238 Scientific Intelligence. [Sept. 



alumina is considerable. The following is the result of an 

 analysis of a specimen of clay iron-stone from Colnbrook-dale: — 



Silica 10-6 



Alumina 2*0 



Lime 1*6 



Magnesia 2 - 4 



s Oxide of iron . . 500 



Oxide of manganese 2-6 



Loss by calcination 32 



101-2 



See an essay on this species of ore, by Descotils, in the 

 Annates de Chimie, Ixxxiv. 188. 



V. Peroxide of Lead. 



A phenomenon lately occurred to Chevreul which deserves 

 to be recorded. He was employed in analysing a specimen of 

 crystal glass, and for that purpose fused it in a platinum crucible 

 with potash. When the process was finished, he found in the 

 crucible an alloy oflead and platinum, and a quantity of per- 

 oxide of lead, mixed with the other ingredients in the fused 

 mass. 



VI. Subsulphale of Alumina. 



In Vol. I. p. 467, of the Annals of Philosophy, mention was 

 made of specimens of pure alumina found by Mr Webster, 

 between Brighton and Beachy head. Specimens have been 

 since brought to London by Mr. Tennant, and the substance 

 has been more carefully examined by Dr. Wollaston and Mr. 

 Smithson, and both have found it to be not pure alumina, but a 

 subsulphate of alumina. 



Article XIII. 



Scientific Books in hand, or in the Press. 



Dr. Hodgson will publish, in October, a Treatise on the Diseases 

 ©f Arteries and Veins, comprising the Pathology and Treatment of 

 Aneurisms and Wounded Arteries. The Work will consist of One 

 Volume, 8vo, illustrated by a Series of Engravings in 4to. 



Dr. Hutton has nearly ready for publication a Second Edition of 

 Recreations in Mathematics and Natural Philosophy, in four 8vo 

 Volumes, with nearly 100 4to plates. 



Dr. Hales' New Analysis of Chronology, with a copious General 

 Index will appear early in the Winter. 



