TRANSACTIONS OF THE SECTIONS. 59 
Transactions, that the lapidifying substance is iron, and that, when the petiitication 
is only partial, upon burning such a wood only the petrified part comes'to a glow 
heat, and the ash which is left is attracted by the magnet. Bischof also'madé a 
partial examination of a specimen of the petrified wood, which, however, does not 
sustain his views respecting the ferruginous nature of the lapidifying material, as 
he found it to contain only 0°54 per cent. of oxide of iron and alumina’ o 
The specimen of petrified wood examined by Bischof gave the following results :—= 
Silica .... ey ae ee ee 97-71 i te 
Oxide of iron and alumina ....... i arch ype eestete tS aki ha ates oh SaaS OR ROE eu sats 
PR OURON oi wivins ho aie aa ek wag ng dare sattd Oevaeaaten DOF 
Loss and organic matter ........+..4. said siacaiela Gills auiessiberlgebls oe 
100-00 
On ignition only a. feeble empyreumatic .odour .was perceptible and a slight 
darkening in colour. suet a eens eS 
Immense masses of the petrified wood have been found along the shores of the 
lake. Some of the pieces of wood discovered are of large size ; and one mass, de- 
examination, and also. made analyses of specimens of the. silicified wood. These 
analyses show that in no .part of the.lake does the water. contain any considerable 
amount of solid matter, and that neither in the water nor in the petrified wood is 
to be found more than a very minute quantity of iron. A specimen of the water 
which had been taken at Sandy Bay, 100 yards from the. shore and four miles from 
Glenavy river, near a part ‘of the lake shore in which the petrified wood is fre- 
quently discovered, when received was slightly turbid from. finely. divided floceulent 
matter, and the colour, when viewed through a layer two feet in length, was pale 
greyish yellow. Its taste was soft, and a considerable number of animalcules were 
moving about in it. It had an alkaline reaction. 
~ On evaporation it left a yellowish-coloured residue, which became black on igni- 
tion. | : 
An imperial gallon contained 12:950 grains, consisting of :— 
Mineral and saline matters .......ssseegaeeenene 10:826 grains, 
NON SANIC ANG VOLBOLE! «veo ejereiais vieun cuuraeal die I REE. 2124 >, 
The mineral matters were found to consist of :— 
ter grains. 
Carbonate of lime .......0..0 eee Rn ie PA sd tiFBS 
Parbonatelos MAapNEsi ae.) wjeisisies «asic cole wlolstors ale! siereie)» sine 0-496 
Carbonate of soda ......... TE ot eR ee Ie as 1:088 
Sulphate of soda... .....seeneesees eM Toe er te 1-715 
Oxide Ghirontors yee Oe ee el eee canes s 0:727 
Silicic acid. 0... eVivs towevdee sae ce uk Be RPE RE A ad sels 0:360 
Chloride of sodium.............5- RAR REN Sree cate oopettet G4 
10-826 
The author also determined the amount of mineral matter contained in the water 
at two other portions of the lake. A specimen taken at the mouth of the river 
Bann, which, rising from springs in the granitic range of the mountains of Mourne, 
5% 
