SUPPLEMENTARY NOTES. 599 
ciation at Oxford, 1832, refers to observations of Dr. Wollaston 
and Professor Miller on crystals of Titanium, and Olivine, found 
in the slag of Iron furnaces ; and to the experiments of Mits- 
cherlich and Berthier on artificial crystals, similar to those found 
in Nature, obtained by them in the furnace by direct synthesis, 
regulated by the Atomic Theory. With respect also to artificial 
crystals obtained in the humid way, he refers to the observations 
and experiments on artificial salts, by Brooke, Haidenger, and 
Beudant, and to the experiments of Haldat, Becquerel, and 
Repetti. 
At the meeting of the British Association at Bristol, August, 
1836, Mr. Crosse communicated the results of his experiments 
in making artificial crystals by means of long continued galvanic 
action, of low intensity, produced by water batteries on humid 
solutions of the elements of various crystalline bodies that occur 
in the mineral kingdom ; and stated, that he had in this way 
obtained artificial crystals of Quartz, Arragonite, Carbonates of 
Lime, Lead, and Copper, and more than 20 other artificial 
minerals. One regularly shaped crystal of Quartz, measuring 
-/^ of an inch in length, and -J-^ in diameter, and readily scratch- 
ing glass, was formed from fluo-silicic acid exposed to the electric 
action of a water battery from the 8th of March to the latter end 
of June, 1836. 
P. 65, Note. In the note respecting the Fresh water shells 
which occur in the upper region of the great Coal formation, I 
have omitted to refer to an important discovery of Mr. Murchison, 
(1831-32), who has traced a peculiar band of limestone, charged 
with the remains of Fresh water animals, e.g. Paludina, Cyclas, 
and microscopic Planorboid shells, interposed between the upper 
Coal measures, from the edge of the Breiddin hills, on the N. W. 
of Shrewsbury, to the banks of the Severn, near Bridgnorth, a 
distance of about thirty miles ; and has further shewn that the 
Coal measures, containing this " lacustrine" limestone, pass up- 
wards conformably into the Lower New Red Sandstone of the 
central counties. (See Proceedings Geol. Soc. V. i. p. 472.) 
The chief localities of the Shropshire limestone are Pontesbury, 
Uffington, Le Botwood, and Tasley. 
