Chemistry and Physics. 491 
Class V.—Artificially prepared waters, made as above, with 
various forms of vegetable refuse from manufacturing or industrial 
ce omg 
ass VI. armaatoinlly: prepares waters, as above, made with 
mess (or partly animal) organ ¢ matters of natural origin, 
especially aah as are ‘kely to occur in connection with the con- 
tamination of drinking water. 
Class VI Artificially i Bab waters, as above, wei with 
animal refuse from manufacturing or industrial operation 
Class VIII.—Artificially prepared waters, as above, which 
had been ey d morbid products from certain diseases in the 
human subje 
Class 1X es in distilled water, of carefully determined 
amounts of pure organic substances of definite chemical compo- 
sition, 
The three methods, with various modifications of the same, for 
the cabacnualign of organic matter which were investigated 
were: 
Sol e “combustion process” of Frankland and nerenes 
(2) The “ eee wT In onia process ” of bg nklyn, Chapm 
and Smith; and he “ permanganate proc ” origina lly se 
ested by Fail dca in the forms paveniten by Tidy and 
ubel respectively. 
e specimens of water, ap a under precisely similar condi- 
tions, were simultaneously examined by these methods in the 
hands of three independent snalyste, well nent for the work, 
one in Baltimore, one in Washington, and one at the University 
of Virginia—all quite ignorant of the history the character of 
the specimens pieipen ite to them viene Ssapaernane being desig- 
At the same pt a micr ic pe ig of each water was 
made and a pathological investigation ¢ of its effect (when concen- 
trated by evaporation at very low temperature) upon rabbits. 
by hypodermic injection, under the ‘direction of Profe essor H, 
Newell Martin, of the Johns Hopkins University. 
A detailed criticism of each of the m ihods cond] is given, 
noticing the special advantages and defects of each, with sugges- 
tions for the pegetien modification of these methods with a view 
to their improv 
e chie interes of this report in its complete i niger bc B 
the study by comparison with each other of the results give 
the series of tables, illustrating gored fully the "bearing of hes 
different conditions involyed—character of water e xamin , State 
in which its organic pit r was present when examined, precise 
conditions of application of the methods used, different character 
of the faite deducible from each of these, etc. 
important general conclusions arrived at as to the 
7 ahem pecans purposes of the different processes studied are 
the 
(1.) It is oe possible to decide absolutely upon the whole- 
