UTAH ACADEMY OF SCIENCES 89 
Rock ASPHALT: 
Practically the only use of this material is in the pav- 
ing industry. According to statements made by the Salt 
Lake City engineering department’s chemist, it would be 
an ideal paving mixture if it could be obtained of uniform 
grade. 
To date the material brought on the market has been 
extremely variable in bitumen content, and until some 
means of supplying a uniform grade is found it can not 
be entirely acceptable as a surface mixture. 
EXPERIMENTAL RESULTS. 
The results of the first tests made on the eight samples 
are given in table one. They are the standard tests recom- 
mended by Richardson and required by the New York test- 
ing laboratory. The tests are meant primarily to determine 
the fitness of the material for asphalt paving. None of 
the samples as they occur comes up to the standards com- 
pletely, but in the case of Trinidad, Bermudez, Gilsonite, 
and Rock Asphalt, the bitumen could be mixed with heavy 
petroleum oil and given the required penetration and other 
properties. As our work was concerned with the properties 
of the materials as they occur in nature no compounding 
was done. 
The hardness is given in terms of the commonly ac- 
cepted mineralogical scale®®. In all cases—as might be 
expected—the hardness is low. 
The streak is the color of the powder or the color of 
the mark made by the material on a piece of unglazed 
porcelain. This was found to be brown in all cases, vary- 
ing from light to dark. 
The specific gravity was determined in two ways. 
First, with the specific gravity bottle and then by weighing 
a sample and finding the increase in volume of water in a 
burette. When the sample is added great care must be 
taken to have no air bubbles adhere to it. The two methods 
8 Tale.—1, Gypsum=—2, Calcite—3, Fluorite—4, a saa idl Orthoclase 
=u Quartz—7, Topaz—8, Sapphire—9, Diamond=10 
