288 PHILOSOPHICAL TRANSACTIONS. [aNNO 17 46. 



saline parts of the petrescent juices that filled the outward pores of the stone, or 

 coagulated on it. This white part scraped, and put into a crucible in a violent fire, 

 could not be reduced to lime, though it grew red as coal. This powder calcined 

 appeared through the microscope quadrangular, like grains of salt ; which made 

 him suspect, that these petrifications contain, besides metalline, a great deal of 

 saline particles, whose sides being strongly attracted to each other, and closely 

 joined, hinders the fire from expanding the pores of these stones, and their being 

 raluced to lime. This black stone, when broken, appears through the micros- 

 cope very beautiful, and like cloth of silver, the pores and vessels of the wood 

 being filled with white minute crystals. 



Of these stones Mr. S. had some with wood outwardly continuous ; others 

 with wood inwardly ; one, the least part is of stone, the rest wood ; another vice 

 versa ; another entirely wood, except a thin coat of stone on one side, which ap- 

 pears to be the very bark ; one stone which at one end distinctly shows the annual 

 ringlets of the v/ood ; one that shows the wood, before it was petrified, had been 

 bent, and partly broken, the fissure being filled with a sparry matter, and appears 

 plainly from the present appearance and position of the fibres of the stone. Some 

 of these stones strike fire with a steel, and others, by a strong collision, emit a 

 train of sparks. Some of these stones show the grain of holly, ash, and fir. He 

 had only one piece of oak petrified, easily distinguished by its grain ; it shows the 

 very knots of the wood where young twigs were cut; and has a hole made through 

 it before it was petrified. 



As for these stones being fit for sharpening or setting of razors, &c. the black 

 ones are rather too hard, and the white ones too soft. The whetstones or hones, 

 vulgarly so called, which are sold for Lough-Neagh stones, are none of these, 

 but of a soft gritty kind, and found near Drogheda. 



When these stones with wood continuous are taken out of the water, mud, 

 or clay, the woody part dries, cracks, and falls away ; which is the reason why 

 few can be well preserved; and besides, every body, unwilling to trust their eyes, will 

 touch and scrape the wood, and thus destroy the most curious part of the stone. 



On the same Subject. By the Right Rev. Dr. George Berkeley,* Lord Bishop of 



Cloyne. N° 481, p. Z15. 



Mr. Simon seems to put it out of doubt, that there is a petrifying quality 

 both in the lake and adjacent earth. What he remarks on the unfrozen spots 

 in the lake is curious, and fi.irnishes a sufficient answer to those who would deny 

 any petrifying virtue to be in the water, from experiments not succeeding in some 



• Bishop Berkeley was celebrated for his religious, moral, and metaphysical writings, of which 

 an account is to be found in numerous biographical publications. He also wrote a Treatise on the 

 Virtues of Tar Water, which he recommended with much enthusiasm in scorbutic and other ca- 

 chectic disorders. He was bom at Kilcrin, in Ireland, l684, and died at Oxford in 1753, ,,..,. 



