Foote and Bradley — Solid Solution in Minerals. 345 



The proportion of calcium in this case is much larger than is 

 commonly found in a dolomite, but it cannot be regarded as a 

 limiting ratio, as some of the primary dolomite was present. 



Our results do not show whether the effect of increased tem- 

 perature will be to increase or diminish the proportion of lime 

 at the mixing limit. In this case, as in that of calcite, it is 

 probable that the investigation of limestones containing mag- 

 nesia would give some information. 



In conclusion, we wish to call attention to the fact that the 

 quantitative isomorphous relations between other mineral car- 

 bonates are quite unknown. To what extent, for instance, 

 siderite or rhodochrosite can take up calcium carbonate has 

 not been determined. It seems not unlikely that some of 

 these problems, at least, may be settled by artificial prepara- 

 tions, and this method would have the very great advantage 

 of working under known temperature conditions. 



Chemical and Mineralogical Laboratories 



of the Sheffield Scientific School of Yale University, 

 New Haven, Conn., Feb., 1914. 



SCIENTIFIC INTELLIGENCE. 



I. Chemistry and Physics. 



1 . Fused Magnesium Chloride as a Crystallizing Agent. — K. 

 A. HoFMAisnsr and K. Hoschele have observed that magnesium 

 chloride in the anhydrous, fused condition is an excellent solvent 

 and means of crystallization for many inorganic substances. The 

 salt melts at 708° C, a temperature easily obtained by means of 

 a good Bunsen burner, to a very mobile liquid which dissolves 

 many metallic oxides, and some of these crystallize very well 

 upon cooling the solution. Other oxides, and particularly sul- 

 phates, react with the fused magnesium chloride and yield vola- 

 tile chlorides, as for example the chlorides of beryllium, zinc, 

 iron and tin. In other cases compounds of the spinel class are 

 formed by the combination of oxides with magnesium oxide. The 

 latter is formed by the action of the moisture of the flame or the 

 oxygen of the air upon the magnesium chloride. This action 

 leads also to the formation of large brilliant octahedral crystals 

 of magnesium oxide (periclase) which often become mixed with 

 other products. This decomposition of magnesium chloride leads 

 to the corrosion of platinum, gold, silver and copper vessels in 

 which the fusions are made. The platinum is deposited again in 

 the form of beautiful hexagonal crystals, the gold forms iso- 



