110 
It will be remembered that in his latest Rivers Pollution 
Report, Dr. Smith gave a series of results showing the com- 
parative purity of different waters according to this method. 
Dr. Leone goes on to say: Since the majority of such 
experimentalists have not taken account in such researches 
of the time which has elapsed from the moment in which 
the water was obtained to that when it was experimented 
upon, and since these experimentalists have ascribed to a 
water thousands and thousands of microbia per c.c. — a water 
which may have required two or three days’ journey from 
its source to the point where it comes to be examined — 
it is to be supposed that these experimentalists have dis- 
regarded the possibility that the purest drinking water may 
be a good medium for the culture of microbia.” 
As regards the latter part of this passage, I wish to point 
out that Dr. Smith specially called attention to the fact that 
very pure spring water contains active microbia. Dr. Smith 
found that all waters gave off hydrogen when sugar was added, 
except distilled water and water which has been boiled, 
which do not give off hydrogen under the conditions speci- 
fied. Dr. Smith found further that, taking a series of sam- 
ples ranging from the very pure spring water of the uplands 
down to the most foul sewage, the quantity of hydrogen 
given off with sugar was apparently proportionate to the 
degree of contamination; and he added that, so far as he 
was aware, there was no water which had not previously 
been boiled or distilled, which did not give evidence of the 
presence of micro-organisms in this way. Dr. Smith showed 
me the proofs of his report containing these statements at 
the beginning of 1884; and from numerous conversations 
with him, I am able to say that there is no room for doubt 
that he was very strongly impressed with the fact that spring 
waters, which may be regarded as pure, offer a medium for 
the culture of microbia. 
I have looked carefuUy through his report, however, in 
