Natural History. '^Mineralogy. BTl 
derablesize and quite transparent, but becoming soon opaque on ex- 
posure to the air, when he allowed masses of iifty pounds weight 
of sulphur, melted in a common earthenware pot, to cool slowly. 
The form of these crystals differs from diat of the crystals of 
native sulphur, the latter being combinations of the prismatic 
system, as described by Haliy, while the former affect the he- 
^miprismatic form of oblique-angular foursided prisms of 90° 
32', terminated by oblique planes, which are set on the obtuse 
lateral edges at an angle of 95° 46', ^variously modified by ad- 
ditional planes, and grouped in twin crystals. Crystals having 
4he same forms as those observed in native sulphur were ob- 
tained when sulphur has been dissolved in the carburet, chloru- 
\ret, and phosphuret of sulphur, and the one kind of crystals 
.may be changed into the other, according to the different me- 
thods employed for obtaining them. In these crystallisations 
of sulphur we have a new well authenticated fact, in addition to 
carbonate of lime, biphosphate of soda, and sulplruret of iron, 
that the same chemical substances, at least, in so far as our pre- 
sent knowledge goes, may assume two different and incompati- 
ble forms of crystallisation, or what is the same thing, that two 
-really distinct and well defined species may consist of the same 
-constituent parts. Professor Mitscherlich has obtained large and 
beautiful rhomboidal dodecahedral crystals of phosphorus from 
solutions of this substance in phosphuret of sulphur*.— 
Ae Cliimie et de Physique^ t. xxiv. p. 264. 
23. Greywacke of the Apennines — It would appear from the 
.observations of Dr Bou^ that the rock described by Hausmann, 
in his account of the Apennines in a former number of this Jour- 
nal, is not true greywacke, but marly variegated sandstone. Dr 
Bone found this greywacke of Hausmann, his variegated sand- 
stone, resting upon magnesian limestone (zechstein) in the Alps 
.and the Carpathians. The ter tiary formations of the Apennines,Dr 
Bone informs us, are similar to those in Hungary and Austria. 
24. Secondary Granite. — The discovery of new granite rest- 
ing upon sandstone and secondary limestone, mentioned at p. 403. 
of vpl. viii, of this Journal, appears to be confirmed by some later 
observations of Bertrand Geslin, a pupil of Brongniart. 
25. Humboldfs Geognosy. — A new edition of this work, with nu-^ 
merous additions and many corrections, will soon appear in Faris^ 
