E. J. Russell and E. H. Richards 543 



probably faulty by reason of the crudeness of the analytical methods, 

 but Lawes, Gilbert and Pugh^ showed that the losses of nitrogen un- 

 doubtedly took place sometimes, though not always, when nitrogenous 

 organic matter, — wheat-meal, barley-meal, or bone-meal, — was made 

 into an "agglutinated condition" with water, and allowed to decompose 

 in presence of air. Practically no ammonia could be detected. Lawes 

 and Gilbert suggested three possible reactions : 



1. An oxidation analogous to that of the action of chlorine on 

 ammonia, by which free nitrogen is evolved. 



2. A reduction similar to that of a great number of substances 

 upon the oxygen compounds of nitrogen, by which the oxygen is appro- 

 priated and the nitrogen set free. 



3. These two actions may operate in succession the one to the other. 



Little attention was paid to these results at the time. Later on, 

 however, losses of nitrogen were found to occur in the purification of 

 water and of sewage. Angus Smith^ in 1863 observed an evolution 

 of gaseous nitrogen from a dilute solution of putrefying blood, and 

 showed that nitrates gave off nitrogen under certain circumstances. 

 The earlier sewage workers, Frankland^ and others, did not actually 

 mention any loss of nitrogen during sewage purification though the 

 published results show that loss took place. Later sewage workers 

 recognised the loss, and Letts^, indeed, made measurements of the evolved 

 nitrogen, special gasimetric methods being devised for the purpose. 



A serious attempt to grapple with the problem was made in 1896 

 and 1897 at some of the German Experiment Stations, notably Jena, 

 in consequence of the request made by the German Agricultural Society 

 for an investigation into the losses of nitrogen from farmyard manure. 

 These losses were well known to occur, and there was reason to suppose 

 (see p. 504) that they did not arise wholly from volatilisation of ammonia. 

 The first hypothesis, set up by Wagner, was a reduction hypothesis to 

 the effect that nitrates are present in the manure, and these decompose 

 in absence of air giving rise to nitrogen, the change being the one that 



1 Lawes, Gilbert and Pugh, Phil. Trans. 1861, 431-577, "On the sources of the 

 nitrogen of vegetation." 



^ Angus Smith, Memoirs Manchester Lit. and Phil. Soc. 1865, vol. xxn. (vol. ii. of 

 3rd Series), 47-63; 1867, vol. xxiv. (vol. iv. of 3rd Series), p. 37; also Report to the Local 

 Govt. Board, 1882. 



* Frankland, Denison and Chalmers Morton, Royal Commission, Pollution of Rivers, 

 1868, vols. I.— IV. 



* Loc. cit. (see p. 527 above). 



