100 L. COHEN. 



recommends boiling the soil with a one to two per cent, 

 solution of caustic alkali. A large quantity of clay as 

 well as fibre is present in the residue remaining in the 

 elutriator after the treatment of soils by the above methods, 

 especially in the case of peaty soils or those containing 

 from about 15°/° and upwards of organic matter. It seemed 

 then that the difficulty would be overcome and the com- 

 plete disintegration of the clay floccules brought about by 

 subjecting the soil to the action of some substance before 

 elutriation, which would dissolve the cellulose of which the 

 fibre mainly consists. 



A solution of zinc chloride in twice its weight of hydro- 

 chloric acid (40°/° HOI) was found to be the most convenient 

 solvent, the ammoniacal cupric hydrate being unsuitable 

 for the purpose. Thirty grams of a peaty soil from Bun- 

 danoon containing 22*27°/° of organic matter, were passed 

 in a dry state through a wire sieve having 50 meshes to 

 the inch. The fine soil was then boiled for half an hour in 

 a beaker witli 200 cc. of the zinc chloride reagent, and 

 after dilution the whole was washed into the elutriating 

 vessel. After five minutes the overflow water became 

 perceptibly clearer, and in three quarters of an hour was 

 perfectly clear. The weight of the residue on drying was 

 1*85 gram, equivalent to 6"17°/° of sand in the soil, the clay 

 percentage being calculated by difference. 



For purposes of comparison, 30 grams of the same soil, 

 after being passed through the sieve, were boiled with water 

 for 45 min. Three hours and a half elapsed before the 

 overflow became quite free from turbidity, and the dried 

 residue was found to weigh 17*1 gram ; in other words, by 

 this treatment the soil is estimated to contain 57°/° of sand. 

 On examination of the two residues, that from the zinc 

 chloride treatment was found to consist of nothing but 

 clean, hard, sharp grains of sand with no perceptible 



