1818.] Analyses of Boolcs. 133 



indebted to M. Gay-Lussac. In order to verify it by experi- 

 ment, it is sufficient to put distilled water into a glass vessel, 

 and cause it to boil ; it will be perceived to boil by starts and 

 with difficulty. Remove it from the fire, by which we must 

 certainly lower its temperature ; and after an interval of some 

 seconds, throw into it a small quantity of iron filings ; the fluid 

 will instantly be thrown into a state of complete ebullition. 

 These different operations must, however, necessarily tend to 

 lower its temperature, and consequently the throwing in of the 

 iron filings must have exercised upon it some unknown action 

 which facilitates its ebullition. 



" This is the general fact : in order to ascertain its degree, 

 M. Gay-Lussac observed the temperature of the water the 

 moment when it began to boil in a glass vessel ; he found it to 

 be 214-2 Fahr. (101-232 cent.) If we throw into the vessel finely 

 powdered glass, the temperature of ebullition descends to 212-6 

 Fahr. (100-329 cent.); if we put iron filings into it, the temper- 

 ature descends still lower, and becomes stationary at 212 Fahr. 

 (100 cent.) M. Gay-Lussac also found that the size of the 

 vessel has no influence upon the phenomenon, nor had the 

 greater or less quantity of the iron filings any effect ; water 

 heated in a metallic vessel boiled at 212 Fahr. (100 cent.)" — 

 (Biot, Traite de Physique, i. 42.) 



Article XV. 



Analyses of Books. 

 Transactions of the Geological Society, Vols. III. and IV. 



{Continued from Vol. x\. p. 453.) 



III. — 2. On the Oxide of' Uranium, the Production of Cornwall, 

 together with a Description and Sei-ies of its crystalline Forms. 

 By Mr. W. Phillips. 



In this paper Mr. Phillips describes the varieties of uranite 

 which have lately been found in Cornwall. This mineral had 

 been observed to occur rarely in the mine called Carharack, 

 accompanied with iron ochre, and cubic arseniate of iron. In 

 1805, Mr. P. discovered uranite atTincroft mine, near Redruth, 

 accompanied by pulverulent pecherz, and at Tol Cam mine, about 

 two miles north of Carharack, also accompanied by pecherz. 

 The most beautiful specimens of this substance, however, have 

 recently been discovered in Gunnislake copper mine, near Cal- 

 lington. The acuteness of Mr. P. has detected a considerable 

 number of new crystalline varieties among his specimens of 

 Cornish uranite, which are described in this paper. 



III. — 6. Outlines of the Geology of Cambridgeshire. By the 



