Dr. Ure on Opium and its Tests. 63 



diffused through water, becomes, with a few drops of permu- 

 riate of iron, a greenisli liquid, quite different from the diluted 

 porter treated in the same way. 



Porter becomes turbid when supersaturated with water of 

 ammonia, and lets fall a brown sediment, which, collected and 

 washed on a filter, bears some resemblance to impure morphia, 

 but possesses a very remarkable peculiarity : it neither reddens 

 with nitric acid, nor does it suffer morphia mixed with it to 

 be thereby reddened, or at least the redness is merely momen- 

 tary, and passes on the slightest heat into a light yellow shade. 

 This precipitate I shall make the subject of future researches. 

 Tincture of hops, which becomes slightly turbid on mixing 

 with water, is rendered limpid by supersaturation with am- 

 monia. 



It might be imagined that bone-black (animal charcoal) 

 would decolour porter, so that the agency of permuriate of iron 

 on its supposed meconic acid might be made more manifest ; 

 but this process is at best fallacious ; since bone-black, boiled 

 with a portion of dilute solution of opium, deprives it almost 

 entirely of the power of affecting permuriate of iron ; while the 

 corresponding portion receives from that salt a deep red-brown 

 colour. 



Whenever morphia can be obtained apart, its identity may 

 be determined by decisive characters ; the bright red colour 

 imparted by it and its acetate to nitric acid, and the greenish- 

 blue tint, to red muriate of iron. 



I have not found the tincture of galls the delicate re-agent 

 for morphia, even to ij^^j^ part, which Dublane, the suggester 

 of this test, announced. It affords, with a solution of acetate 

 of morphia, a grey precipitate, which reddens with a drop of 

 nitric acid ; but tincture of galls cannot be used where gelatine, 

 and other animal matters, attractive of tannin, are present. 

 Even aided by alcohol, prescribed by Dublane for dissolving 

 out the tannate of morphia from the tannates of gelatine and 

 albumen, it will not answer ; for Vauquelin tried, in this way, 

 two portions of urine, one; which contained morphia, and the 

 other not ; and he had the same result from both — because 

 alcohol dissolves a great deal of the animal matter precipitated 

 by the tincture of galls, and thus complicates the experiment. 

 Glasgow, Dec. 19, 1829. 



