April 11, 1913] 



SCIENCE 



575 



the consistency of a pitch and drawn in physical 

 terms are particularly appropriate for physical 

 work such as road-building, and such specifications 

 are more likely to be readily understood than 

 where chemical expressions are used, perhaps to 

 cover the same points in a less direct way. 



The writer believes that valuable research work 

 can be done by investigations into the consistency 

 of bituminous materials or pitch compounds, and 

 that from such work the art of road-building will 

 be advanced. 



The Value of Specifications and Tests for Bi- 

 tuminous Materials: Charles S. Eeeve, chemist, 

 TJ. S. Office of Public Eoads, Washington, D. C. 

 The author urges the importance of purchasing 

 bituminous materials upon a specification. The 

 maker of such a specification, however, should 

 know the relations to one another of the particular 

 characteristics he demands, and the ability of the 

 producer to meet his requirements. Advance 

 samples and shipments should be tested to insure 

 the acceptance of satisfactory material and to 

 furnish records of tests which may prove of value 

 later. Examples of recent neglect to fulfil certain 

 specifications are given, and in some oases this 

 neglect would have proved serious but for the fact 

 that careful inspection averted the use of the 

 undesirable materials. The practise of purchasing 

 upon a trade name only is criticized, and an 

 example is cited which shows a recent failure due 

 to this practise. The author concludes by urging 

 the highway engineer to protect himself by the 

 careful purchase and inspection of materials. 



The Evaporation of Bituminous Materials, its 

 Determination and Value in Specifications: 

 Prevost Hubbard, in charge Division of Roads 

 and Pavements, The Institute of Industrial Re- 

 search, Washington, D. C. 

 Read by title. 



Fixed Carhon in Bituminous Materials, its Deter- 

 mination and Value in Specifications: Lester 

 KiRSCHBRAUN, director, Chicago Paving Labo- 

 ratory, Chicago, 111. 



The writer describes the standard method of 

 determining fixed carbon in bitumens, and points 

 out some of the factors of manipulation necessary 

 of observance in order to obtain correct and con- 

 sistent results. A discussion of the derivation of 

 fixed carbon produced upon ignition of bitumens 

 is given, and its significance applied in three par- 

 ticulars. First, as a means of identification of 

 certain native bitumens; secondly, as a means of 



checking the suitability of combinations of flux 

 solvents with hard, highly condensed bitumens; 

 and again, as applied to oil asphalts, as an index 

 of the severity of heat treatment to which such 

 materials have been subjected in the course of 

 their production. This latter feature is demon- 

 strated by graphical data showing the effect upon 

 the fixed carbon yield in runs of oil asphalt made 

 from the same crude at different temperatures. 

 The effect of the character of the crude from 

 which these products are made as influencing the 

 fixed carbon characteristics, and the application 

 of this test to specifications, is pointed out. 



A Method for Determining the Toughness of 

 Bituminous Materials: J. E. Myers, chief chem- 

 ist New York State Highway Department, 

 Albany, N. Y. 



The toughness of bituminous materials is deter- 

 mined by filling a 3 oz. tin box (3.5 cm. deep by 

 5.5 cm. in diameter) with the melted material. 

 The material is allowed to cool to room tempera- 

 ture. When cold the box is held by a pair of 

 tongs, rapidly heated over a Bunseu burner, and 

 the material emptied into a can of cold water. In 

 heating, only enough heat is applied to free the 

 material from the box, so when emptied into the 

 water the material is still solid, being softened 

 only on its exterior. By wetting the hands this 

 cylindrical shaped piece of bitumen is easily rolled 

 into a ball which will be free from seams. 



The ball is maintained at the temperature at 

 which the test is to be made (usually at zero 

 degrees C.) for at least one hour before testing. 

 The balls are tested in the impact machine adopted 

 by the American Society for Testing Materials, 

 for determining the toughness of rock used in 

 macadam roads. The essential working parts of 

 the impact machine are the anvil, of 50 kilograms 

 weight; the hammer, of 2 kilograms weight, and 

 the plunger, of 1 kilogram weight, the plunger 

 having a hemispherical-shaped head of 1 cm. 

 radius. 



In testing asphaltic materials the drop of the 

 hammer is taken from a height of 5 cm. for the 

 first blow and the drop of each succeeding blow 

 is increased 5 em. The height from which the 

 hammer falls when rupture occurs is given as the 

 toughuess of the material. 



Distillation of Tar. Methods of Determination, 

 and Value in Specifi,cations : Philip P. Sharp- 

 LEs, chief chemist, Barrett Manufacturing Co., 

 Boston, Mass. 



