42 



The general scheme for the determination of the other inory^anic 

 constituents is l)riefly outHned in the following^ sentences: One crram 

 of dry soil was weiohed into a 25 cc. platinum crucihle and ignited in 

 the nuififle at a dull red heat for a sufficient leng-th of time to destroy all 

 organic matter, when it \vas remoxed, cooled and weighed. The dif- 

 ference between this and the original weisrht gives the %'olatile matter. 



The ignited soil was then fused with five grams of sodium carbon- 

 ate and the melt digested some time with hot water, acidified with 

 hydrochloric acid and finally evaporated to dryness. This was ex- 

 tracted with warm dilute hydrocloric acid and the residue filtered ofT. 

 dried, ignited and weighed. It was then treated with hydrofluoric acid, 

 evaporated to dryness, ignited and again wei^rhed. the difference be- 

 tween the two weights giving the amount of silica. 



In the filtrate the ses(|uioxi(les of iron, aluminum, phos])horus and 

 titanium were precipitated with ammonia, filtered off, ]:)laced in the 

 same crucil)le with traces of these left from the silica, dried, ignited anrl 

 weighed. The combined oxides were fused with potassium pyrosul- 

 phate, the melt dissolved in water to which a few cubic centimeters of 

 sulphuric acid had been added, filtered, and the residue ignited, wei'^fhed 

 and evaporated with hydrofluoric acid. It was then ignited and arain 

 weighed, the loss in weight representing a last trace of silica included 

 in the comljined oxides, this being added to the amount first obtained. 



In the filtrate from the pyrosulphate fusion the iron was reduced 

 with hydrogen sulphide and titrated with permanganate and the tita- 

 nium determined colorimetricallv in this solution after the faint per- 

 manganate tint had disappeared. The phosphorus was determined in 

 a separate sample as described above. When the amounts of iron, 

 titanium and phosphorus were deducted from the amount of combined 

 oxides the quantity of aliiiiiiiia was obtained. 



In the filtrate from the sesquioxide precipitation, the lime was 

 thrown down with ammonium oxalate and subsequently determined by 

 titration with permanganate. 



The uiagiicsia was precipitated in the filtrate after the removal of 

 the lime and finally weighed as magnesium pyrophosphate. 



The potash and soda were determined bv the Lawrence Smith 

 method (20). 



The anah tical data are the averages of concordant duplicate deter- 

 minations. 



The inorganic constituents in the \arious soil types on the differ- 

 ent drifts are shown in tables 35 to 37. To make evident the variation-^ 

 in individual constituents these are dealt with separately in later tables. 



