Scientific Intelligence.— Mineralogy. 
191 
ed chemist, specimens for analysis, of several varieties of this 
mineral, and the following is the result of his examination : Car- 
bonate of Lead, 72.7 ; Sulphate of Lead, 27.5 ; = 100.0. 
11. Native Magnesia , or Hydrate of Magnesia. — Dr Ander- 
son also sent, for analysis to Stromeyer, specimens of this mi- 
neral from Swinaness, in Unst, in Shetland. It afforded the 
following constituent parts : Magnesia, 66.67 ; Oxide of Manga- 
nese, 1.57 ; Oxiduleof Iron, 1.18 ; Lime, 0.19; Water, 80.39; 
= 100 . 00 . 
12. Magnesite, from Salem in India. — To Stromeyer we are 
also indebted for the communication of a new analysis of this 
mineral, specimens of which were sent to him by Dr Anderson. 
It contains, Carbonic Acid, 51.827; Magnesia, 47.887; Lime, 
0.286 ; Oxidule of Iron a trace = 100.000. 
13. Olivine. — According to Stromeyer, who has just publish- 
ed an interesting account of his chemical examination of this 
mineral, it contains the following parts : Olivine, from the basalt 
of the Yogelberg, Silica, 40.09 ; Magnesia, 50.49; Oxidule of 
Iron, 8.17 ; Oxide of Nickel, 0.37 ; Oxide of Manganese, 0.20 ; 
Alumina, 0.19 ; =99-51. Olivine of Kasalthof, in Bohemia, 
contains Silica, 40.45 ; Magnesia, 50.67 ; Oxidule of Iron, 8.07 ; 
Oxide of Nickel, 0.33 ; Oxide of Manganese, 0.18 ; Alumina, 
0.19; = 99,89. 
14. Crysolite. — According to Stromeyer the following are the 
constituent parts of this mineral : Silica, 39.73; Magnesia, 50.13; 
Oxidule of Iron, 9.19 ; Oxide of Nickel, 0.32; Oxide of Manga- 
nese, 0.09 ; Alumina, 0.22 ; = 99-68. 
GEOLOGY. 
15. Evolution of Carbonic Acid Gas, at the. Lake ofLaach , and 
in the Volcanic district of the Efel. — The occurrence of spring 
waters, impregnated with carbonic acid, is not very uncommon, 
but the permanent evolution of this gas, from the fissures of 
rocks, is less frequent. Bischof and Noggerath, in Schweigger’s 
Journal, mention a pit, on the side of the lake of Laach, in which 
they found many dead animals, as birds of different kinds, 
squirrels, bats, frogs, toads, and also insects. On descending into 
