332 ' KANSAS CITY REVIEW OF SCIENCE. 



A careful observation of asphaltic formations has led me to adopt what appears 

 to me to be a more plausible theory. 



It is permitted to suppose, from indications furnished by the study of bitum- 

 inous districts, that in some geological epochs, which have yet been only imper- 

 fectly determined, accumulations of organic matter, buried under enormous 

 masses of Jurassic limestone, and heated by the central fire, became vaporized, 

 and in that condition sought a passage through the crust of the earth. In time the 

 crust cracked, and a fissure was formed. The bituminous vapors, compressed 

 by incalculable pressure, forced themselves through the way that was opened to 

 them, and passed by such strata as were too compact to be penetrated ; but, 

 when they reached the oolite, they found on either side of the fissure, beds of a 

 limestone soft enough to admit of their impregnating it. As long as the pressure 

 lasted, the bitumen continued to insinuate itself through the pores of the lime- 

 stone, and to fill its infinitesimal cavities. 



Mineral asphalt is relatively a soft stone. It becomes more compact as the 

 temperature diminishes, but yields under the influence of heat to such a degree 

 that an exposure of a few days to the summer sun will sometimes cause it to 

 crumble. This property has induced the application of the compressed material 

 to the making of pavements. Its fitness for this purpose seems to have been 

 suggested by accident. When the mineral was first quarried, the pieces which 

 fell along the »road from the wagons carrying it were ground up by the wheels, 

 and were finally compressed again by the continued passage of the wagons 

 over the dust, so far as to form a kind of spontaneous pavement. A Swiss en- 

 gineer, M. Merian, acting upon the suggestion of this incident, asphalted a 

 part of the road from Travers to Pontarlier, in a rough way, but with a "satis- 

 factory result. In the next year (1850), M. Darcy, inspector-general of bridges 

 and highways, recommended asphalt as a material for pavements in a report to 

 the Minister of Public Works. The first asphaltic pavement was laid in Paris 

 in 1854. 



The mineral appears in industry, under a still more useful form than the 

 compressed form, as asphaltic mastic. This is made by throwing the powdered 

 mineral into a bath of seven or eight per cent, of its weight of liquid bitumen, 

 and mixing the whole thoroughly while it is cooked for five or six hours. The 

 substance produced, although chemically the same, except for the difference in 

 the relative proportions of bitumen and limestone, is physically entirely different 

 from asphalt. It cannot be pulverized by heating, but forms a paste in which the 

 two ingredients seem to be perfectly combined, and which may be molded into 

 desired forms. The manufacture of the mastic has become an important indus- 

 try. The annual production of the French shops alone must amount to fifteen 

 or twenty thousand tons. 



In "La Nature," of April 9th, Mr. A. Woeikofen, of St. Petersburg, de- 

 scribes the asphaltic beds of Russia, which occur on the grand curve of the Volga, 

 or the arc of Samara, a short distance above the city of Syzran. They are not 

 deposited in the Jurassic formation, as are those in France, Switzerland, and 



