4'2 
[North Street.] 
Sulphate of Ammonia ... ... ... .84 
Sulphate of Soda .. ... . 1.13 
Chlorides of Soda and Ammonia .. ... 1.87 
Nitrate of Ammonia,.. ... ... ••• .76 
Free Sulphuric Acid... ... ... ••• 1.96 
Carbonaceous Matter... ... ... ... 1.12 
Greasy Organic Matter ... ... ... 2.63 
Total Grains per Gallon ... 10.31 
[King Square] 
Carbonate of Ammonia ... ... ... .24 
Sulphate of Ammonia ... ... ... -82 
Sulphate of Soda ... ... ... ... 1.23 
Chlorides of Soda and Ammonia ... ... 1.45 
Nitrate of Ammonia... ... ... ... .63 
Carbonaceous Matter . . ... ... .96 
Greasy Organic Matter ... ... ... 1.43 
Total Grains per Gallon ... 6.76 
This apparently small .quantity of only a few grains per gallon of solid 
matter, when multiplied by the total annual fall of rain, becomes extremely 
large. According to the late Mr. Burder the average annual fall of rain in 
Bristol is 30 inches in depth. This would equal 194,451,840 cubic feet, or 
701,360 gallons on every acre. 
If then we suppose the contents to be as in the above analyses, we shall 
have 9 cwt. of solid matter in North Street, and 6 cwt. in King Square per acre, 
annually separated from the atmosphere and carried into our soft- water cisterns 
and drains. 
This is an important fact for an Analyst of the present day, who regards 
the presence of nitrates in spring or well-water as a sign of an impure source, 
and of probable origin from sewage contamination. So that, although a 
chemical analysis may be thoroughly true and correct in all its details, yet 
the evidence deduced therefrom may be, to some degree at least, fallacious. 
It should however be remembered, that rain, collected at the commencement 
of a shower, is always more charged with impurities than at the close. Also 
that the atmosphere is constantly varying in its rate of purity from baromet- 
rical and other obvious causes. 
