60 Dr. Ure on Opium dnd its Tests, 



stomach of a man who had fallen a victim to these mur- 

 derous devices. Here the laudanum had been largely mixed 

 with strong beer, and was sensible to the smell, in the 

 liquor extracted by the stomach-pump. One portion of that 

 liquor, treated with acetate of lead, afforded an insoluble pre- 

 cipitate, from which an acid, strongly-reddening permuriate of 

 iron, was separated by the agency of the sulphuric. Another 

 portion afforded directly, with a few drops of the permuriate 

 of iron, an evident reddish-brown tinge, very different from the 

 drab or fawn-coloured precipitate occasioned in strong beer 

 of the same quality by the same salt of iron. Other experi- 

 ments were made, which it is unnecessary to detail at present. 

 The chemical facts, joined to a body of circumstantial evi- 

 dence, led to a conviction of the guilty pair, a man and wife, 

 who were accordingly executed. 



It was suggested, by the ingenious counsel for the culprits, 

 that muriate of iron, as a test for opium, was fallacious, since 

 it would give the same redness with sulpho-cyanic acid, a 

 substance present in human saliva, as it does with the meconic 

 acid of opium. I was not then aware that this curious acid, 

 of modern discovery, did exist in the saliva, and thought it 

 merely a ruse de plaideur. But, even if ambiguity had been 

 occasioned by this test, the characteristic smell of opium 

 could not be set aside. 



Since that period, the elaborate work of Tiedemann and 

 Gmelin, Sur la Digestion^ has come in my way, which con- 

 tains proofs, apparently sufficient, of the existence of sulpho- 

 cyanate of potash in the saliva of man. Treviranus, indeed, 

 in his *' Biologia," published in 1814, had remarked that the 

 human saliva gave a sensible redness to the permuriate of 

 iron. 



I have recently repeated and varied Gmelin's researches, 

 and have found them entitled to confidence. My own saliva, 

 and that of many other persons, in its natural flow, as well as 

 provoked by smoking tobacco, acquires a blood-red hue, with 

 a few drops of permuriate of iron, such as would give to water 

 merely a faint, straw-yellow tinge. Saliva, simply distilled in 

 a glass retort, at a gentle heat, which did not brown a particle 

 pf the mucus, afforded a colourless water, that reddened lit- 

 mus paper, and grew red with a few drops of the ferreous salt. 



