DESERT BOTANICAL LABORATORY 



Percentage Composition. Sand dried at 30°-35°C. and at iio°-i20°C. 



CaO .... 



SO3 



SiOj .... 

 Al,03 ) 

 Fe,03 / • 



H,0 



Traces : 

 Calcium 

 Calcium 



O, CI, Na, PO< (by difference) 



sulphate, CaSO^.aHjO 



sulphate, anhydrous 



Per cent. 



30-4 



44-5 



2.8 



0.4 



IL 



Per cent. 

 31.2 



43-9 

 2.6 



0.4 



20.8 



Average. 



Per cent. 



30.8 



44.2 



2.7 



0.4 



20.8 



95-8 

 750 



Average. 

 Per cent. 



38.5 



55-1 

 3-4 



0.5 

 I.I 

 1.4 



93-6 



It is very evident that the sand readily dissolves in w^ater. Every rain, no 

 doubt, dissolves some of it and the waters in the district from which the sand 

 was obtained must be heavily charged, probably to the saturation point, with 

 gypsum. On the evaporation of such water, in the sand or in pools, calcium 

 sulphate is again rapidly deposited. 



SAMPLE II. LOCALITY : SAMALAYUCA, CHIHUAHUA, MEXICO. 



General Description. — A composite sand, yellowish to light brown in general 

 appearance. No crystals were detectable in it. The grains were of irregular 

 shape, but of fairly uniform size. None were any larger than the small uni- 

 formly sized ones of Sample I. The grains were angular, with the edges showing 

 the effects of erosion. Glassy and brownish grains predominated. Others 

 with the following colors were to be seen : Amethyst, dull white, dirty yellow, 

 purple, black and red. 



All of this sand passed readily through the sieve used on Sample I. No ex- 

 traneous matter was found in It. 



Qualitative Data. — The sand was very resistant to the solvent action of 

 water, alkalies and acids, scarcely anything dissolving in these fluids, hot or 

 cold. The colored grains were somewhat reduced in number after treatment 

 with acid, the solution in hydrochloric acid having a yellowish tinge. The 

 sand fused with sodium carbonate with great difficulty. The fused mass was 

 bluish-gray in color. On ignition the sand lost only a slight amount of water. 

 It became pink and yellowish-red in places but did not fuse, even in platinum 

 over a blowpipe. Carbonic acid gas could not be obtained from it on ignition, 

 so that the sand is obviously entirely free of organic matter. On drying at 

 iio°-i2o° C. no change in appearance occurred. This sample contained also 

 minute amounts of calcium, sodium, fluoride, sulphate, phosphate, titanate. 

 Quantitative Analysis. 



Preliminary Data. 



A. Sand dried in an air bath at 30°-35° C : 



(a) On drying to constant weight in an air bath at 50°-6o° C. the quantityrof 

 water eliminated was o.i i per cent. 



{b) On drying to constant weight in an air bath at iio°-i20° C. the quantity 

 of water eliminated was 0.19 per cent. 



B. Sand dried in an air bath at iio°-i20° C. : 



(«) On ignition in platinum over a blowpipe the quantity of water elimi- 

 nated was 0.5 per cent. 



