CATARACTS, AND INUNDATIONS. 279 



. That such springs tliere are, hidden under the water or mud of 

 this li, will appear probable, from what has heen said, and per- 

 haps evident, from the accounts since received, that in the great 

 frost of 1740, the lake was frozen over so as to bear men on horse- 

 back, yet several circular spaces continued unfrozen. But how 

 several attempts, made, as mentki>e ! , by Messrs Molineux, Ne. 

 vil. and Smyth, to procure wood halt petrified (by fixing stakes of 

 holly in the lake, which received no alteration) proved unsuccessful, 

 the reason i think is plain, because tl*ey were not fixed in the pro- 

 per place, viz. the course or vein of the spring, where nothing but 

 chance could have direct<ed them. This petrified wood is often 

 found in different places on the siaores of the lough, but generally 

 in greater plenty when the water has been disturbed by ?;reat 

 storms; which makes it impossible to fix on the particular place 

 where the petrifying juice most prevails; except a tree, or any 

 larger piece, should be found so fixed as to resist the force of 

 the waves. 



That this petrific quality is in some peculiar parts of the lake, he 

 lias endeavoured to prove ; that it is or may be in some peculiar 

 places of the adjacent ground, he grants 5 though as yet he could 

 not procure any of those stones found in the ground, with wood 

 continuous. Such as he has seen, are of the white whetstone kind, 

 and seem to be Imlly or ash, petrified by some strong nitrous and 

 stony particles : for, in a solution of it in aquafortis and oil of vi- 

 triol, it leaves no tincture, but the liquor growing muddy, like 

 pipe-water after great rains, and therefore shows that they are not 

 so strongly impregnated with metalline particles, as those stones 

 found in or on the shores of the lake. 



Mineral streams or exhalations, being highly saturated with 

 sto.ny and mineral particles, are often found to have a petrifying 

 virtue, as is seen at the bath called Green Pillars * in the city of 

 Buda in Hungary. If such streams should, in certain places, find 

 or force their way through the sand or |K>res of the earth, they may 

 operate on wood, &c. buried in the ground, permeate its vessels, 

 and by degrees turn it into stone ; and such is the most probable, 

 if not the only reason, that can be assigned for those purifications 

 af wood found in sand, as mentioned by Boyle and Plot. 



* Philos. Trans. No. 59. Orig. 

 T 4 



