54 GEOLOGY AND MINERALOGY. 



works on palseontology, if he were to write in the margin against each species 

 the rib formula as here shewn. The eye would then be able to take up at a glance 

 the relations, in this respect, of the described species to the one under examiuation 



due reference being made to any difference that may exist between young and 



adult forms. 



AUTIFICIAL FOKMATION OF CRYSTALLIZED MINERALS. 



By the volatilization of metallic fluorides and boracic acid in covered charcoal 

 or clay crucibles, H. Ste. -Clair Deville and H. Caron* have succeeded in forming, 

 without difficulty, a considerable number of crystallized minerals. Amongst 

 those cited, we may mention : the ruby, sapphire, and other varieties of corun- 

 dum ; chrysoberyll, with the radiating strise and other characters of the American 

 specimens; gahnite, in beautiful octahedrons ; staurolite; zircon; magnetite, &e. 

 In reference to the latter (the magnetic iron ore, which was obtained in the form 

 of long needles, made up of regular octahedrons attached to one another), the 

 authors state that the first formed sesqui-oxide of iron was in this case evidently 

 reduced in part by the high temperature, as confirmed by some of their othef 

 experiments. 



HTGROSCOPIO PROPERTY OF THE ZEOLITES. 



Damour (Annales de Chimie et de Physique: aout, 1858) has confirmed his 

 earlier experiments with reference to the property possessed by the various 

 zeolites, to a greater or less extent, of losing a portion of their contained water 

 in a dry atmosphere, and re-absorbing the same under ordinary atmospheric con- 

 ditions. The water is even re-absorbed, after the mineral has been exposed to a 

 slight degree of artificial heat, amounting in some eases to dull redness. 



IRON OXIDES. 



The number of Poggendorff's Annalen for September, 1858, contains a long 

 and very valuable communication, by Rammelsberg, on the composition of 

 Titaniferous Iron Ore, Red Iron Ore, Martite, and Magnetite. The most important 

 fact, perhaps, shewn in this communication, is the presence of an essential per- 

 centage of magnesia in many specimens of these ores, and, more especially, in the 

 octahedral specular-iron of Vesuvius. The following is a condensed translation of 

 the summary given at the close of the Paper : — 



(1) The greater number of Titaniferous Irons contain equal atoms of Titanic 

 Acid and Protoxide of Iron (including MnO and MgO). 



(2) Magnesia is an essential constituent of all Titaniferous Iron Ores. In the 

 crystallized Titaniferous Iron of Layton, U. S., it amounts to 14 per cent. 



(3) According to Mosander's view, Titaniferous Iron Ore consists simply of 

 FeO, TiO^, with isomorphous replacement of titanate of magnesia (Gastein, Lay- 

 ton) ; or, otherwise, of the same, in union with sesqui-Oxide of iron, mostly in 

 simple proportions. 



(4 & 5) The theory of H. Rose, making Titaniferous Iron Ore to consist of the 

 isomorphous sesqui-oxides of iron and titanium, requires the assumption of a 



* Journal fiir Praktische Chemie No. 11, 1858 ; and Comptes Eendus, t. XL VI, p. 764. 



