138 On the Composition of Waters of Land-Drainage. 



5. A glance at the combined results of the several analyses 

 shows that much of the lime in the drainage passes away in the 

 form of nitrate of lime. 



6. All the drainage-waters from the plots to which chlorides 

 had been applied contained considerably more chlorine in the 

 form of chlorides than the drainage from plots upon which no 

 chlorides had been used. 



Thus the drainage from unmanured Plots 3 and 4 contained 

 in round numbers 1 grain of chlorine, and that from Plot 5, not 

 dressed with manures containing chlorides, yielded about the same 

 quantity of chlorine, whilst the drainage from Plot 6, to which a 

 mixture of 200 lbs. of sulphate and chloride of ammonia in equal 

 proportions had been applied, contained 1*69 grains of chlorine ; 

 that of Plot 7, dressed with 400 lbs. of mixed ammonia-salts, 

 gave 2 '54 grains of chlorine ; and that of Plot 8, manured with 

 600 lbs. of mixed ammonia salts, yielded 3*59 grains of chlorine. 



7. The same remark applies to sulphuric acid. The plots 

 manured with sulphates yielded drainage richer in sulphates 

 than those to which no sulphuric acid, in the shape of readily 

 soluble sulphates, had been applied. 



Professor Way has shown that soils have not the power of 

 absorbing and retaining the acid elements of chlorides and sul- 

 phates, and these results fully confirm his observations. 



8. It is remarkable that the quantity of soluble silica in the 

 drainage from Plot 2, continuously manured with farmjard- 

 manure, contains nearly A:\ grains of soluble silica, which 

 evidently is derived from the rotten straw in the dung, it being 

 well known that straw abounds in silica. 



9. Special attention is directed to the exceedingly small 

 quantities of ammonia which were found in all the thirteen 

 samples of waters. 



Although some of the plots had been annually manured with 

 large quantities of ammonia salts, and Plot 2 with farmyard- 

 manure — containing nitrogen both in the form of ammoniacal 

 salts and of decomposing nitrogenous organic matter, which readily 

 gives rise to the formation of ammonia — all the drainage-waters 

 contained, practically speaking, mere traces of ammonia. The 

 drainage from the highly-manured plots, it will be seen, hardly 

 contained more ammonia than that from the unmanured portions 

 of the same field. 



Professor Way has determined the amount of ammonia in 

 rain-water in a series of samples, supplied to him by Mr. Lawes, 

 representing the whole rainfall at Rothamsted of each month 

 in the year 1855. The following table shows the amount in 

 grains of ammonia and of nitric acid in an imperial gallon of 

 the rain of different months : 



