302 REVIEWS 



ates, iron oxide as hematite, and instead of ferrous iron was used either 

 ■siderite (FeC0 3 ) or a fayalite-slag (Fe 2 Si0 4 ). 



The pulverized substances were intimately mingled and at first 

 carefully heated to drive off the water. For the larger and coarser 

 experiments common commercial mixtures were used, but in all cases 

 the proportions were calculated as nearly as possible with reference to 

 the known composition of igneous rocks. For a special group of exper- 

 iments, combinations of minerals in theoretical proportion were pre- 

 pared, in order to test the theory of solutions; the rock-forming sili- 

 cates are conceived as capable of supersaturation of a magma, and, in 

 proportion to their relative amounts and the nature of the solvent, crys- 

 tallize out in the order of saturation ; all the mineral products were 

 •carefully analyzed and the results were checked in each case by care- 

 fully sampled quantitative analysis of the mixture after fusion, in order 

 that the effect of the addition of new silica or alumina from the cruci- 

 ble walls, by corrosion, might be allowed for. Finally, a special group 

 ■of experiments involved the melting up of pieces of natural rocks, 

 granite, andesite, basalt and others, and these experiments the author 

 is still carrying on. 



The following list will show the great variety of minerals produced 

 by so-called "dry fusion" from silicate magmas : 



i. Oxides: Corundum, Hematite, Ilmenite, Quartz, Tridymite, 

 and a peculiar prismatic variety of Si0 2 . 



2. Aluminates and Ferrates : Spinel, Chlorospinel, Pleonast, 

 Hercynite, Magnoferrite, Magnetite. 



3. Silicates : Sillimanite, Cordierite, Olivine, Forsterite, Fayalite, 

 Monticellite, Enstatite, Hypersthene, Augite, Alkaline Augite, Pleo- 

 ■chroic green Augite, Diopside, Wollastonite, Biotite, Lepidomelane, 

 Sanidine, Labradorite, Anorthite, Melilite, Nepheline, Haiiyne, Nosean, 

 Sodalite, and Lagoriolite. 



The following volcanic rocks were artificially produced : Rhyolite, 

 with flow structures, spherulitic basalt-obsidian ; enstatite-basalt with 

 both intersertal-glassy and micro-porphyritic structures; normal basalt 

 with micro-porphyritic structure ; augitite with hyalopilitic ground- 

 mass ; melilite-basalt in both micro-porphyritic and granular forms ; and 

 haiiyne rocks of intersertal-glassy and granular structures. From mix- 

 tures supersaturated with alumina were produced mineral aggregates 

 bearing abundantly crystalline A1 2 3 in the form of corundum and 

 related minerals. Among these were a cordierite-andesite of glassy or 



