Composition of Waters of Land-Drainage and of Rain. 139 



nesia, soda, or some other base, and we find it in combination 

 with these in the drainage water. 



The production of nitric acid and its removal by drainage 

 water may be considered as a double evil, inasmuch as it neces- 

 sarily carries with it some one or other of the alkaline bodies. 

 In the absence of those more common and to vegetation less im- 

 portant alkalies, lime and soda, this nitric acid would be the 

 means of carrying off from the soil a portion, and perhaps consi- 

 derable portion of its potash or even its ammonia ; but in all 

 probability such a result would be of rare occurrence.* 



T have alluded to the importance of ascertaining by examina- 

 tion made at different seasons to what extent this removal of 

 nitric acid from the soil was constant or at all to be compared 

 with that which a sample taken at any one time might lead us to 

 suppose. We are not altogether without information on this 

 subject. 



Mr. Paine's sample, No. 7, taken on the 27th December, con- 

 tained 11*45 grains of nitric acid in the gallon. On the 4th 

 April of the present year, or rather more than three months after- 

 wards, when the drains, having never ceased, were still running, 

 although of course in diminished quantity, the water was found 

 to contain 7*57 grains of nitric acid in the gallon.f It is evident, 

 therefore, that the quantity of nitric acid removed from the soil 

 by drainage was decreasing. But we have already seen (Table 

 I.) that in the month of April the proportion of water filtrated 

 through the soil begins to diminish, whilst in the next month it 

 is reduced to about 5 per cent, of the whole, and in the next 

 month to somewhat less than 2 per cent. We may fairly conclude, 

 therefore, from the composition of the drainage water at these 

 two periods (the latter end of December and the commencement 



* I cannot help regarding these analyses of drainage-water as a strong con- 

 firmation of the general truth of my previous results with regard to the chemical 

 phenomena of absorption in the soil, not only for ammonia, but in griulatioii for 

 each base iu the soil. In a supplement to his ' Principles of Agriculture,' 

 Professor Liebig takes occasion to review the facts developed by my experiments 

 on the ' absorptive power of soils,' which facts he proposes to show, at once, were 

 well known, and have no f)undatioii in truth. My experiments on double silicates 

 are characterised as "theatre decorations," and such information is called giving 

 "a stone where bread is asked for" by the fanning body, which is, according to 

 Professor Liebig, justified " in taking shelter from such chemical teaching in a 

 wholesome empiricism." 



The translation of these criticisms of Baron Liebig has for months been in cir- 

 culation iu America. I have every liope that when a second edition of the 

 'Principles', is published in Kngland, the Supplement will also appear. Should 

 there be no sign of any such publication, I shall take means to lay tlie whole 

 question before the agricultural public. 



t Since the above was in tyi)e, I have received from Mr. Paine a third sample 

 of this same water. It was collected on the llth June, when the drain was 

 ninniug very slowly, about one <]uart per minute. Upon analysis it was found to 

 contain 7"02 grains of nitric acid per gallon. 



