ANALYSES OF SANDS 



{l>) On treatment for three hours with about lOO parts of hot acids, hot water, 

 or cold water per unit of substance the following data were obtained : 



Substance Dissolved. 



Residue. 



One part HCl and three parts HjO. 



Two parts HNOj two parts HjO 



Boiling HjO 



Cold HjO (i5°C.) 



Percent. 

 30 

 2.6 

 05 

 06 



Per cent. 

 97.0 

 97-4 

 99-5 

 99-4 



(c) In a percolation experiment similar to those on Sample I, only 0.4 per 

 cent, of the substance dissolved, 99.6 per cent, remaining as residue. 

 Percentage Composition. — Sand dried at iio°-i20° C. 



Average. 



SiO, 



Al.Os \ 



Fe,03 ; 



Water 



O in silicate, plus traces, Ca, Fl, SO^, etc. 

 Silica and insoluble silicate, not less than. 



Per cent. 



85.9 



81 



0.6 



Per cent. 

 86.1 



8.3 

 0.4 



Per cent. 

 86.0 



8.2 



0.5 



5.3 



95.0 



General Conclusio7is. — This sand consists chiefly of silica and of insoluble 

 silicates of iron and aluminum. The results of the extraction experiments, in 

 which relatively large amounts of acid, alkali, and water affected it very little, 

 show that the sand is one of the most insoluble and resistant varieties, and that 

 it is not rapidly altered by weathering influences. 



COMPARATIVE COMPOSITION, SAMPLES I AND II. 



Direct comparison of the results for composition of the two sands is made in 

 the appended summary of average analytic data for substance dried to constant 

 weight at iio°-i20° C. : 



Sand dried at iio°-i20° C. 



CaO. 

 SO,. 

 SiOj, 

 AI2O. 

 Fe. " 

 H 



I2O3 \ 

 ,0 



O in silicate and traces of other elements (by difference). 



Chief constituents : Calcium sulphate , 



Silica and silicates , 



Sample ] 



Per cent. 



38.5 



55-1 



3-4 



0.5 

 I.I 

 1.4 

 936 

 3-9+ 



Sample II. 



Per cent, 

 trace 

 trace 

 86.0 



8.2 



05 

 5.3 



94.2+ 



Sample I, from Tularosa desert, consists mainly of gypsum. 

 Sample II, from Samalayuca, is almost entirely silicious. 



Respectfully submitted, 



William J. Gies. 



\^est of El Paso, within the valley of the Rio Grande the character- 

 istic vegetation, above the moist bottom, is creosote bush, with some 



