MORPHINE. 
§ 362.] 
299 
§ 362. Tests for Morphine. —1. One-hundredth of a milligrm. of 
pure morphine gives a blue colour to a paste of ammonium molybdate 
in sulphuric acid ; 20 mgrms. of ammonium molybdate are rubbed with 
a glass rod in a porcelain dish, and well mixed with 5 drops of pure 
strong sulphuric acid and the morphine in a solid form applied ; titanic 
acid and tungstates give similar reactions. 
2. Morphine possesses strong reducing properties; a little solid 
morphine dissolved in a solution of ferric chloride gives a Prussian 
blue precipitate when ferricyanide solution is added. A number of 
ptomaines and other substances also respond to this test, so that in itself 
it is not conclusive. 
3. Robert’s Test. —2-3 drops of formalin are mixed with 3 c.c. of 
strong H 2 S0 4 ; this reagent is mixed in a watch-glass with the dry 
substance. Morphine becomes purple-red, then violet, then clear blue. 
The solution, examined spectroscopically, shows a band in the yellow and 
orange ; dionin, codeine, and heroine give similar reactions ; methylphen- 
morpholine gives an intense red colour. 
4. Iodic Acid Test. •— The substance supposed to be morphine is 
converted into a soluble salt by adding to acid reaction a few drops of 
hydrochloric acid, and then evaporating to dryness. The salt thus 
obtained is dissolved in as little water as possible—this, as in toxi¬ 
cological researches only small quantities are recovered, will probably 
be but a few drops. A little of the solution is now mixed with a very 
small quantity of starch paste, and evaporated to dryness at a gentle 
heat in a porcelain dish. After cooling, a drop of a solution of 1 part 
of iodic acid in 15 of water is added to the dry residue ; and if even the 
i’o.rrorr of a grain of morphine be present, a blue colour will be developed. 
Another way of working the iodic acid test is to add the iodic acid 
solution to the liquid in which morphine is supposed to be dissolved, 
and then shake the liquid up with a few drops of carbon disulphide. If 
morphine be present, the carbon disulphide floats to the top distinctly 
coloured pink. Other substances, however, also set free iodine from 
iodic acid, and it has, therefore, been proposed to distinguish morphine 
from these by the after-addition of ammonia. If ammonia is added to 
the solution, which has been shaken up with carbon disulphide, the pink 
or red colour of the carbon disulphide is deepened, if morphine was 
present; on the contrary, if morphine was not present, it is either 
discharged or much weakened. 
5. Lloyd’s Test. — A mixture of hydrastin and morphine mixed 
with a few drops of sulphuric acid develops after about five minutes a 
blue-violet colour. This reaction has been investigated by J. L. Meyer 1 
and shown to be almost distinctive. 
6. Vanadic Acid Test. —Vanadate of ammonia is dissolved in strong 
1 Ze.it. f. anal. Chemie, 1902, p. 576. 
