in Melbourne. 195 



sent condition of things did not exist, or, existing, was not 

 known. It might possibly be thought advisable to place a 

 limit on the capacity of cess-pits, even for their legitimate 

 purposes, by fixing a relation between the level of the 

 adjacent ground and buildings and that of the contents, and 

 attaching a penalty to the filling of a pit beyond that limit. 

 But my concern with the legi.slative and engineering 

 relations of this difficult subject is limited to investigating 

 and expounding the chemical and physiological conditions 

 which the legislator and engineer must keep in view. 



I have the satisfaction to conclude this portion of my 

 subject by intimating that both flushing and filtration of 

 sewage have now been stopped in every known instance ; 

 and I have the pleasure to know that my conclusions 

 were favourably received by high scientific authorities in 

 England. 



Art. LV. — Air and Water Poisoning in Melbourne. 

 By Sydney Gibbons. 



[Read 13th December, 1869.] 



PART II. 



ON THE POSSIBLE POLLUTION OF THE YAN YEAN RESERVOIR 

 BY THE DRAINAGE OF WHITTLESEA. 



Let me now recur for a few moments to the observations 

 recorded under Case VII., on the Yan Yean water, which 

 for convenience I here repeat : — 



" Case VII. Yan Yean water from service, clean and 

 svjeet. — Very minute bright green deposit on long standing ; 

 the water being then quite bright. A sufficient quantity 

 of the deposit for microscopic examination was obtained 

 by allowing successive portions of the water to subside in 

 a large conical glass. 



" Solid residue (total per gallon) . . 8 '7 3 6 grains. 

 " Organic volatile matter, do. . . . 2'152 ,, 

 " Inorganic do., do 6"584 „ 



" (The separation of the inorganic matters did not con- 

 cern the question then in hand, nor is it connected with the 

 present inquiry.) 



o 2 



