METHOD OF SEPARATING THE CLAY AND SAND IN CLAY SOILS. 103 



test the effect of the zinc chloride reagent. The soil, after 

 pestling for some five hours, had yielded 9*2°/° of sand. Being 

 too stiff to pass through the 50 mesh sieve in a dry state, 

 30 grams were allowed to soak in water for 15 minutes, 

 and being by this time softened, were rubbed through the 

 sieve into a large porcelain basin. After standing for half 

 an hour the supernatant liquid was poured off, and the soil 

 washed by means of 200 cc. of the zinc chloride reagent 

 into a beaker. Forty-five minutes were allowed for boiling 

 and the elutriation took 4 hours. The residue was of a 

 whitish colour, and, observed under the microscope, was 

 seen to consist of both rounded and sharp perfectly clean 

 grains, of varying size, no fibre or clay particles being 

 present, and weighing 8*55 grams. 



The use of a solution of zinc chloride as described above 

 will therefore be seen to be of great service in estimating 

 the sand and clay in all soils with which other methods of 

 treatment, preliminary to elutriation, give unsatisfactory 

 results. Speaking generally, all heavy loams and clay soils 

 as well as those containing more than the average quantity 

 of organic matter, such as humus and peaty soils, may with 

 benefit be treated by boiling with a solution of zinc chloride 

 in twice its weight of hydrochloric acid, previous to elutri- 

 ation in any of the usual apparatus. 



Table showing the percentage of sand obtained on elutriation of four 

 typical soils, after treatment with various reagents. 





Organic 



matter 



per cent. 







Percentage of Sand. 







Soil. 



Boiling 



with 

 ZnCl 2 in 



HCl 



Boiling 



with 

 Water. 



Boiling 



with 

 2°/o Soda 



Boiling 



with 



strong 



HN0 3 



Boiling 



with 



HCl and 



KCIO3 



Pestling. 



Peaty soil from 



Bundanoon 

 Stiff yellow clay 



from Dorrigo 



Scrub 

 Stiff black clay 



from Myall 



Creek 

 Swampy soil 



from near 



Manly 



227 

 157 



8-6 



359 



6-17 

 9<3 



28'5 



7 



57'0 

 342 



48 2 



21-3 

 16-6 



53 



197 



14-0 



7-0 



15-0 



53 



9-2 



