ANALYSES OF SANDS 9 



ignited sand in water gave a solution slightly alkaline in reaction. Only a minute 

 trace of carbonic acid gas could be produced from the sand on ignition, a fact 

 showing that practically no organic matter is contained in it. Such organic 

 matter as was actually present in the few particles separated from the sand con- 

 sists, as already stated, of the fragments of insects, e.\creta of animals, etc., and 

 is too slight in quantity to have much significance as nutrient material for plants. 



On drying a sample of the sand, in an air bath at lOo" C, it soon became 

 translucent and finally snow white. The grains retained their original shape. 

 Water of crystallization was eliminated in abundance. The sand contains traces 

 of sodium phosphate and chloride. The larger particles removed with the sieve 

 contained a more decided quantity of chlorine, 0.7 to 0.9 per cent. 

 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 iio°-i20° C. the quantity 

 of water eliminated was 19.9 per cent. 



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

 the substance remained the same. 



(c) On continuous percolation at room temperature of small quantities of dis- 

 tilled water at a time over the sand, until about 100 parts water to one of sand 

 was used, 79.9 per cent, of the sand was dissolved and only 20.1 per cent, of it 

 remained as residue. The latter was still dissolving when the experiment was 

 discontinued and further percolation would have reduced the amount of residue 

 (see under B., [d) 4 below). 



(d) On continuous percolation, as above, with distilled water at 30° C. the 

 dissolved matter amounted to 87.1 per cent., and the residue to only 12.9 per 

 cent. Further percolation would have decreased the weight of the residue (see 

 under B, {d) 3 below). 



B. Sand dried in an air bath at iio''-i20^ C. 



(a) On ignition in a platinum crucible over a blowpipe the loss of weight was 

 I.I per cent. 



{&) On,treatment for three hours with about i liter of hot acids, hot water or 

 cold water per gram of substance the following data were obtained : 



Substance Dissolved. 



Residue. 



One part HCl and three parts HjO 



Two parts HNO3 ^"^ two parts H,0.. 



Boiling HjO 



Cold HjO (X5°C.) 



Per cent. 

 97.4 

 97.8 

 94-3^ 

 96.4 



Per cent . 

 2.6 

 2.2 



5-7 

 3-6 



Some General Deductions. — The analytic results set forth in the above table 

 and in that on the following page show that the sand is mainly composed of 

 grains of calcium sulphate derived from crystalline gypsum. Silica and also 

 silicate of iron and aluminum are present in small amounts. Insignificant quan- 

 tities of soluble substances such as chloride (probably of calcium) may also 

 be detected. 



The sand is free from nitrogenous matter except such minute "amounts of 

 animal ddbris and excreta as have already been referred to. 



'Calcium sulphate is more soluble in cold than in hot water. 



