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ACIDIM HYDRI0DICU3I DILLTU3I. 
Diluted Hydriodic Acid. 
HI 
'‘A solution of hydriodic acid containing not less than 10 per cent 
b}" weight of the absolute acid, and about 90 per cent of water.” 
This is a reintroduction, the preparation haying been admitted to 
the U. S. Pharmacopoeia of 1860, but dismissed on account of the 
difficulty of preserying it. 
In the present preparation there is a small quantity of hypophos- 
phorous acid. This acts as a preseryatiye by reducing an}" iodine set . 
free to hydriodic acid. The method of preparing it (for which see the 
Pharmacopoeia) is that recommended in the 1890 U. S. Pharmacopoeia 
in connection with the preparation of Syrupus Acidi Hydriodici; the 
latter is now prepared from the Acidum Hydriodicum Dilutum. The 
method is simple and requires no special apparatus or chemicals. 
Character. — A clear, colorless liquid, odorless and haying an acid 
taste. It should not become colored on keeping. Miscible in all 
proportions with water or alcohol. 
Dose. — ‘‘Ayerage dose: 0.5 Cc. (8 minims).” (U. 8. P. ) 
Caution. — “Should be kept in small, amber-colored, glass-stoppered 
bottles, protected from the light.” 
ACIDU3I HYPOPHOSPHOROSOI. 
Hypophosphorous Acid. 
HPH,0, 
“A liquid composed of 30 per cent by weight of absolute hypophos- 
phorous acid and 70 per cent of water.” 
Properties. — A colorless, odorless liquid having an acid taste. Alis- 
cible in all proportions with water. It is a powerful reducing agent, 
precipitating metallic silyer from solutions of silyer nitrate, calomel 
from corrosiye sublimate, etc. ; when heated with copper sulphate a 
yellow precipitate of copper hydride is formed (difierence from phos- 
phorous acid). 
It is used in the preparation of Acidum Hypophosphorosum Dilutum. 
Incompatibilities. — Incompatible with arsenical salts, and in general 
with substances that are more or less easily reduced*. 
ACIDL3I TRICHLORACETICU3I. 
Trichloracetic Acid. 
CCI 3 .COOH 
“A monobasic organic acid usually obtained by the oxidation of 
hydrated chloral with nitric acid.” 
Properties. — White, deliquescent, rhombohedral crystals, haying a 
slight, characteristic, mildly pungent odor. 
