4 BULLETIN 245, U. S. DEPARTMENT OF AGRICULTURE. 
After five days’ incubation at 28 to 30° C. the plates were counted. 
The average counts of the duplicate plates were taken and converted 
into equivalents for 1 gram of dry manure by the use of the figures 
obtained from the duplicate 10-gram samples that had been dried at 
100° C. The results obtained by plating on the standard beef agar 
are comparative and serve to show the germicidal action of the 
chemicals on the majority of the bacteria present in the manure. 
Dr. Seemann, in the work at New Orleans, used a medium prepared 
from manure water, but the counts were practically the same as 
those on beef agar. 
CHEMICAL EXAMINATION. 
The manure samples were analyzed for solids, ash, ammonia, and 
nitrogen, using the methods of the Association of Agricultural 
Chemists (Wiley, 1908). The total nitrogen determinations were 
made by the Nitrogen Laboratory of the Bureau of Chemistry. The 
results obtained by the magnesium-oxid distillation method for 
ammonia, which are not reported in the table, although much higher, 
showed the same general tendencies as the figures obtained on the 
water extracts. 
Water extracts were prepared from each sample by taking 25 grams 
of the finely divided manure and adding 500 ec. ec. of distilled water, 
allowing them to stand for one hour, with occasional shaking. The 
solutions were filtered, and the following determinations were made: 
Water-soluble nitrogen, ammonia, nitrites, nitrates, and reaction. 
Ammonia was extracted by the Folin and Macallum (1912) aera- 
tion method and nesslerized. Nitrites were determined with the 
sulphanilic acid reagent, and nitrates by the reduction method 
with aluminum foil (American Public Health Association, Labora- 
tory Section, 1912). Nitrites and nitrates were not usually found 
in the samples examined, because the manure had not stood suffi- 
ciently long. The reaction was determined by taking 20 ¢. c. of the 
water extract, diluting with 200 c. c. of carbon-dioxid free water, and 
titrating with twentieth normal acid, using alizarin red as indicator. 
GENERAL ACCOUNT OF SUBSTANCES USED. 
Representatives of two groups of substances were tested during 
the season’s work, namely, (1) inorganie and (2) organic, including 
volatile and nonvolatile substances and some plant material. These 
substances are arranged in alphabetical order in the respective 
groups. 
INORGANIC SUBSTANCES. 
Of the inorganic substances, arsenical dip, chlorid of lime, Epsom 
salts, lime-sulphur, and sulphuric acid in three concentrations were 
used. 
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