ANNIVERSARY ADDRESS. 33 



Another standard, suggested by Rideal, is the ratio between 

 the oxidised and the unoxidised nitrogen. In this matter I feel 

 assured that such confusing methods of comparing results will 

 soon be amended and we shall be able to judge an effluent as we 

 now judge a potable water. 



This method of dealing with sewage has been termed a process 

 of biolysis ; it may with reason be called the zymolysis of sewage, 

 since the changes are brought about through the agency of fer- 

 mentation. It is, in reality, the natural method of sewage puri- 

 fication subject to control ; I would emphasise the latter phrase — 

 purification subject to control — because, all the processes hitherto 

 known, have not been kept under control, but have been the ruin 

 both of inventor and capitalist. This method, however, is both 

 rational and natural, and man is but going back to 'Nature his 

 dear old nurse,' who has carried on the process and purified the 

 dejecta of animal life during all these centuries : indeed, were it 

 otherwise, this world must have become but a huge charnel house. 

 As it is, the micro-organisms of purification and nitrification have 

 full action; antiseptics and disinfectants being wholly superfluous 

 in fermenting the mixture of slops, kitchen waste, storm water 

 and dejecta, whereby the solids break up and pass into solution, 

 gases being evolved. The liquid is then allowed to nitrify, with 

 access of atmospheric air resulting in an effluent being produced 

 which may be purified to a degree equal to some drinking waters. 

 The process now being tried at Botany is intermittent, but there 

 is no reason why it should not, when worked properly, become 

 continuous, requiring very little attention. 



Here then is a field eminently suited to the energies and 

 capabilities alike of the chemist and the engineer; here also lies 

 the explanation of the reason why sewage farms were failures and 

 could not be other than failures. Finally we have the end in view 

 with regard to the disposal of city sewage, for if we must have the 

 sewage carried out of our dwellings by the aid of a current of 

 water, and I admit it to be the easiest method for populous 

 centres, although not the easiest in country houses where, I still 



C— May 2, 1900. 



