ANNIVERSAEY ADDRESS. 23 



should the organism in sewage do ? In the light of experiments 

 made during the last few years, this liquid should be resolved into 

 ammonia, carbonate of ammonia, nitrate of ammonia, marsh gas and 

 carbon dioxide, the chief nitrogen and carbon-constituents of the 

 sewage — in other words, a complete breaking down of highly- 

 complex nitrogenous and carbonaceous bodies into harmless 

 innocuous inorganic compounds. 



This breaking down of nitrogenous matter may be best exempli- 

 fied in its very simplest form, namely, in that of the ammoniacal 

 fermentation of urine, the chief constituent of which is urea, a 

 compound that may be resolved into other compounds, the next 

 simplest in order to those resulting from its ultimate decomposition, 

 (hydrolysis of urea, Dumas), for by simple heating with water, or 

 heating in a alkaline solution, the following change takes place : — 



00 | ^ + 0H 2 = C0 2 + 2 NH 3 



By zymolysis, i.e., by the intervention of life-changes, or in other 

 words by simple ammoniacal fermentation (Pasteur, 1860, Van 

 Tieghem, 1864) this self same change is brought about by the 

 microscopic organism Micrococcus urece. 



By simply abandoning urine exposed to the air, this organic 

 change is quickly brought about ; the whole of the urea becoming 

 converted into carbon dioxide and ammonia, which, at common 

 temperatures, would combine as ammonia carbonate, a compound 

 easily resolvable by the nitrifying organisms into ammonia nitrite 

 and finally, into ammonia nitrate. We have here what has been 

 called the 'septic system of sewage disposal,' the analogue, in some 

 respects, of alcoholic fermentation, but instead of ethylic alcohol 

 being the product of the symbiotic change, it is probable that the 

 simpler methylic alcohoPis evolved, which under the circumstances, 



1 Pasteur, Comptes rendus, Vol. i., 1860. Van Tieghem, Comptes 

 rendus, Vol. lviii., 1864. J iksch. Zeitschrift, f. physiologische Chemie, 

 Vol. v., 1881, p. 395. Leube and Grasser, Virchow's Archiv, Vol. c, p. 556. 



2 Mr. Doherty at my request searched Sydney sewage and effluents 

 therefrom for me thy 1 alcohol but hitherto without success. I am afraid 

 that even should it he found the critic may say it had originally come 

 from methylated spirit thrown away with the liquid domestic waste. 



