388 poisons: their effects and detection. [§ 452. 
Atropine forms colourless crystals (mostly in groups or tufts of 
needles and prisms), which are heavier than water, and possess no 
smell, but an unpleasant, long-enduring, bitter taste. The experiments 
of E. Schmidt place the melting-point between 115° and 115-5°. It is 
said to sublime scantily in a crystalline form, but we have been unable 
to obtain any crystals by sublimation ; faint mists collect on the upper 
disc, at about 123°, but they are perfectly amorphous. The B.P. gives 
as follows the characters of atropine :— 
“ Colourless acicular crystals. Soluble in about 500 parts of water, 
readily soluble in alcohol (90 per cent.), in chloroform and in ether. 
Melting-point 114-5° to 115-5°. Its aqueous solution has an alkaline 
reaction and powerfully dilates the pupil of the eye. 0*05 grm. dissolved 
in 5 millilitres of water acidified with hydrochloric acid yields with 
solution of auric chloride a lemon-yellow precipitate, which after re¬ 
crystallisation from boiling water acidified with hydrochloric acid has 
a minutely crystalline character, is dull and pulverulent when dry, and 
melts at 137° to 139° (distinction from hyoscyamine x ). 0-01 grm. 
with 5 drops of nitric acid yields, when evaporated to dryness in a water- 
bath, a residue scarcely yellow in colour, which after cooling assumes a 
violet colour on moistening with freshly prepared alcoholic solution of 
potassium hydroxide. 0-05 grm. dissolves in 1 millilitre of sulphuric 
acid without coloration, and the solution remains colourless on the addi¬ 
tion of 1 drop of nitric acid. 10 millilitres of a solution containing 1 
part of atropine in 80 parts of water slightly acidified with hydrochloric 
acid does not at once become cloudy on the addition of 4 millilitres of 
solution of ammonia (absence of apoatropine).” 
§ 452. Homatropine, C 8 H l4 N(0C0,TJ 7 H 7 0), a synthetic substance 
made by combining tropine and mandelic acid ; it is phenyl-glycolyl 
tropein. Melting-point 95-5°-98-5°. 
Homatropine hydrobromide is official, and is thus described in the B.P.: 
—“ White crystalline powder or aggregation of minute crystals. Soluble 
in about 6 parts of water and in about 18 parts of alcohol (90 per cent.), 
the solutions being neutral to litmus. Yields the reactions characteristic 
of bromides. An aqueous solution, 1 in 100, powerfully dilates the pupil; 
1 millilitre of this solution, made alkaline with solution of ammonia, 
shaken with chloroform, the chloroformic solution being then separated 
and evaporated, yields a residue which turns first yellow and then brick- 
red when warmed with 1-5 millilitre of a solution (2 in 100) of mercuric 
chloride in alcohol (60 per cent.). When treated with nitric acid and 
alcoholic solution of potassium hydroxide, a reddish-yellow colour is 
produced, not changing to violet (distinction from atropine).” 
Homatropine discs are official, and much used in ophthalmic practice ; 
each disc contains 0-65 milligrm. of homatropine bromide. 
1 Hyoscyamine meJts at 107 °— 108 °. 
