ON PUEE WATER. 561 
water containing mncli lime^ is very appreciable to tlie touch in 
the process of washing the hands by the aid of soap. 
Organic impurities are of more importance than inorganic, 
as they seem to be sources of much more fatal and dreadful 
forms of disease. It seems to be difficult to convince many 
intelligent people of the danger of drinking water containing 
organic impurities. They refer to the practice of taking- 
organic matter in water in the form of soup and broth, and 
think this is sufficient to refute the evidence that the organic 
matters in water can do any harm. I think the evidence that 
organic matter in water, under certain circumstances, is inju- 
rious and destructive of health is abundant, conclusive, and 
satisfactory. I gave an instance at the beginning of this 
paper; I now give another. In 1849 cholera prevailed in 
the districts supplied by two of the water companies of 
London — the Southwark and Lambeth Water Companies. In 
that year both companies obtained their supply of water from 
the Thames below Teddington Lock, and from parts of the 
river subject to great impurities. In 1853 the Lambeth 
Company had removed its source of supply from the river 
to a point above Teddington Lock. In that year cholera 
prevailed again in the district supplied by both companies. 
It was found that, during four weeks of 1853, there were 
334 deaths ; of these 286 deaths occurred in 40,046 houses 
supplied with water from the Southwark Company, which 
still obtained its supply from the impure source below Ted- 
dington Lock, whilst in 26,107 houses supplied by the 
Lambeth Company, there were only 14 deaths. This case 
was thoroughly investigated at the time by the late Dr. Snow, 
and the correctness of his conclusions was confirmed by the 
Hegistrar- General. In this instance there can be no doubt 
either that the injurious water did directly communicate the 
germs of the disease, or that it predisposed the inhabitants 
of the district who partook of it to the attacks of the poison 
of cholera. 
Now let us see if we can in any manner account for the 
presence of matter in water which can exert such an injurious 
iiffinence on the system. If we take four or five pints of 
water and allow it to stand for a few hours, and then 
decant off the clear part, leaving a small portion behind, 
say from two drachms to an ounce, and then place a drop 
or two of this remaining portion under the microscope, we 
shall find we have a variety of living beings. They are 
chiefly unicellular organisms belonging- to the animal and 
vegetable kingdoms. The number and variety of them will 
give an approximation to the impurity of the water. They are 
of different kinds, and where the filaments of fungi and certain 
