610 THE POPULAR SCIENCE MONTHLY. 



to be so friable that in a short time the ordinary travel on the streets 

 reduced it to a fine, black powder, which, in dry weather, was thrown 

 up in murky clouds by every passing vehicle and every gust of wind, 

 finding entry into the adjacent houses through the minutest crevices, 

 and in wet weather was kneaded into a nasty, viscous mud. Soon the 

 streets thus paved were impassable, and the commissioners were forced 

 to order the removal of what was left of the " poultice " pavement. 



This experience was not well calculated to conciliate public opinion 

 in favor of asphalt as a material for paving ; and, though travellers 

 returning home from Paris were loud in praise of the asphalted road- 

 ways of that capital, contrasting the roar of our granite-paved, filthy 

 thoroughfares, with the smooth, noiseless, cleanly streets of the French 

 capital, they were listened to with incredulity. Their " odious com- 

 parisons," instead of causing us to envy the Parisians for their happy 

 solution of the great question of pavements, had only the effect of ex- 

 citing compassion for the poor outside barbarians who put their trust 

 in asphalt. For, had we not tried asphalt here, and found it wanting ? 



Yet it was not the asphalt pavement at all which proved a failure 

 in these experiments. The material used was a spurious compound ; 

 a mixture of sand and gas-house refuse, which had this only in com- 

 mon with asphalt, that the two substances went by the same name. 

 Here the adage, " Give a dog a bad name," was reversed. The genuine 

 asphalt pavement was thus involved in the ill-fortune of its base 

 counterfeit ; only for a little while, it is to be hoped. So soon as we 

 discover within convenient distance from our centres of population 

 native deposits of asphalt, we shall avail ourselves of the improve- 

 ments introduced into the art of road-making in France, and the " com- 

 ing man " can go about his affairs without having his ears stunned by 

 the clatter and roar of vehicles ; the horse of the future perform his 

 service without constantly risking life and limb ; and the carriage of 

 the future roll along without being jolted to pieces. In France the 

 asphalt pavement is as much a success as the railway, and, as we are 

 still seekers, still experimenters in this matter, it is perhaps well that 

 we learn the processes followed by French engineers. 



Dr. L. Meyn, of Halle, has published a pamphlet on "The As- 

 phalts," which sums up all the information that is accessible regarding 

 this material. In the present paper we propose to give, mostly in his 

 own words, the history of asphalt as a material for paving foot-paths 

 and roadways. 



Natural asphalt, or asphalt-stone, is a porous, calcai*eous rock, satu- 

 rated with bitumen, or natural tar, and capable of being worked into 

 a tough, hard mastic. It is not unlike mortar in general appearance, 

 and its color is usually chocolate, giving a fracture of lighter color. 

 Its grain is fine, and each molecule of limestone is coated with the bit- 

 umen. The proportion of the latter in the mass varies from 7 to 15 

 per cent. At a temperature of between 338 and 356 Fahr., asphalt- 



