy state of unvulcanized caoutchouc. Aniline 

 has the same reaction, but the unvulcanized caoutchouc is 

 partly soluble in it, necessitating precipitation. The use of 

 pyrridine is the more practical, as follows: the chlorhydrate 

 of unvulcanized caoutchouc is extracted for six hours with 

 100 cc. of pyrridine, using a reflux condenser. The caoutchouc, 



which floats as wliite threads in the liquid, is received on a 

 tared filter; to the filtrate is added twice its volume of acetone 

 to precipitate the dissolved caoutchouc. The residue is washed 

 with hot and with cold acetone, then with 95 per cent alcohol, 

 dried at 60 degrees C. in vacuum, cooled in a desiccator, and 

 weighed. 



The caoutchouc thus separated has all the characteristics of 

 the natural gum. It is elastic, slightly sticky, easily erases pen- 

 cil marks, and dissolves completely in all the usual caoutchouc 

 solvents forming viscous solutions. 



Before making this determination it is well to eliminate from 

 the vulcanized rubber the different organic additions which it 

 may contain and which may render the results faulty, by mak- 

 ing preliminary extractions with acetone, chloroform and alco- 

 holic-potash. 



This process is not only suitable as an anal>'tic method, but 

 can be utilized industrially for the separation of unvulcanized 

 caoutchouc present in waste rubber. 



CHEMICAL PATENTS. 



THE UNITED STATES. 



COMPOSITION FOR Soles.— Composition and soles of vulcaniz- 

 able material consisting of a mixture of comminuted waste 

 felt roofing saturated and treated with asphaltum and boiled linseed 

 oil ; reclaimed rubber, litharge, sulphur, and zinc oxide. (George 

 R. Wyman and Andrew E. Currier, assignors to Charles S. Bird, 

 all of Walpole, Massachusetts. United States patent No 

 1,284,023.) 



Artificial Rubber and Process of Making.— A composition 

 of matter for use in the manufacture of artificial rubber, includ- 

 ing vulcanizable vegetable oils, resinous hydrocarbon bodies, 

 camphor, powdered shale and sulphur. (Edwin R. Talley, Grin- 

 nell, Iowa. United States patent No. 1,285,463.) 



Rubber Derivatives and Process.— A plastic oxidation 

 product of rubber produced by treating a natural rubber with 

 an oxidizing agent (ozone) in the presence of water and 

 copper oleate. (Walter O. Snelling, Pittsburgh, Pennsylvania, 

 United States Patent No. 1,288,723). 



Synthetic Rubber Process. — A process of making a rubber- 

 like substance by synthesis which comprises heating a mixture 

 of pinene and an acid until the pinene is changed into limonene 

 raising the temperature of the mixed vapors until the limonene 

 is partly changed into a rubber-like substance, condensing the 

 vapors, and removing the acid. (Louis Gottschalk, Metuchen, 

 New Jersey; Esther J. Gottschalk, administratrix of said Louis 

 Gottschalk, deceased. United States patent No 1,289,444.) 



Material Comprising Metal and Vulcanized Rubber. — 

 Rubber vulcanized by an agent containing oxygen and a me- 

 tallic material attached thereto. (Albert A. Somerville, Flush- 

 ing, New York, and Mahlon J. Rentschler, Willoughby, Ohio, as- 

 signors to Rubber Regenerating Company, Naugatuck, Connec- 

 ticut, United States patent No. 1,289,566.) 



Process of Preparing Tire-Treads. — On a tire-tread a band 

 of vegetable fiber is formed, impregnated with hot tar and 

 rosin. After cooling, grit is applied to the prepared surface. 

 (Delaska A. Kendall, San Diego, California. United States 

 patent No. 1,290,576.) 



THE DOMINION OF CANADA. 



VtiLCANizABLE- Composition and Product. — A vulcanized, com- 

 position rubber product comprising natural and reclaimed rub- 

 ber, coumarone resin, sulphur, and extending materials. (Alfrec 

 Alonzo Wells, Montclair, N. J., U. S. A. Canadian patent No. 

 186,812.) 



Treatment of Fabric— The treatment of fabric by impreg- 

 nation and the product of the process patented. The process 



