300 POISONS : THEIR EFFECTS AND DETECTION. [§ 362. 
sulphuric acid ; the acid must be added until the yellow colour dis¬ 
appears and a colourless solution is obtained ; morphine warmed with 
a few drops of this solution produces a fine green colour, or, if the 
solution is diluted, a bluish-green colour. 
7. Tungstic Acid Test. —A solution of anything like 1 per cent, of 
sodium tungstate is inapplicable ; but if a dilute solution of the salt is 
taken (say 1 mgrm. per c.c.) and acidified with sulphuric acid, the 
solution gives a violet colour with morphine or morphine salts. 
8. Titanic Acid Test; —Titanic acid is dissolved in strong sulphuric 
acid by the aid of heat; the solution should be syrupy and clear. A 
drop of this solution added to solid morphine strikes immediately a 
black colour. 1 
9. Radulescu’s Reaction. —A solution of morphine in dilute sul¬ 
phuric acid is treated with a crystal or two of sodium nitrite. When 
gas has nearly ceased to be evolved, the liquid is made alkaline; a reddish- 
yellow to ruby-red colour is produced, intensity being proportional to 
the amount. This reaction is stated to be suitable for colorimetric 
estimation. 2 
Other Reactions. —There are some very interesting reactions besides 
those just mentioned. If a saturated solution of chloride of zinc be 
added to a little solid morphine, and heated over the water-bath for 
from fifteen minutes to half an hour, the liquid develops a beautiful and 
persistent green colour. This would be an excellent test for morphine 
were it not for the fact that the colour is produced with only pure 
morphine. For example, the reaction is not obtained from morphine 
in very well-formed crystals precipitated from ordinary laudanum 
by ammonia, the least trace of resinous or colouring matter seriously 
interfering. By the action of nitric acid on morphine, the liquid 
becomes orange-red, and an acid product of the formula C 10 H 9 NO 9 is 
produced, which, when heated in a closed tube with water at 100°, 
yields trinitrophenol or picric acid. On adding a drop of sulphuric 
acid to solid morphine in the cold, the morphine solution becomes 
a faint pink ; on gently warming and continuing the heat until the 
acid begins to volatilise, the colour changes through a series of brownish 
and indefinite hues up to black. On cooling and treating the black 
spot with water, a green solution is obtained, agreeing in hue with the 
same green produced by chloride of zinc. Yitali 3 has proposed the fol¬ 
lowing test:—Morphine is dissolved in strong sulphuric acid, and a little 
arsenate of sodium is added ; on gently warming, a passing blue colour 
1 0. Reichard, Ze.it. f. anal. Chemie, 1903, p. 95. 
2 R. Fabinyi, Ghem. Zeit., 1911. 
3 D. Vitali, Bull. Farrnaceut., Milano, 1881, p, 197 ; D. B. Dott, Year Book of 
Pharmacy , 1982. 
A good micro-chemical test for morphine is the action of iodine, which produces red 
plates (Earl B. Putt, J. Ind. Eng. Chem., 1912). 
