134 Composition of Waters of Land- Drainage and of Rain. 



In some instances we find a good deal of chlorine (as common 

 salt). 



Oxide of iron and silica are found in the waters in small propor- 

 tion. They are not of much importance in a practical point of view. 



But if we turn to the only two substances which from their 

 known influence as manure, and their relative deficiency in soils, 

 or cost when added, we should consider of the first importance 

 in this inquiry, namely, phosphoric acid and potash, we are gra- 

 tified to find that they are present in the waters in remarkably small 

 quantity only. In four out of seven cases the potash was so small in 

 quantity that it could not be estimated ; in No. 6, which contains 

 the most, it is only present to the extent of two-tenths of a grain per 

 gallon. The same is true of the phosphoric acid, which, in three 

 instances out of seven, could not be determined on account of its 

 smallness in cjuantity. No. 7, the extreme case, reaches only 

 one-tenth of a grain per gallon. It must not be imagined that 

 by the word trace it is meant to imply that there is no potash or 

 phosphoric acid to be found ; it is merely to be understood that 

 it is so small that there is no possibility of determining it ; and, 

 inasmuch as in the other cases the quantity has been ascertained, 

 it is obvious how small must be that portion with which Ave are 

 unable to deal. 



I propose presently to show what quantities of the different sub- 

 stances named are carried off by the whole drainage of the year, 

 and it will then be seen how practically unimportant is the loss 

 of phosphoric acid and potash from this cause. 



We will now see what are the facts in regard to organic matter, 

 nitric acid, and ammonia. 



The following Table gives the quantity of these substances 

 in the eight samples of water received from Mr. Paine : — 



Table IV. — Organic Matter, Ammonia, and Nitric Acid in Land Drainage 

 Waters, from Mr. Paine. 



(Grains in the imperial gallon.) 



Soluble 

 Organic Matter. 



7*00 

 7-40 

 12-50 

 5-60 

 5 • 70 



5-80 j 



7'40 . ! 



not determined ' 



Nitric Acid. 



14- 



12- 



1" 



74 



•95 



3-45 



8-05 



11-45 



3-91 



0*018 

 0-018 

 0-018 

 0-012 

 0-018 

 0-018 

 0-006 

 0-018 



First, of the " organic matter" contained in drainage-waters, 

 as exhibited by this Table. That it is in some instances very 



