M 1:1 K 1. 1915. 



THE INDIA RUBBER WORLD 



653 



rformed bj using petroleum ether. Aqueous alkaline solu- 

 tions "i slightl) alcoholic solutions cannol i asilj be c ractei 

 with petroleum ether on account of the formation ol persistent 

 emulsions. The petroleum solution is separated, then washed, 



vrith a small quantity of concentrated sulphuric acid, then 

 with a solution of one-half normal alcoholic potash, and finally 

 it is i iporafc d and dried in th< u ual manner. 



PROP' ■ S-VCLCANI Z I 



After the free sulphur and the non saponifiabli ub tances are 

 ,ved from the a etone extra* t, the nor <mh anized oil is ob 

 tained The residui thai is non-soluble in acetone is vulcan 

 .ill or factii i 



UMI\ \i i.o - -1 5ULPHI R \ND < HLORIN1 I OMBINED. 



To determine the proportion of sulphur, and of chlorine combined 



from .5 gram to 1 gram of brown fai tio is taken from the ai ■ 



.extraction residue and treated according to the method ol 



i qucz or a i ording to that oi Pontio. I he substance is 



slowlj heated in an iron retort with 10 grams of caustic soda 



;in ,l jo per cenl i alcohi 1 I his i lusi thi Ea< ti i to dissolve. 



The solvent is then slowly evaporated, one liter oi water added 



:., wholi ■<■ nglj heated wink- it is constantlj being stirred. 



I hi organic matter is heated until it smokes and thickens into 



lgll , that shows a tendencj al some points to become in- 



.eandescer rhen peroxide oi sodium is slowly and proi 



tdded i" small portions with a spatula while the stirring 

 is o iiitinued. 



As the peroxide is added the liquid becomes more and more 

 and finallj becomes Mack through the formation of fer- 

 rate-.. Care must be taken to divide thi peroxide o that it will 

 be thorough!) mixed with the mass and will thus produce uni- 



i The mass is then coi led and treated v it! 

 ter. If there is no chlorine the solution is acidified with hydro- 

 chloric acid, boiled and precipitated bj chloride of barium. 

 Where there is chlorine, the solution is divided into two parts, 

 which an one with hydrochlorii acid, the other with 



nitric acid, and the sulphur contents determined with barium 

 ■chloride and the chlorine by nitrate of silver. 



M i,.'in riOX Ol TOTAl 3 CI PHI R MOISTURE, I REE ACID 

 \M> \SH 



The total sulphur can be determined bj one of the usual meth- 

 ods applied lo the original substitute. The combined sulphur is 

 always found rather low in brown substitutes, 



Moisture is rareh determined in brown substitute. When the 

 mposition of white substitute is rather advanced, it contains 

 .a small percentag. of moisture. Ii may be determined by drying 

 at go i , : tigrade i 140 degrees Fahrenheit). 



There is always tree acid in rubber substitutes, but the amount 

 rarely exceeds 2 per cent., figured as oleic acid. It is rather 

 harmless or not mon troublesome than non-vulcanized oil. In 

 substitutes that are in a state of decomposition free sulphuric 

 , [J i« ft, : E. ind and it can be determined by washing the 

 substitute in hoi a .i" and by titrating the sulphuric acid in the 

 wash Water 1>\ barium chloride 



Ash amounts to about 1 per cent, in brown substitutes and is 

 ,,,- no impdrtam In manufacturing white substitute a little lime 

 nag'nesia is often added to neutralize the hydrochloric acid 

 ■ created during decompoistion. 



The proportion of ash in white substitute is not generally de- 

 termined quantitively, but only examined qualitively. 



The following figures, quoted from "l.e Caoutchouc & la Gutta- 

 percha," ypical rubber substitutes: 



\\ 111 I 1 SUBSTITUTE. 



English German Frencl 



\ : I" r cent. 10.3 7.7 13.8 



i i sulphur ', 



Vulcanized oil ■ 8 ^ 8 ?i 8 ij 



Chlorine 7 -« \] 7 \ 



Ash >■" - 6 J - 8 



BROWN I i i ... I i in L)Ri II \RBONS. 



i ... ^ French 



Hard Medium Soft Medium 



ed oi! pei ■' •"■- 



0.1 1-5 



£25 oii ' \ ~] J 



Combined sulphur 9-f 



0.1 0.1 0.6 



BROWN SUBS1 I ' FINING HYDROt VRBI 



f — Fine Para — ■, 

 ... French 



il per cent. 25.1 10. 6 23.0 23.4 



«■? * 



, 20.1 21.3 25.2 



Mineral oil • • : • • ■ 



oil 51.3 64.6 52.5 47.9 



Combined sulphur 13.8 13.» 



In general the besi substitute is the one that contains the li 

 non-vulcanized oil beca this ..il is the same as 



if the oil were siinph mixed with the rubber, that is, it li 

 the life oi the rubbei Mineral oils are les us, in this 



connection, than veg I and pai entirely neutral. 



I ..,- mixing rubbei with the above substiti 



rtions may be adopted: Thirty parts of French Para 

 stitute ma d to 100 pei cent, of rubbjer, with 8 or " pei 



cent, oi paraffin, As a matter of fact paraffin can be bven used 

 in a greater proportion. 



The prop. ash in a substitute must not i eed reason- 



able limits. 4 per cent. and should contain more 



of magnesia than ol time Ma ■■■■ ia ith a little oil, produces 

 a non-deliquescent de. The presence of hygroscopic 



substances causes rubber substitutes to d> while in 



storage. 



I., recapitulate, the best substitutes are those that, in their 

 crude state, are driest and least coherent, the sulphur and 

 chlorine together not exceeding 20 per cent. 



Brown substitutes, and sometimes white substitutes, offer a 

 great varietj of mechanical consist i - cording to the ratio 



of non-vulcanized and non-saponi redients to the com- 



bined sulphur. The low vulcanizal qualities makes 



soft products that are sticky and Well vulcanized, 



on the contrary, they are firm and strong. These properties are 

 ,.i Hi. greatest importance in determining the substitute to be 

 used in a given mixture. 



Substitutes as received should be extracted with acetone to 

 determine the frei sulphur and the non-saponifiable parts. Rub- 

 ber substitutes of the same make should not vary greatly m con- 

 sistency, and the percentage ol ould remain constant 

 ; n the neighb rh 1 of 2 per cenl The mechanical propertii - oi 



Substitutes of different make- can onlj approximated be deter- 

 mined by analysis. I oi instance, two samples, made of different 

 oils, ni.: gi . the -.one acetonic extract- and the sami 

 centage ol combined sulphur and yet be verj different. In such 

 - mixing and vulcanization test- should be made. 

 Ih. knowledge of the percentage of free sulphur is important 

 for figuring compounds More than 3 per cent denotes either 

 defective manufacture or reversion while in storage. 



Methods for analyzing oils are applicable onlj to a slight ex- 

 tent to rubber substitutes, and the indications e con- 

 raw iuaicn.il- used are mi and of little in- 

 terest to the rubber manufacturer. 



I p,. figures representing saponification in substitutes are al- 

 ways . than those for oils, and an not constant unless 



rous methods are employed ["he; an in the neighborhood 

 of 300 for white substitute and 100 for the brown. The pi 

 tions of fatty acd- plaj an important part in the general analysis 

 of rubber. 



Should ery rubber man's desk— Crude Rubber and 



, ndinj [redients; Rubber Country of the Amazon; 



Rubber Trade Directory of the World. 



