150 Composition of Waters of Land-Drainaije and of Rain. 



strated the truth of the supposition or shown its fallacy. There 

 can, however, be no harm in urging, as I have often before clone, 

 the more extensive adoption of every method which will bring 

 manures into perfect contact with the soil. Foremost in this rank, 

 of course, stands the judicious use of manure in the liquid state ; 

 in the absence of this, the next best means of bringing about this 

 combination between the soil and manures, is the method of 

 compost heaps, and it seems to me that advantage might be taken 

 of this plan to a much greater extent than is at all usual. Even 

 in the use of artificial manures, such as guano and superphos- 

 phate, I think it would greatly increase the efficacy of their appli- 

 cation, if for some time before they were employed they were 

 mixed with a considerable portion of good soil and moistened. 

 In fact I would make a compost heap of guano as is ordinarily 

 done with farm-yard manure. Such an idea may, I have no 

 doubt, find plenty of objections on the score of difficulty, expense, 

 and what not. All the chemist can do is to point out princij)les — 

 if they are inadmissible in practice from some causes of which he 

 is unaware, that is a sufficient reason for not putting them into 

 practice; but if on the other hand his suggestions are not alto- 

 gether impracticable, sooner or later some intelligent enterprizing 

 farmer will find the means of bringing them to bear. 



On the present, as on former occasions, my axiom is, that the 

 more perfect the contact of every particle of the manure with the 

 soil the better will be its effect upon vegetation. How that per- 

 fect contact is to be accomplished it is for the practical farmer to 

 realize. 



Before concluding this paper it may be of advantage to re- 

 capitulate the principal points to which we have been led by the 

 present inquiry. We find then, that through every acre of land, 

 whether naturally or artificially drained, thei'e passes annually a 

 quantity of water ecjual to 42 '4 per cent, of the rain-fall, and that 

 where this latter is 25 inches the quantity of drainage-water is 

 equal to about 240,000 gallcms in that space of time. That even 

 where the land is very highly manured this large quantity of 

 water removes from the soil only inconsiderable quantities of the 

 most important mineral ingredients of soils, namely, potash and 

 jihosphoric acid. That the quantity of ammonia carried off from 

 land by the drainage-water is also inconsiderable, but that nitrogen 

 in the form of nitric acid is, especially in highly manured land, 

 to be found in very large quantity in the water of land-drainage. 

 That the quantity of nitrogen in the form of ammonia and nitric 

 acid in rain-water is very much smaller than has been supposed, 

 and quite inadequate, of itself, to account for the natural fertility 

 that has been ascribed to it ; and that it is to these substance?, as 

 existing at all times in the air, and absorbed from it by the soil 



