156 Inorganic Matter lost in Drainage Water. [Sept., 



enabled to collect a third sample (of course from the same drains), 

 and having submitted them to analysis, the following are the re- 

 sults: 



Second Sample. — 18 lbs. of drainage-water on evaporation 

 gave 15-2 grs. of solid residue, or about -844 grs. to the lb. 



Oro;anic matter and water in combination, 3'4 



Sibca, 0-9 



Silicate of alumina, .... 0'4 



Chloride of magnesium, - - - 1-12 



Chloride of sodium, - - - - 18 



Chloride of calcium, ... - 3-0 



Sulphate of alumina, ... Q-Q5 



Peroxide of iron, - - - - 2' 1 



Phosphate of lime, .... 0-3 



13-87 



Third Sample. — 18 lbs. of drainage-water on evaporation gave 

 27-5 grs. of solid residue, or about 1-525 grs. to the pound. 



Organic matter, &c., ... 7'8 



Silica, 0-7 



Silicate of alumina, . _ - - 0-2 



Peroxide of iron, .... 2-25 



Phosphate of mag-nesia, ... 1-8 



Magnesia, 1-69 



Chloride of sodium, - - - - 2-615 



Chloride of calcium, - - ^ - - 2-107 



Carbonate of lime, .... 0-7 



Phosphate of lime, - - - - 3-1 



Phosphate of alumina, ... 0'45 



25-412 



I should here observe that the first sample, collected in No- 

 vember, after the drains had been dry for many weeks previous, 

 contained 2-25 grs. of solid residue to the pound; whereas that 

 collected in the following April, (No. 2,) after the land had been 

 continually drenched by the winter rains, only gave -844 grs. to 

 the pound. On adding a quantity of easily soluble manure 

 (gunao) to the soil, the first waters (No. 3) that passed through 

 not only brought with them an increased quantity (1-525 grs. to 

 the pound), but they contained many of the very ingredients that 

 constituted the value of the manure itself. At the time the pa- 

 per referred to was read at the Royal Society, Edinburgh, it was 

 suggested that possibly the turbid portion first discharged from 

 the drains after heavy rains might contain matter also very valua- 

 ble to the soil; but on comparing the subjoined analysis with that 



