286 PHILOSOPHICAL TRANSACTIONS. [aNNO 1746. 



it impossible to fix on the particular place where the petrifying juice most prevails ; 

 except a tree, or any large 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 has endea- 

 voured to prove ; that it is or may be in some peculiar places of the adjacent 

 ground, he grants ; 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 whet- 

 stone kind, and seem to be holly or ash, petrified by some strong nitrous and 

 stony particles ; for, in a solution of it in aquafortis and oil of vitriol, it leaves no 

 tincture, but the liquor growing muddy, like pipe-water after great rains, and there- 

 fore 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 stony 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 cer- 

 tain places, find or force their way through the sand or pores of the earth, they 

 may operate on wood, &c. buried in the ground, permeate its vessels, and by de- 

 grees turn it into stone ; and such is the most probable, if not the only reason, 

 that can be assigned for those petrifications of wood found in sand, as mentioned 

 by Boyle and Plot. 



He received last summer, 1745, from a friend about 30 of these stones, found 

 on the shores of the lake, some in the water, some in the mud, some in the 

 sand, and others in a yellowish clay. That they were petnfied in the lake is 

 probable, but whether in the water, mud, sand, or clay, is no matter ; for cer- 

 tain it is (to use Mr. Smyth's own words), that they were not brought hither 

 from any distance, such as 2, 4, 6, 8 miles, after being dug out of the ground, 

 and then thrown and dispersed on the shores of the lake : and besides, the differ- 

 ence in the colour of these stones, those found in the lake, and those found in 

 the ground somewhat distant from it, is such that they cannot well be mistaken 

 for each other. Those found in the ground are white, and of a looser texture ; 

 those found in or on the shores of the lake are black, closer, and heavier. That 

 these last were petrified by a mineral spring, appears from the few following ob- 

 servations. — They do not ferment with acids, spirit and oil of vitriol. The solu- 

 tion of this stone in aquafortis gives a beautiful red tincture, and in oil of vitriol 

 leaves a tincture of a brown dark red. The woody part of these stones in aqua- 

 fortis also gives a red tincture, though somewhat paler; and, when taken out of 

 the liquor, shows red spots in its pores, which he takes to be particles of iron and 

 sulphur: these spots, when the wood began to dry, became black; and the wood, 

 when dry, turned of the colour of a deep red Jesuit's-bark. 



• Philos. Trans. N° 59.— Orig. 



