EXAMINATION OF BITUMINOUS EOAD MATERIALS. 25 



DIMETHYL SULPHATE TEST. 



EQUIPMENT. 



Same as specified under distillation test, and in addition: 3 10-cubic centimeter 

 glass cylinders -with ground-glass stoppers, graduated to 0.2 cubic centimeter. 



The dimethyl sulphate test is employed to detect the presence of 

 petroleum or asphalt products in tar. The pitch (above 300° C.) 

 obtained from the distillation test is used. This pitch, after being 

 cooled and weighed, is again distilled. Fractions are taken at 350° C. 

 and 375° C. These fractions, together with the 270-300° C. fraction 

 previously obtained, are separately stirred and, if necessary, heated 

 to dissolve solids which may be present. 



Four cubic centimeters of distillate from each fraction are separately 

 shaken with 6 cubic centimeters of dimethyl sulphate in a 10-cubic 

 centimeter cylinder. After standing 30 minutes the resulting super- 

 natant layer of insoluble oil, from the petroleum or asphalt, is read 

 and calculated to its percentage by volume of the sample of distillate 

 taken. The results are reported as follows: 



Fractions. 



Per cent 

 of distillate. 



Per cent 

 of distillate 

 insoluble 



in 

 dimethyl 

 sulphate. 



270° to 300° O 







300° to 350° C 







350° to 375° C 













USE OF DIMETHYL SULPHATE TEST. 



The dimethyl sulphate test is used only in cases where a mixture 

 of petroleum or asphalt products with tar has been specified or is 

 suspected. The test is mainly qualitative, but is valuable when as 

 little as 3 per cent of petroleum or asphalt products are present in the 

 fcar. 



DETERMINATION OF BITUMEN SOLUBLE IN CARBON BISULPHIDE. 



EQUIPMENT. 



i LOO cubic ce itimeter Erlenmeyer flask. 



i 500 ■ ubic centimeter flasl u Lth side neck for filtering under pressure. 

 I rubber . topper with one hole. 

 i filter tube 3 9 ce itim< fcers, Lni Lde diameter. 

 i platinum or porcelain < rooch crucible. 



I piece --I eamlee ■ rubber tubii ". aboul 3 centimeters in diameter and 3 centimeters 

 I i g 



fiber amphiboli a be to 



