238 Animal Report on Adulterations, Sfc. 
There is a good deal of difference in the composition of Nile- 
water taken at the beginning and at the height of the flood. In 
the latter stage the suspended matter is nearly four times as large 
as at the beginning of the rise. On the other hand, the amount 
of soluble matter is a good deal less. The decrease of soluble 
organic matter in the second specimen is very remarkable, and 
as there is much more nitrate of potash in the water at the height 
of the flood, it would appear that the nitrogenous organic matter 
is rapidly converted into nitric acid, which, uniting with potash, 
forms nitrate of potash, a constituent which has been discovered 
before in Nile-water, but, as far as I know, not quantitively 
determined. 
Although the soluble saline constituents which are present in 
this and other waters used for irrigation contribute to their fer- 
tilizing properties, in the case of Nile-water it is chiefly the 
suspended matter which produces the well-known and astonishing 
effects upon vegetation. In this suspended matter we have both 
mineral and organic matters in a highly divided and most 
effective condition. If it be remembered that the second speci- 
men of water contained a quantity of suspended organic matter, 
which on decomposition furnishes 3-10ths per cent, of ammonia 
in round numbers, and that, consequently, every 1000 gallons, in 
addition to an enormous quantity of mineral food for plants, 
contain an amount of organic matter in suspension which, when 
deposited on the land, will gradually generate no less than 300 lbs. 
of ammonia, no surprise will be felt at the results practically 
obtained in the irrigated districts of Egypt. 
My object in relating some of the details which were brought 
to light in the course of my examination of Nile-water, is to 
direct the attention of the English farmers to the benefits which 
are in most cases likely to result from a good system of irriga- 
tion. It is well known that some waters are better adapted for 
irrigating purposes than others ; but our information on the par- 
ticular circumstances which determine their relative value is 
very limited. This subject is well worth a careful and extended 
chemical investigation. 
5. For some time past my attention has been directed to an 
examination into the causes of that barrenness which characterizes 
some soils, and the great fertility which distinguishes others. 
Several soils have lately been examined by me, which were 
almost completely barren, and yet neither in their texture nor any 
other physical characteristic presented any indication that marked 
them as such. 
Some important results have been obtained already, and others 
may perhaps follow on further pursuing this inquiry. 
