TRINIDAD AND BERMUDEZ ASPHALTS 



177 



Photo, W. H. Rau, Philadelphia. 

 Guanaco River as Viewed riion Pier. 



steam, when the amount of the latter in the chloroform extract which is insoluble 

 in benzol is at least 7.5 per cent, and the asphalt, separated according to the 

 method of Marcusson and Erckmann, contains 1.4-3.1 per cent, of oil with at the 

 most 0.6 per cent, paraffin. 



A bitumen would be called a petroleum residual pitch if it contains at most 

 1.7 per cent, of sulphur, even in the chloroform extract prepared as previously 

 described and further 26-59 per cent, of oil in which the paraffin amounted to 

 3.3-16.6 per cent. 



These conclusions of Holde are confirmed by my own data given in 

 the paper to which I have referred, and are of the greater value on that 

 account. 



It appears, therefore, that a native solid asphalt is characterized by 

 the fact that it contains sulphur, and the same thing is true, though in 

 a lesser degree, of the softer bitumens from which it is derived. 



Aside from the mere fact that sulphur is present in asphalt it is 

 undoubtedly true that some of the most important physical character- 

 istics of the material and those which distinguish it from the residual 

 pitches are due to its presence, that is to say, the greater lack of sus- 

 ceptibility to change in consistency with change of temperature in the 

 solid asphalts than is the case of the residual oils and pitches. 



It is the presence of such a large amount of sulphur derivatives in 

 Trinidad and Bermudez asphalt which makes them so desirable for use 

 in highway construction, as compared with the residual pitches pre- 



