BURTON WATERS—DRINKING AND BREWING. II 
Recent experiments have shewn that micro-organisms 
may occur in water, sufficiently filtered through soil, to 
render it quite free from direct organic contamination, so 
that the oxidized products of decomposed organic matter— 
the nitrites and nitrates before referred to as the results 
of such filtration—are distinct evidence of the contaminated 
condition of the source of supply, or of the condition of the 
strata through which the supply passes, and remembering 
what I said as to the minute size of bacteria, you will not 
be surprised at chemists considering waters so contaminated, 
as distinctly suspicious, and therefore not pure drinking 
waters, more especially as it has been recently proved that 
some of the pathogenic bacteria, above referred to, are not 
removed from water even after filtration has entirely oxidized 
the whole of the organic matter with which they were 
originally associated. 
In considering the suitability of a water for drinking 
purposes, it must be borne in mind that any arbitrary 
standard for its chemical composition beyond certain broad 
limits, is absolutely out of the question, and only a careful 
consideration of all the facts connected with its source or 
origin in relation to its composition, will enable one to give 
an opinion of real value. Of other substances which it is 
necessary to look out for in drinking-waters, there are many, 
and the composition of a water may depend considerably 
upon surrounding circumstances, as well as the nature of 
the strata through which the water passes. You can well 
understand that a chemical, bleaching, paper, or dye 
works near to a stream might very seriously contaminate 
that stream by fouling it with inefficiently filtered bye 
products. Arsenic, lead, and copper, all of which are 
poisonous even in very minute quantities, (the two latter on 
account of their cumulative character,) are also not uncommon 
contaminations in mining districts, or near works where 
fumes of any of these substances get into the air. It will 
