SUPPLEMENTARY NOTES. 



447 



Similar experiments were repeated on a larger scale, by Mr. 

 Gregory Watt, in 1804. Sir James Hall's experiments on repro- 

 ducing artificial limestone and crystalline marble, were made 

 in 1805. 



Mr. Whewell, in his Report on Mineralogy to the British Asso- 

 ciation at Oxford, 1832, refers to observations of Dr. Wallaston 

 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 

 Repetli. 



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 

 f'g- of an inch in length, and y\ in diameter, and readily scratching 

 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. .58, 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 farther shown that the Coal 



