286 



work sketched above. An outline of the synthetic work 

 on systems of the mineral oxides and a paragraph on the 

 volcano researches will perhaps suffice to indicate the 

 general plan and purpose of the laboratory's work. It 

 should be added that the results of many of the researches 

 of the laboratory, detailed below, have been published in 

 the pages of the Journal (see 21, 89, 1906, and later 

 volumes). 



Mineral Researches. The mineral studies include : 



I. One-component systems: silica, with its numerous 

 polymorphic forms and their relations to temperature 

 and the conditions of rock formation; alumina; mag- 

 nesia ; and lime. 



II. Two-component systems: silica-alumina, includ- 

 ing sillimanite and related minerals; silica-magnesia, 

 including the tetramorphic metasilicate MgSi0 3 ; silica- 

 lime, including wollastonite ; the alkali silicates, par- 

 ticularly with reference to their equilibria with carbon 

 dioxide and with water ; ferric oxide-lime ; alumina-lime ; 

 alumina-magnesia, including spinel; and hematite-mag- 

 netite, a solid-solution series of an unusual type. 



III. Three-component systems: silica-alumina-mag- 

 nesia, completed but not yet published; silica-alumina- 

 lime, complete, including the compounds that enter into 

 the composition of portland cement; silica-magnesia- 

 lime, completed but not yet published, including, however, 

 published work on the diopside-forsterite-silica system, 

 and on the CaSi0 3 -MgSi0 3 series; and alumina-mag- 

 nesia-lime. 



IV. Four components: Si0 2 -Al 2 3 -MgO-Cap : the in- 

 complete system anorthite-f orsterite-silica ; Si0 2 -Al 2 3 - 

 CaO-Na 2 0: the series of lime-soda feldspars (albite- 

 anorthite), and the series nephelite (carnegieite)-anor- 

 thite; Si0 2 -Al 2 3 -Na 2 0-K 2 0: the sodium-potassium 

 nephelites. 



V. Five components: Si0 2 -Al 2 3 -MgO-CaO-Na 2 0: 

 the ternary system diopside-anorthite-albite (haplo-basal- 

 tic and haplo-dioritic magmas). 



Fairly complete studies have also been made of the 

 mineral sulphides of iron, copper, zinc, cadmium, and 

 mercury, and the conditions controlling the secondary 

 enrichment of copper sulphide ores are now being inves- 



