ALUM MINE. 233 



XIII. 



Some Jccoimt of a very singular and important Alum Mi7ie near 

 Glasgow, at present worked by Messrs. Mackintosh, Knox, 

 and Co. Taken by Dictation Jrom Mr. Kn ox, ^3/ the Editor. 



.T Hurlett, near Glasgow, the works of Messrs. Mackin- Wonderful ex- 

 losh, Knox, and Co. the aluminous schistus lies 10 inches thick ^^^vation of a 

 above a coal, at all distances from the day. It is at r^resent "''^^ '" ^''^^"^' 

 worked at the depth of 30 fathoms over a coal-pit worked for 

 three centuries, and now in work. The dip is just sufficient 

 to keep the whole excavation quite drf; and the schisdis above 

 becomes decomposed by oxigenation, and falls down* in con- 

 sequence of the working maintained during that long series, ' 

 constantly in the same apartment and at the lowest point. The 

 excavation is now at the prodigious dimensions of a mile in 

 length, and little less in breadth. The coal stratum thus taken 

 out, is very regularly 5 feet thick. About the year 1620, a ""f^'"^^^ ^"^'" 

 tack or lease still extant, describes it as an extensive going *^" '^' 

 work; and particular precaution is taken lest the tenant should 

 work the whole of it out. It is upon the estate of the Earl of 

 Glasgow ; and the schistus is the same as is alluded to by Dr. 

 Black in his lectures. The alum wo>k is perhaps the largest 

 single work in Great Britain, and probably in the whole world ; 

 and this article being now-eqiial in quality to that of Italy, is 

 exported to foreign parts instead of our manufactures being 

 dependant on supplies from abroad as formerly. 



The whole roof of this immense cavity being exposed to the Curious and 

 atmospheric air, is in a slate of gradual decomposition. This <^xtensive oxi« 

 process is so slow, that in the long period of time before men- ^^"^''°"' 

 tioned, the full roof of 10 inches is in no place gone. It flakes 

 off by the oxigenation, and fails down ; in which last situation, 

 the oxigenation goes on upon the dry floor, and swells up the 

 mass of a fine light spicular efflorescence to the height of three, 

 four, and even the whole five feet of the excavation. 



The combination of circumstances in this work, are very ex- s'n ! 

 traordinary. Had the schistus been disposed on the floor, in- blnSion o'Sr- 



stead '"'""'"'^'• 



* In the coal excavation, one-fourth has been left as pillars to sup- 

 port it. They are round, and about 1 8 feet diameter. 



