THE INDIA RUBBER WORLD 



hose for general use in conveying steam or hot water inider 

 pressure: also for car heating purposes. 



(fc) See War Department Specification Xo. 333—1—1, headetl 

 General Specification for Mechanical Kubher Goods, which is 

 made a part hereof, except in such cases as the provisions below 

 directly conflict. In such cases the word and meaning of this 

 specilicaiion w'ill govern. 



Construction. — See General Specifications. 



(a) Dimensions.— See the following table. 



(/>) No washers to be furnished. 



Br.^nding.— See General Specifications. 



(a) Use the word "Steam." 



Maieri.\l. — See General Specifications, 



Inspection.— See General Specifications. 



(a) Inspector may select four lengths at random trom each 

 shipment of 100 lengths or less, and cut from each length se- 

 lected a 3-foot section ; two sections for steaming and the others 

 for remaining tesis. 



Tests.— See General Specifications and following table. 

 (0) Test specimens shall not be bufTed. 



(b) Steaming.— The ultimate tensile strength shall be de- 

 termined by using the original thickness of samples in calculat- 

 ing the area. When calculating the tensile strength after steaiii- 

 ing the test piece shall be considered as having the same thick- 

 ness as that used before steaming. 



A sample not less than 18 inches long shall be subjected to 

 dry saturated steam in a digester for a period of 48 hours at a 

 pressure of 4S pounds. After this test, the tube and cover shall 

 not show any blisters, nor loosen from the plies of fabric. After 

 resting, test piece shall be cut at least 4 inches from end and 

 shall meet the figures indicated in the following table : 



(I. D.) J^lNC 



Befoi. 

 After 



(To be continued.) 



Detection and Determination of Glue in Rubber Goods. 



By S. IV. Epstein 



GLUE is one of the latest additions to the long list of 

 materials which have found application in rubber com- 

 pounding. Its use has been attended with such strik- 

 ing success that it is becoming more and more prevalent in 

 rubber stocks. As a consequence, the rubber analyst has 

 another organic constituent to contend with in the determi- 

 nation of rubber hydrocarbon by diflference. In order to 

 be able to rely upon the figure for rubber hydrocarbon in 

 a rubber mixing, it is necessary to know whether or not 



glue is present and when it 

 termined. 



The use of glue in rubber 

 thing that up to the present 

 have received little attention. 



is, the quantity must be de- 



is such a comparatively recent 

 its detection and determination 

 After one has found out that 

 it is impossible to extract the glue from a cured rubber stock 

 by means of boiling water, the problem of finding a satisfac- 

 tory method takes on a formidable aspect. The problem 

 presented two angles from which it could be attacked, 

 namely: (1) by dissolving away the rubber and leaving the 

 glue unchanged so that it could be dissolved in water and 

 the glue determined by the weight of the water extract; (2) 

 by determining the nitrogen content and calculating this to 

 glue by means of the factor 5.56. 



Believing that a Kjeldahl determination is too long for 

 ordinary laboratory practice, we undertook to dissolve the 

 rubber and attempted to get the glue in the residue. We 

 found that the nitrosite and bromine methods of converting 

 rubber into a soluble derivative could not be used since the 

 glue seemed to be acted upon. The residue, which was left 

 after the removal of the rubber compounds, when extracted 

 and digested with hot water, gave extracts which contained 

 less than 50 per cent of the total glue present; in addition. 



of the Dii 



of the Bun 



of 





Tiid W. E. Lange. 



this water solution would give none of the tests which are 

 used to detect the presence of glue. 



We next directed attention to rubber solvents, especially 

 to those which would dissolve rubber at comparatively low 

 temperatures, since a high boiling solvent decomposes the 

 glue and is therefore inapplicable. After considerable ex- 

 perimentation it was found that cresol seemed to be satisfac- 

 tory for the purpose. Rubber can be dissolved in it and the 

 resulting solution, after it has been diluted with petroleum 

 ether, can be filtered with ease. When glue is treated with 

 cresol, it dissolves very readily but is precipitated in large 

 part from this solution on the addition of petroleum ether. 

 Experiments showed that on the average about 70 per cent 

 of the glue could be precipitated from its cresol solution. 

 The precipitation, therefore, could not be used as a quan- 

 titative procedure for a glue determination. However, this 

 precipitate settled out very well and dissolved readily in 

 water, giving a solution which answers all the tests for glue 

 and the procedure can be used as the basis of a qualitative 

 test for glue in rubber "mixings." 



QUALITATIVE METHOD. 



About O.S-gram of ihe rubber sample to be tested for the 

 presence of glue is digested in 25 cc. of freshly distilled cresol 

 (boiling point 195 degrees C.) in a tall beaker for about 16 

 hours at 120 degrees C. This digestion is conveniently car- 

 ried out by placing the beakers in a properly regulated Freas 

 oven and allowing them to remain there over night. The 

 cresol solution is allowed to cool and 250 cc. of petroleum 

 ether is added slowly with constant agitation. When this 

 solution has settled and the supernatant liquid is clear it is 

 filtered through a Gooch crucible, using gentle suction. The 

 beaker, contents and crucible are washed thoroughly with 

 petroleum ether, then with hot benzol. The pad is removed 

 from the crucible, placed inside of the beaker and digested 



