30 



Numbers i and 2 in the above table give a very fair idea when 

 contrasted with numbers 5 and 6, of the differences which exist between 

 shallow and deep wells. The solids in the latter are much higher, and 

 although chlorides are present even in large amount, they need not 

 indicate sewage contamination, since their presence may be due to 

 chlorides in the soil or in rock strata through which the water has passed. 

 Albuminoid nitrogen should be low in these deep waters; that it happens 

 to be still lower in amount in the shallow wells quoted indicates their 

 freedom from sewage. Number 3 shews sewage contamination not 

 only in its albuminoid nitrogen but in its traces of phosphates, and this 

 is corroborated by its chlorine, for while 66 parts chlorine does not 

 indicate anything wrong in No. 2, one-seventh part as much chlorine is 

 a bad indication in No. 3, since its sewage origin is borne out by other 

 features of the analysis. The free ammonia in No. 4 serves to indicate 

 sewage, and the nitrates here shew past sewage contamination. Num- 

 bers 7 and 8, although deep wells, shew in many items of the analysis 

 that sewage has found entrance to them, and they cannot be safe or 

 desirable sources of domestic supply. 



I had intended interpreting for you the results of analysis ot Ottawa 

 river water for some years past, so far as I have been able to collect 

 statistics ; but this would require at least another half hour, and it is now 

 j3ast ten o'clock. I must therefore defer this portion of the subject 

 until some future opportunity. There remains also the important 

 question of how, by artificial means, the quality of a natural water sup- 

 ply may be improved. This is in itself a subject large enough to 

 occupy a whole evening in its treatment, and must therefore be left to 

 be dealt with in the future. 



-:o:- 





