No. 2.] EDWARDS WATER ANALYSIS. 89* 



is taken as the standard of absolute purity — not taken for granted 

 but ascertained by experiment. Variations from purity are 

 assessed accordina- to the following plan : 



1. Appearance, blue clear ; pale brown 1 ; pale yellow and 



green 2 ; dark yellow and dark green 4 



2. Suspended matters, traces 1 ; heavy traces 2 ; turbidity 4 



3. For odor, vegetable 1 — 2 ; animal 4 



4. Chlorine -5 gr. per gallon 1 



5. Phosphoric acid, traces 2 ; heavy traces 4 to 8 



6. Nitrogen as Nitrates, &c., -100 gr. per gal. := 



7. Ammonia -005 " = 



8. Albumenoid -001 " = 



9. Oxygen absorbed in 15 minutes. -002 " = 



10. Do. " in 4 hours -010 " = 



11. Hardness before and after boiling 5® = 1 



12. Total solid matter 5 grs. per gal. = 1 



1 3. Heavy metals, traces := 6 



Do. heavy traces = 12 



14. Vegetable debris ^ 4 to 8 



15. Diatoms and Bacteria z= 6 to 12 



16. Hairs and animal debris = 10 to 20 



This scale of valuation allows a considerable latitude for the 

 exercise of judgment on the part of the Analyst and of allowance 

 for exceptional cases. On this scale 10 is assumed to be the 

 maximum for any one of these impurities, and if any single im- 

 purity exceeds 10 the excess is doubled and included in the 

 addition. The classification of waters as more or less pure, after 

 such valuation, is more difficult to agree upon, and will not be 

 accepted without considerable discussion and probably some 

 difierences of opinion. Still the valuation of the results already 

 obtained are of the utmost value, and will be increased by the 

 continued publication of monthly returns to the year's end. 



At present Mr. Wigner recommends the following grouping 

 of waters : 



Waters showing 15 or under are of exceptional purity. 



" above 15 and under 40 1st class. 



" " 40 '- 65 2nd class. 



" '' G5 •' 90 3rd class. 



" " 100. .. . condemned as unfit for use. 



Taking now the results obtained from the analysis of the 

 Ottawa water, I value as follows : 



Vol. X. F 2 No. 2. 



