254 YEAR- ROOK OF FACTS. 



were next considered ; and the innutritions nature of gelatine, and 

 the danger of confining diet to that substance, were pointed out. 

 The lecture was concluded by an account of the manufacture of gold- 

 beaters' skin, catgut, and silkworm-gut, from the membranes of 

 the stomach of the sheeji, &c. — Illustrated London New. 



METAMORPHISIT. 



The production of crystalline rock forms the subject of an ela- 

 borate article in a recent Number of the Annates des Mines, by M. 

 Daubree, which contains an interesting account of his own expe- 

 riments, and a rSsumS of the researches of other eminent mineralo- 

 gists, with details of the artificial formation of precious stones, &c. 



LOSS OF THE PRECIOUS METALS IX ASSATIWG. 



Ma. G. Makins (in the Journal of H al Society) 



how small quantities of Geld and Silver are lost by volatilization in 

 the flues, and by dissolution in the nitric acid employed. These 

 small quantities, as he states, become important in the vast amounts 

 which are passing through the hands of the assayer. 



"silver spring'' is Florida. 

 Professor John Le Conti: has read to the American Association 

 a paper on the Phenomena presented by the " Silver Spring" in 

 Marion County, Florida. Although the optical phenomena of this 

 Boring had been greatly exaggerated, yet he found, on paying it a 

 visit last December, that it was sufficiently wonderful. Whileit was 

 reported to be 200 feet deep, a careful measurement showed it to be 

 only 30 feet, <bi a clear and calm day. the view from the side of a 

 boat is beautiful beyond description. Every feature of the bottom 

 is as clear as if there were DO water above it, but only the clear air. 

 The bottom is thickly covered with luxuriant vegetable growth, de- 

 veloped by the large amount of BUnlight which penei 

 Objects beneath the surface' of the water, viewed obliquely, Appear 



surrounded by prismatic hues. The beholder seems to be looking 

 from some bigb point, upon a truly fairy scene. Large letters 



at the bottom can be read from the surface of the well as if they 

 in the open air. Small letters cannot lie read so easily, 



because the BUlface is not entirely quiescent. 



OBOUHD-K i'. 



\I. I'.ni.i i.hakut has repeated his experiments made in 

 with a view to explain the formation of Ground- fee. 



[n conclusion, the author attributes the formation of 

 to obstacles in the current, which, on the one hand, by the eddying 

 motion, cause the water I" '"V. to link to the bottom and i 1 the 



side-, and on the other hand, produce stationary parts in which the 



dlizing powi r ' an i red the infl 



in a conduit at Zinswcilei. In 1829, ice 



■..in of the water is which there were 1 

 i ition of io < ly prevei 



