MICROSCOPICAL EXAMINATION OE WATER. 585 
Mr. Heisch deserves great credit for initiating such an im- 
portant line of investigation, and the combined researches of 
microscopists on the subject may ultimately lead to important 
practical results with respect to the laws of health, by de- 
termining the exact conditions under which the germs of 
various organisms are developed. 
Shortly after the subject was brought before the Chemical 
Society, I had occasion to assist at the examination of a sample 
of water obtained from a well in the neighbourhood of Drury 
Lane, and suspected to contain impurities. To a portion of 
the water Mr. Lewin added a small quantity of pure cane- 
sugar, and in less than twenty hours the mixture became 
turbid, and the liquid when submitted to a microscopical ex- 
amination was found to be literally alive with minute bacterian- 
like bodies in an extremely active condition ; and it was 
obvious that these little organisms by their action on the cane- 
sugar were the immediate cause of the turbidity. The water 
was bright, and there was certainly nothing in its appearance 
to cause any suspicion that it was contaminated with sewage. 
Subsequently it was ascertained that the drain-pipes of an 
urinal not far from the well were stopped up, and that the 
earth around the well was saturated with urine. On being 
informed of this fact, and recollecting that the characteristic 
fungus mycelium had not been observed when the w r ater was 
submitted to the sugar test, I made various experiments 'with 
mixtures of urine, in different stages of decomposition, and 
New River water, and in every instance failed to discover any 
distinctive fungus mycelium, the field being almost exclusively 
occupied by bacterian bodies. 
About six w T eeks after this I accidentally made the observa- 
tion that water which had been passed through animal 
charcoal became turbid when submitted to the sugar test, and 
that a large development of bacterian bodies was produced. I 
had purchased a new charcoal filter in the month of September 
last, and I was naturally led to try the water by the sugar 
test before and after filtration, when to my surprise I found 
that the filtered water became turbid, while that which had 
not been filtered remained bright. This result at first puzzled 
me, but as I had observed last summer, during the course of 
my experiments on fungi, that phosphate of lime exercised 
powerful deteriorating properties by promoting the develop- 
ment of organisms, I was led to attribute the presence of the 
bacteria in the water after filtration to the action in some way 
of the phosphate of lime in the animal charcoal. The mystery 
of this action of the animal charcoal has since been explained, 
as it is known to be a fact that a portion of the phosphate of 
