526 GEOLOGY AND MINERALOGY. 
as compared with the absorptive powers of even the hardest rocks and minerals 
Certain feldspars, for example, became hydrated, in M. Durocher’s experiments, 
to the extent of 0-0041, others to the extent of 00077, &c., and some even to 
that of 0°0269. In sandstones, limestones, and other ordinary rocks, the absorp- 
tion is, of course, very much greater than this. The water absorbed would 
gradually produce, it is considered, definite hydrated compounds, and so remain 
fixed, more especially as the earth’s internal heat became more and more dimin- 
ished. With regard to the probable absorption of the atmosphere, M. Semann 
enters into computations of a similar character, basing his views, as far as pos- 
sible, on the actual results of experimental inquiry, and bringing forward in this 
connexion many collateral questions of much geological interest. Our present 
limited space forbids, however, a more extended analysis of this important 
memoir. 
ON THE SUPPOSED RELATIONS BETWEEN THE ROTATION OF THE EARTH AND THE 
GYRATORY MOVEMENTS WHICH TAKE PLACE IN LIQUID BODIES UNDER CERTAIN 
CONDITIONS. 
In the Comptes Rendus (Tome xlix., p. 637) M. Perrot inserted a note, previously 
read before the Académie des Sciences, on the gyratory movements of water flow- 
ing through a circular aperture at the bottom of the enclosing vessel, in which 
he maintained that this movement (in the northern hemisphere) always took 
place from left to right, a peculiarity due to the diurnal movement of the earth. 
This view being opposed to the researches of M. Magnus, published at length in 
Poggendorf’s Annalen, Mai, 1855, the subject has been reinvestigated by M. F. 
Laroque (Annales de Chimie, etc., Mars, 1861). The experiments of this latter 
observer appear to confirm fully the results of M. Magnus. According to 
M. Laroque, the rotatory motion arises from accidental causes, is irregular in 
its direction, and is thus in no way dependent on the rotation of the earth 
MINERALOGICAL NOTICES. 
Quartz in Meteoric Iron:—G. Rose (Ber. d. Akad. d. Wissensch, zu Berlin, 
1861, p. 406), has announced the discovery of a minute but perfectly distinct 
erystal of quartz in the Meteoric iron of Xiquipilco in Mexico. This iron is 
nickeliferous, and is mixed with Shreibersite and with particles of a simple 
sulphide of iron. In the valley of Toluca, in which Xiquipilco lies, fragments 
of meteoric iron are scattered over a very considerable area. Hight specimens 
‘from this locality, belonging to the Royal Mineralogical Museum of Berlin, were 
examined in the hope of finding some additional crystals or grains of quartz 
but without success. Prof. Rose suggests, however, that particles of quartz may 
occur amongst the insoluble matters of other iron-meteorites. 
Artificial Formation of Crystallized Specular Iron, Magnelic Iron Ore, 
Magno-ferrite, Periclase, Hausmannite, Cassitirite and Rutile :—These mineral 
species have been obtained by Saint-Ciame Devitte in perfectly-formed crystals 
by the agency of hydrochloric acid gas. By passing a slow current of the gag 
