and Water used for General Purposes. 
A good idea of the general character of the organic matter in 
water may often be formed by noticing the smell which is 
given off when the residue obtained by evaporating one pint of 
water is heated over a spirit or gas flame in the dish in which 
it was obtained, allowing the air free access. Vegetable or 
peatv matter manifests itself, on heating, by its peculiar smell ; 
and moreover the fumes which are given off, when tested with 
moistened litmus-paper, show a slight acid reaction. Animal 
organic matter, on the other hand, on heating, produces fumes 
which turn reddened litmus-paper blue, and thus have an alka- 
line reaction ; the vapours which are generated when animal 
organic impurities are exposed to a strong heat possess the pecu- 
liar smell, of burned or singed hair or feathers, which characterises 
all nitrogenous organic matters. 
By these simple experiments it may sometimes be decided at 
once, and without much trouble and in a short time, whether a 
water is wholesome, or decidedly injurious to health. Other 
experiments of greater or less value in testing water might be 
mentioned ; but I abstain from doing so, because if the prelimi- 
nary trials which I have recommended fail to give a decided 
answer to the inquiry for which they were instituted, the safest 
plan in that case, for a person who has not had the opportunity of 
making himself acquainted with analytical processes, is to send 
the water, on the qualities of which he desires information, to a 
qualified scientific chemist who has had much experience in the 
examination of potable waters. 
In most instances one gallon will be sufficient for the analysis. 
The water may be transmitted to the laboratory in a clean and 
new spirit-jar ; but as the jar has to be closed with a cork, and 
it is desirable to avoid the contact of the water with the organic 
matter of the cork, the better plan is to send the water in 
so-called Winchester quarts, which glass-stoppered half-gallon 
bottles can be bought at about Is. a-piece in any druggist's shop. 
Before being charged with the sample of water, the bottles 
should be filled to overflow with the water, the contents poured 
away, and again be filled with the same water up to the neck. 
The glass stopper should then be tied over with a piece of stout 
clean paper, calico, or leather, and the string sealed, if necessary. 
Impurities in Water. 
As stated already, in forming an opinion of the sanitary quality 
of a water, or the merits of a number of samples of potable waters, 
particular care should be bestowed on the examination of the 
amount and character of the organic impurities which the water 
may contain. 
In towns, no less than in the country, shallow well-waters are 
