234 



ASPHALTE. 



with it at the same time ten per cent, of pitch 

 after which it is to be spread on the stone or 

 wood to be coated, previously heated to a slight 

 degree. 



Such was the first attempt made, in modern 

 times, to turn the natural production called as- 

 phulte to service in building. Eirinis was not 

 supported properly, however, and the Vul de Tra- 

 vers mines, though occasionally wrought by suc- 

 ceeding speculators, have only fallen into compe- 

 tent bands within a very recent period. Count de 

 Sassenay, who had acquired the requisite experi- 

 ence by his having been for six years the proprietor 

 and manager of the Seyssel mines, became, in the 

 beginning of 1838, the proprietor of those of the 

 V:illey of Travers in Neufchatel. The Seyssel 

 mines, it is to be observed, are also asphaltic, and 

 had been wrought for a number of years. But, 

 on examination, Count de Sassenay found the 

 Neufchatel mines to contain a finer-grained rock, 

 and with two per cent, more of bitumen in it, 

 than the Seyssel mines. He was therefore led to 

 become the purchaser of the former, and has esta- 

 blished a company at Neufchatel, with a capital of 

 forty thousand pounds, for the working of as- 

 phalte, and for its sale in the various countries 

 around. 



Count de Sassenay states, in the Introduction 

 to a little pamphlet which supplies us with these 

 particulars, that there are two kinds of mineral 

 matter which go by the name of asphalte, though 

 erroneously so. The first is an earthy concretion 

 of gritty, loose texture, to which the count gives 

 the name of bituminous molasse, and which he as- 

 cribes to the latest or tertiary formation of rocks. 

 The other substance is the true asphalte, which is 

 solid, of the colour of soot, and is an admixture of 

 bitumen with calcareous or limestone rock of the 

 Jura formation, which belongs to the secondary 

 era. The bitumen is here completely combined or 

 amalgamated with the calcareous material, and this 

 union is productive of a new homogeneous sub- 

 stance, which alone is the true asphaltic cement, 

 or asphalte. Bituminous molasse is a mineral 

 substance comparatively abundant on the continent, 

 and has been wrought in several places with the 

 view of making the same cement, but has not un- 

 dergone that natural admixture with calcareous 

 matter which constitutes the true asphalte, and 

 hence such views have not been realized. This is 

 not only stated by Count de Sassenay, but by M. 

 Rozet, M. H. Fournel (a noted engineer), and 

 other observers. " Many experiments have been 

 made to imitate the cement we have mentioned 

 (that of Seyssel) ; but in these operations the 

 want of the calcareous matter has been attempted 

 to be supplied by substances, which, absorbing the 

 bitumen, produce a composition which cannot re- 

 sist the influence of heat or cold, but is melted by 

 the sun and cracked by the frost." The Val de 

 Travers, where are found the finest kinds, as has 

 been said, of this natural production, formed in all 

 probability under strong volcanic action, leads into 

 the Lake of Neufchatel. Half way up the moun- 

 tain-sides, the asphaltic works are carried on. 

 " The operations," says M. Fournel, " are very 

 simple, and consist merely in blasting the rock. 

 The cavities for the powder are perforated by 

 wimUes of about thirty-nine inches in length, one 

 of which a man can work as he would a carpen- 

 ter's auger. This manner of boring appears to he 

 applicable only to the asphaltic stone. The 



labourers can work better in winter thm in sum- 

 mer ; because the rock being harder and more con- 

 densed in cold weather, the powder has more effect, 

 and the blasting is more extensive." The rock is 

 in blocks or irregular masses, not in strata, and 

 there is reason to believe that the whole mountain 

 is of asphalte. The manner of preparing the rock 

 for cementing purposes is this. " Ninety-four parts 

 (weight) of the asphaltic stone, pulverised, are 

 mixed with six parts of bitumen, mid melted down 

 in large boilers; and the mass is then poured off 

 and formed into rectangular cakes, which are sold 

 as the asphaltic cement." It is easily re-melted, 

 and instead of losing, gains quality by the repeti- 

 tion of the process. Of late, however, the plan 

 has been adopted of sending the stone itself to the 

 place where it is to be used, and there melting 

 mid mixing it with the tar immediately before une,. 

 This saves one melting. The way of using it re- 

 quires little explanation. When melted, the ce- 

 ment is merely spread over the desired part equally, 

 and in such thickness as circumstances may re- 

 quire. In the coating of places to be trodden 

 much, such as footways, terraces, slabs, &c. it is 

 customary to mix fine river sand with it, which 

 gives it more stability, and a degree of roughness 

 that is not unnecessary. 



We have now to ask if the asphaltic cement 

 has been extensively tried, and with what issue. 

 Count de Sassenay, when proprietor of the Seyssel 

 mines, obtained permission to use the cement in 

 the fortifications of Vincennes, Douay, Grenoble, 

 and Besanfon. The minister of war was satisfied 

 by the experiment that it would be highly advan- 

 tageous to have the roofs, floors, &c. of barrack- 

 rooms coated, both on the score of cleanliness 

 (inasmuch as the cementing was easily washed), 

 and on account of the protection against damp af- 

 forded by it. It was also found that rats and rriire 

 disappeared where the cement was laid down. On 

 these facts being ascertained, the Freiich minister of 

 war contracted for the use of asphalte in the va- 

 rious buildings over which he had control. The 

 extensive commissariat magazines at Bercy, and 

 those which supply the garrison of Paris, the roots, 

 ceilings, and floors of the detached forts at Lyons, 

 the arsenal at Douay, the new barracks at Peronne, 

 those at Mont Louis and other places, were all 

 supplied with asphaltic coatings, in whole or in 

 part. Asphalte was also substituted for the stone 

 pavement in some of the cavalry barracks. The 

 unwearability of the material rendered these ex- 

 periments most satisfactory. [A staircase, coated 

 with the cement by Eirinis more than a hundred 

 years ago, still remains, and is unmarked, whereas 

 contemporary stow stairs in the same building are 

 hollowed out by foot-marks.] The ministers of 

 the Marine and of the Interior in France followed 

 the example of the War Minister, and coated their 

 convict-prisons and other edifices with the asphalte, 

 and with equal satisfaction. 



These things passed very recently subsequently 

 indeed, to the year 1832 when Count de Sasse- 

 nay became proprietor of the Seyssel mines, from 

 which the asphaltic cement was procured for the 

 purposes mentioned. It was not till 1835 that any 

 experiment was made upon the use of asphalte 

 for flagging thoroughfares. At that time the foot- 

 way of the Pont Royal was coated with the ce- 

 ment, and its durability, under the tread of thirty 

 thousand people daily, has amply justified the trial. 

 Since that time, the footway of the bridge Du 





