49 



in 1881, in an 8-inch "Board of Trade" gauge as well. 

 At different periods, the nitrogen as ammonia and as 

 nitric acid has been determined in the rain waters. 

 The chlorine and sulphuric acid have also frequently 

 been determined, and sometimes the organic nitrogen. 



Three " Drain-gauges," each of one-thousandth of an 

 acre area, have been constructed for the determination 

 of the quantity, and the composition, of the water pass- 

 ing, respectively, through 20, 40, and 60 inches depth 

 of soil, with the subsoil in its natural state of consolida- 

 tion. These "drain-gauges" have been in operation 

 from September 1870 up to the present time ; the soil 

 having been unmanured and uncropped since 1868. In 

 the early years these drainage-waters were only occa- 

 sionally analysed, the constituents determined being the' 

 nitrogen as nitric acid, sometimes that as ammonia and 

 as organic nitrogen, and the chlorine; but from May 

 1877 up to the present time, the nitrogen as nitric acid, 

 and the chlorine, have been determined in proportionally 

 mixed samples of each month. 



Lastly, each of the differently manured plots of the 

 permanent experimental wheat-field (Broadbalk) has a 

 separate pipe-drain, and in December 1866 most of 

 these, and in November 1878 the remainder, were dis- 

 connected from the main for the purpose of collecting 

 samples of the drainage water from each, for analysis. 

 In the early years samples were not so regularly taken 

 as subsequently, but from April 1878 up to the present 

 time, they have been collected for analysis on almost 

 every occasion of flow. The late Dr. Voelcker analysed 

 65 samples of the drainage-waters collected at different 

 periods, in 1866, 1867, and 1868. He determined in 

 them, not only the amount of nitrogen as nitric acid and as 

 ammonia, but he made complete analyses of the mineral 

 matters they contained. Of the samples collected from 

 1868 to 1873 inclusive, Dr. Frankland made 103 

 analyses, his determinations having reference chiefly to 

 the amount and the condition of combination of the 

 nitrogen, and to the amounts of carbon and of chlorine. 

 From 1876 up to the present time, the nitrogen as nitric 



D 



