March 8, 1907] 



SCIENCE 



389 



cost of the recovery depends on the costs of 

 transportation, excavation and handling the 

 raw sand. The total cost vpill probably av- 

 erage at least fifteen cents per ton of sand. 



A rising vote of thanks was accorded to the 

 speaker, and the meeting adjourned. 



Frank H. Thorp, 



Secretary 



THE ST. LOUIS CHEMICAL SOCIETY 



At the regular meeting of the society on 

 February 11, Mr. R. S. Sherwin presented a 

 paper entitled ' The Analysis of Fluorides, 

 especially in regard to Calcium Fluoride.' 

 The speaker dwelt chiefly on the difiiculties 

 connected with the determination of the flu- 

 orine, and the methods of overcoming the 

 difficulties under various conditions. Mr. E. 

 J. Ericson opened the discussion. He dealt 

 chiefly with the determination of silica con- 

 tained in fluorides. 0. J. Borgmeyer, 



Corresponding Secretary 



THE GEOLOGIICAL SOCIETY OF WASHINGTON 



At the 186th meeting of the society, on 

 January 23, Mr. M. E. Campbell described 

 informally some peculiar fine striations, re- 

 sembling glacial striae, on one of the bedding 

 planes in the Portage flags in a quarry at 

 Watkins, New York. The stria are almost 

 exactly parallel and absolutely straight for 

 ten or fifteen feet, as exposed in the quarry. 

 The surface of the rock shows the develop- 

 ment of slaty cleavage normal to the direction 

 of the strise. The appearance of the striations 

 indicates that they are the result of movement, 

 either of a glacier or of the overlying rock 

 mass. In the vicinity of Watkins the hills 

 rise 300 or 400 feet high, and consequently 

 this particular bed of rock is overlain by an 

 average thickness of 200 or 300 feet of strata. 

 The objection to the hypothesis of rock raove- 

 ment is that in places there are cross strise at 

 an angle of 20° or more from the principal 

 lines. Seemingly this could not have been 

 produced by movement in the rock mass, and 

 the only other explanation that seems to apply 

 is glacial movement, which, if true, would 

 mean that a glacier invaded this region in 



late Devonian time. This hardly seems pos- 

 sible, and specimens of the striated rock were 

 exhibited in the hope that suggestions would 

 be offered regarding their mode of origin. 



Mr. Fred E. Wright exhibited an interesting 

 aggregate of artificial copper and silver crys- 

 tals prepared in the geophysical laboratory 

 and formed in the upper part of a steel bomb 

 lined with a silver-plated copper tube. Into 

 the bomb 25 c.c. of water, 1 gr. ammonium 

 chloride and 1 gram of tremolite had been 

 introduced and the whole heated in an electric 

 resistance furnace at 500° 0. (465-540) for 

 three and one half days — the water being above 

 the critical temperature and under a pressure 

 of considerably over 200 atmospheres. The 

 solution attacked the silver-copper tube near 

 its base and redeposited the copper and silver 

 in separate crystals in the upper and cooler 

 part of the tube. In the lower, hotter part 

 of the tube, particles of copper silver alloy 

 and not separate crystals were observed. The 

 inference was dravTn that the aggregates of 

 native copper and silver of the Lake Superior 

 region, which are not alloyed, were formed at 

 temperatures below 400° ; a well-established 

 fact deduced from abundant geologic evidence. 



Regular Program 

 Artificial Magnesian-Pyroxenes and Amphih- 



oles: Mr. Fred E. Wright. 



The results of an extended series of experi- 

 ments on these minerals performed by Messrs. 

 E. T. Allen, J. K. Clement and the speaker, 

 in the geophysical laboratory of the Carnegie 

 Institution of Washington, were described 

 briefly, and obvious geologic conclusions de- 

 duced therefrom. Four forms of magnesium- 

 metasilicate were prepared artificially, and 

 found to correspond respectively to monoclinic 

 pyroxene, to enstatite and to monoclinic and 

 orthorhombic magnesian amphiboles. The 

 monoclinic pyroxene was formed in a number 

 of ways, and although it closely resembles 

 other pyroxenes, both optically and crystallo- 

 graphically, it is easily recognized in the thin 

 section by its polysynthetic twinning after 

 the orthopinacoid and by the normal sym- 

 metric position of its plane of optic axes. 

 Measurable crystals of the other forms were 



