356 



ALUM MINGS OF AUBIN. 



Th« mine of 

 Xassalle. 



Burning t>iese 

 twenty years. 



The fire now 

 abating. 



Mine of Fon- 

 laines. 



Has burned 

 these 80 yeart 

 in different 

 scams. 



silkj masses, in yelloivish mamillarjr incrustations, or ia 

 confused masses, friable, cavernous, white, gray, yellow, 

 red, or a mixture o^ all these colours. It may not be su« 

 perlluous to add^ that the last variety is sometimes met 

 with in blocks or incrustations weighing several pounds. 



Such are the general characters of these alum mines, but 

 there are particular ones, which ought to be noticed. 



The alum mine of Lassalleis in the bottom of a valley, 

 at the foot of the hill of the same name, two miles north by 

 west from the town of Aubin. The surface it occupies on a 

 slope of about 45**, does not amount to 2 hect. [247 acres]. 

 The subterranean fire has not exceeded the limits of the coal- 

 pit: it occupies the length of 250 met. [273 yards] at the 

 foot of the mountain, and extends nearly 70 met. [78 

 yards] into it. It has attacked nothing below the level of 

 the brook, that flows through the valley. 



This pit took fire spontaneously about twenty years ago. 

 The stratum of coal, which feeds it, was three or four yards 

 thick, and worked by means of levels. Attempts were made 

 to extinguish the fire at the time, but in vain. The inclina- 

 tion of the strata in this part of the mountain is about S*' or 

 10° W. N. W. ; or contrary .to the slope of the mountain. 



The activity of the fire has decreased greatly within these 

 few years. It appears to be drawing to an end ; or that 

 the accumulation of torrefied and decomposed substances, 

 that cover the surface, has retarded its ravages. The effect 

 of the exavations made within these six months seems to 

 confirm the latter opinion. Vapours now issue out abun- 

 dantly by all the new vents they have been able to make, 

 and the saline efflorescences increase more rapidly. 



Thisinine has not been worked above nine months. 



The alum mine of Fontaines is at the bottom of the cul- 

 de-sac, that terminates Ihe valley of Lassalle, and at the 

 foot of the mountain 2500 met. [2732 yards] N. E. of 

 Aubin. It takes its name from a hamlet directly above it. 

 Its surface is nearly square, and may be 3 hect. [370 

 acres]. The foot of the mountain at this place has a slope 

 of about BO''. 



The fire commenced here eighty years ago. Several 

 teams of coal were then working, one oTer another, and 



inclining 



