102 L. COHEN. 



especially on first warming. On dilution with water, 

 gummy masses (cellulose nitrate) separate out, and are an 

 obstacle to proper manipulation. The soil treated in this 

 way required 3 hours to elutriate, the weight of residue 

 being 5*9 grams. The latter in this case was cleaner than 

 that produced by the alkali method, but still contained 

 considerable quantities of clay and organic matter. Thirty 

 grams of the same soil were also treated by heating with 

 dilute hydrochloric acid to boiling in a beaker, powdered 

 potassium chlorate being cautiously added, a little at a 

 time, as the reaction is violent and attended by the escape 

 of large quantities of chlorine. The boiling was continued 

 for half an hour, and on elutriation 4*5 gram of residue 

 remained, possessing the characteristics of that from the 

 previous experiment. The overflow water became quite 

 clear in 1 hour 45 minutes. 



A stiff yellow clay soil from the Dorrigo Scrub, from 

 which by boiling with water it was impossible to obtain 

 reasonable figures for the sand and clay percentages, was 

 treated by boiling 30 grams with 150 cc. of the zinc chloride 

 reagent for half an hour. The elutriation in this case took 

 15 hours, but the residue after this time was a pure, clean, 

 sharp sand, the grains varying considerably in size, entirely 

 free from both clay and fibre, and weighing 2*8 gram, 

 making 9"3°/°. The same soil by the pestling process yielded 

 1*6 gram sand, showing the very considerable loss of sand 

 that occurs in this method. This soil contained a rather 

 large amount of organic matter, viz., 15*66°/°, though from 

 its appearance and physical properties, it could not be 

 classed as a humus soil. 



Most of the soils from the Myall Greek Estate, recently 

 thrown open for settlement, presented much difficulty in 

 the mechanical analysis, and the most unpromising of these, 

 an exceedingly stiff black clay, was selected in order to 



