PEESIDENTIAL ADDRESS. H 



area, and iu admittiug of exactitude iu every respect in carrying out the experi- 

 ments. Waguer also makes use of sheet zinc vessels, with bottoms, of different construc- 

 tion and size, the largest of which are placed upon small railway cars, which, durino- 

 unfavorable weather, can be rolled into glass houses. These vessels are iised in cases 

 where the possibility of loss of nutriment from percolation must be excluded, and the 

 influence of moisture on the experiment controlled. It is to be hoped that Wagner's plan 

 of experimenting may be found successful, for it certainly reduces the cost of experiments 

 to establish the value of manures, and promises to affoid an economical way of ascertain- 

 ing, with some degree of certainty, the quantity and quality of the mauurial substances 

 necessary to raise a soil to the highest degree of fertility. 



G-reat as may be the waste in applying certain fertilisers to crops, and greater as may 

 be the loss from the neglect of barnyard manure, neither of these can compare in extent 

 with the enormous quantities of plant food carried out of towns and cities by their 

 sewers, and which becomes utterly lost to agriculture. Manifold are the schemes and 

 processes which have been set on foot for the utilisation of sewage ; millions of dollars 

 have been wasted in attempting to recover this waste, and still the problem remains un- 

 solved. The probability is that no progress will be made with it until inventors begin to 

 work on the principle which is the foundation of the art of ore-dressing : " Nichts in's 

 Weite gebracht was schon im Engen ist," i.e., " Scatter nothing abroad which is already 

 within narrow limits." Of all the plans which have been tried, the only one by which a 

 slight utilisation of this material has been effected is by irrigation, and even in this case 

 little absorption of manurial constituents by the soil takes place, unless it is comparatively 

 unfertile, and is at the same time occupied by growing plants. It has also been discovered 

 that a large proportion of the nitrogen contained in the sewage water escapes utilisation, 

 even under the most favorable circumstances, and is found in the water of the drains in 

 the form of nitrates. Sewage water, itself, never contains nitrites or nitrates, while in 

 certain English experiments, 14 to 25 per cent, of the nitrogen, present in it as ammonia, 

 was found to have been converted into nitric acid in its passage through the soil. Similarly 

 at the irrigation fields, near Breslau and Berlin, 26.6 per cent, and 28.2 per cent, respectively 

 of the total nitrogen contained in the sewage was found to have been oxidised and carried 

 into the drains. 



While there is only too much reason for deploring the enormous waste which all 

 civilised countries sustain iu the sewage of their cities, and too much reason to fear that 

 diseases are disseminated by its means, it is somewhat comforting to find that this material 

 does not contaminate rivers to the extent that is generally supposed. Beneficent nature 

 interferes, and counteracts the consequences of man's folly, in a manner that ought to 

 awaken his gratitude. It appears that rivers possess an extraordinary power, as they roll 

 on, of absorbing oxygen from the atmosphere, and making use of it to free themselves 

 from the impurities they receive from cities. According to Hulva, who examined the 

 waters of the River Oder, taken from above the city of Breslau, then at the point where 

 the sewers of that city discharge themselves, next immediately below the city, and lastly 

 at Moselwitz, nine kilometres further down, it appears that at the latter point, the water 

 possesses nearly the same composition that it does above the city, while at the inter- 

 mediate places it contains from four to twenty-fiA'^e times its normal quantity of ordinary 

 and albumenoid ammonia. Such investigations would not be out of place at many points 



