Io BURTON WATERS—DRINKING AND BREWING. 
a water unfit for drinking purposes, I should be introducing 
a subject which has been the source of more controversy 
and discussion in our special science of analytical chemistry 
than almost any other subject. Such questions as, What 
constitutes organic impurity? How can it be detected? 
How removed? When can its removal be considered as 
effectually carried out? are all of the greatest importance, 
and have been answered in very different ways at different 
times, according to the increase of our knowledge of this 
subject. Now it may occur to some of you to ask, why 
should we be so particular about the contamination of 
water by organic matter, considering that we are living 
organisms ourselves, and make our entire meals of organic 
substances? To answer this question I must refer you to 
that marvellous world that the microscope has disclosed to 
us, the well-named world of microbes, with its innumerable 
multitudes of living individuals, now classified into a great 
number of species and varieties, having very widely different 
functions. You have heard how it has been definitely 
proved that some of our most deadly enemies in the shape 
of contagious disease are conveyed by distinct microbes of 
bacteria, and how some of these are more especially to be 
found in water. Also you have heard how extremely 
minute some of these are, one of the most recently 
discovered—the Influenza Microbe—being, so far as I know, 
the smallest of all, each circular cell not much above 
100,000 of an inch diameter. It is these facts that lead us 
to base so much importance upon the presence or absence 
of organic contamination. Fortunately, the presence of 
contamination in water does not necessarily prove that that 
water would do anyone drinking it any injury, but it does 
prove that it might do so, and it is certainly unwise, if not 
absolutely unsafe to drink it. On the other hand, a water 
free from organic contamination is undoubtedly free from 
this objection, and other points being satisfactory, it may 
be considered as a safe supply. 
