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the argillaceous ores of the lias. Its principal advantage is 
on account of its being more easily fluxed in the furnace. 
10. Upper Lias. — Consisting of aluminous shale, cement 
stone, ironstone, nodules, &c. From this shale the Whitby 
alum has been made for centuries. The upper part is used 
for this purpose on account of its containing a greater per- 
centage of sulphate of alumina and magnesia, and being 
more free from iron, which is injurious to the process. The 
Mulgrave Alum Works, which have been so long carried on, 
are the largest on the coast, and are situated at Sandsend and 
Kettleness, three and six miles north of Whitby. They 
manufacture, when in full operation, at these two works 
about 150 tons of alum, and 120 tons of rough sulphate 
of magnesia (Epsom salts), monthly. I will endeavour to 
give a short description of the process, which runs as follows, 
viz. : — First, the shale is worked and broken up into pieces, 
say fourteen pounds weight, run into heaps containing many 
thousand tons, always having refuse wood, faggots, &c, 
placed at the bottom of the heap, and in a proper position for 
burning the same. When the fuel is fired, there is sufficient 
bituminous and sulphurous matter in the rock to calcine it. 
The calcined mine is then lixiviated with water in large pits. 
The liquors are then taken and evaporated down to a certain 
specific gravity, and an alkali added, generally sulphate of 
ammonia, — then run into large vats or coolers, and allowed 
to stand six days to crystallize the alum. The crystals are 
then taken out, washed, then dissolved again in water, and 
run into large casks to re-crystallize ; after that broken into 
large lumps, or ground according to the requirements of the 
markets. It must be remembered that the sulphate of mag- 
nesia is held in solution during the cr3 7 stallization of the alum, 
and evaporated again to a higher specific gravity, then run 
into vats and crystallized in the same way as the alum. 
In working the alum shale, large quantities of cement and 
