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to make into kelp (formerly used as an alkali in the manu- 
facture of alum) that they frequently collected and brought 
a bag of jet home to burn, there were such quantities at 
that time on the beach, undoubtedly produced by the washing 
away of the cliffs for centuries. Those individuals affirm 
that no coals are equal to it for making a good fire. The 
origin of jet is held as a matter of doubt, but the prevailing 
opinion is that it is of vegetable origin — fossil wood in a high 
state of bituminization, and I have no doubt but this is 
correct. I have observed in Kettleness Alum Works pieces 
of lignite, weighing two to three hundred weight, completely 
encrusted with jet, about half an inch in thickness ; but, on 
becoming exposed to the air a few months, the jet falls off, 
leaving the lignite perfectly clean, and in a high state of 
preservation. Although I have never observed the real hard 
jet of the lias having a ligneous structure in the strata where 
it is found, nor have I observed any lignite encrusted near 
so low down as the jet lines ; but the fact of having found 
lignite encrusted with jet (and even jet in a soft state, 
as if forming) in working the alum shale 90 to 100 feet 
above the jet lines, has led me to the conclusion that those 
jet seams lower down are nothing more than the lignite 
found above, dissolved and reformed by the agency of the 
more powerful sulphurous and bituminous gases of the jet 
shale. The chemical composition of the lias shale varies 
considerably, the top part containing a large per-centage of 
alumina and magnesia ; but as you go deeper in the lias 
those ingredients decrease, and the shale becomes so highly 
impregnated with sulphur and bitumen, that by the time 
you arrive at the jet shale, such is the per-centage of those 
ingredients, it is not at all uncommon after wet weather 
that this shale will ignite spontaneously and burn for 
months. The manufacture of jet ornaments must, in some 
measure, be regarded as the staple trade of Whitby at 
