1905.] 



with reference to the Purification of Sewage. 



261 



Tables I— IX. 



In these tables the estimations of "free and saline ammonia : ' are expressed as 

 ammoniacal nitrogen, those of "albuminoid ammonia" as albuminoid nitrogen, those of 

 nitrites as nitrous nitrogen, and those of nitrates as nitric nitrogen, all in parts of nitrogen 

 per 100,000 by weight. 



Nitrites were estimated by the metaphenylenediamine colorimetric method unless 

 otherwise stated, the sum of nitrites and nitrates by the indigo method (Vienna analyses), 

 or by the copper-zinc couple method (Munich analyses). 



Throughout these tables the grades of reactions are represented as follows : reaction 

 absent by 0, a trace, or faint reaction, by/, definite reaction by +, and intense reaction 

 by ++. 



Oxidisability is expressed in parts oxygen absorbed per 100,000 by weight, less that 

 absorbed by any nitrites present. In figures marked with an asterisk the oxidisability 

 was approximately gauged by the difference between the oxygen absorbed iD the cold and 

 on boiling. 



Table Ia. — Vienna Continuous Filters, showing the Progress of Nitrogen 



Oxidation during Maturing. Filters all started on February 20, 1901. 

 Figures in brackets are weeks elapsed since the start. 



Course of oxidation. 



Tall filter. 



Medium filter. 



Short filter. 



Oxidised N. first detected in 



March 18 



March 21 



March 28 



filtrate 



(4w.) 



(4 w.) 



(5w.) 



Nitrites present in quantity, no 



March 28* 



March 28f 



July 1J 



nitrates 



(5 w.) 



(5 w. ) 



(19 w.) 



Nitrates also present in quantity 



May 24 



May 13 







(11 w.) 



(9J w.) 







July 1 



July 1 







(19 w.) 



(19 w.) 





* 10 parts per 100,000 N. as N.j0 3 . t 1"3 parts ditto. 



% 4 "1 parts ditto, nitrates also present in small amount. 



Table Ib. — Munich Experiments. Filters all started April I, 1903. 





Continuous filters. 



Contact filters. 



Course of oxidation. 





























Tall. 



Medium. 



Short, 



Tall. 



Medium. 



Short. 



Oxidised N. first de- 

 tected in filtrate 



May 2 

 (4 w.) 



May 2 

 (4 w.) 



May 2 

 (4 w.) 



May 16 

 (6i w.) 



May 16 



(6i w.) 



May 16 

 (6* w.) 



Nitrites present in 

 quantity, nitrates 

 present 



May 18 

 (7 w.) 



May 23 

 (7i w.) 











Majority of oxidised N. 

 present as nitrates 



May 27 

 (8 w.) 







June 25 

 (12 w.) 



June 25 

 (12 w.) 



June 25 

 (12 w.) 



Nitrates alone present... 



June 8 

 (10 w.) 



June 13 

 (lOi w.) 



June 13 

 (10£ w.) 



July 9 

 (14£ w.) 



July 9 

 (14i w.) 



July 9 

 (14£ *w.) 



