Composition of Waters of Land-Drainage and of Rain. 149 



one of its principal ingredients is uric acid, a compound contain- 

 ing nitrogen not in the condition of ammonia. It is therefore 

 quite possible that under certain circumstances guano may give 

 rise to the production of nitric acid which the drainage-\vater may 

 carry off; and this observation brings us to the last head of our 

 inquiry, namely — 



What circumstances are likely to increase or diminish the icaste 

 from such causes ? 



In a great degree this question must be left for ulterior exami- 

 nation ; a knowledge of the cause of the production of nitric acid 

 in the soil will naturally lead to a remedy for its prevention, 

 supposing such a remedy exists ; at present, however, as we have 

 just seen, the cause is not so obvious. 



The two points to decide are, Does organic matter containing 

 nitrogen give rise to the production of nitric acid by filtration 

 through the soil? aind, Is ammonia oxidated by such filtration? 

 If these questions are answered in the negative, then I think we 

 shall find a practical solution of the only other difficulty, which 

 is, the oxidation of the manure into nitric acid during its decay. 



It is generally agreed that the first stage in decomposition is 

 the production of ammonia, but that in the absence of any sub- 

 stance to unite with this ammonia, it passes, in the presence of 

 excess of air, at once into nitric acid. We can readily understand 

 then, that a nitrogenous substance undergoing putrefactive 

 fermentation by itself would give rise to nitric acid ; and such 

 would be the case with all manures, such as bones, rags, &c., 

 which by their very nature cannot but lie in masses of more or 

 less size. It may be however, that if these substances could be 

 reduced to a comparatively fine condition and then intimately 

 mixed with the soil, that the production of nitric acid would in 

 great measure be obviated. In this latter case, the soil having 

 the power to unite with ammonia would arrest the action at that 

 point. It may seem possibly in opposition to this view, that 

 manuring with guano should give rise to nitric acid, as it is seen 

 to do in the case of Mr. Wren Hoskyns' samples ; but it may 

 well be doubted whether the mixture of this manure with the 

 soil in the ordinary system of broad-casting is by any means so 

 perfect as is desirable, and in all probability the cause is the 

 same in both cases.* As I said before it is better to leave this 

 matter open at present until further experiments have demon- 



* This is one of the grounds on which I am led to the practice of mixing the 

 guano with an efiual hulk of salt, in the hopper, at the time of sowing it, after the 

 seed-drill. It certainly lulps the act of fliitribution greafly, especially if, accord- 

 ing to my practice, the guano be " pounded " very fine beforehand ; and the rapid 

 assumption of moisture by salt nmst, I conceive, favour its more minute dis- 

 semination in tile soil.— (J. W. II. 



