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 now to be concentrated by evaporation at a temperature not exceeding 180° F., and subjected to the tests for meconic acid, more particularly to the action of perchloride of iron, when the quantity is small. If there is evidently a considerable quantity of acid, a portion should be evaporated till it yields crystalline scales; and these are to be heated in a tube to procure the arborescent crystalline sublimate formerly described. About a sixth of a grain of meconic acid, however, is required to try the latter test conveniently.

If the method of separating meconic acid by means of sulphuric acid be preferred, the precipitate formed by acetate of lead is to be treated with weak sulphuric acid, which forms insoluble sulphate of lead, and disengages the meconic acid. The liquid obtained by filtration is then to be evaporated as above, to obtain crystals, which are to be examined by the tests for meconic acid. Orfila thinks this method more delicate than the mode by hydrosulphuric acid gas. I am inclined from my own experiments to doubt his statement.

5. If there be a sufficiency of the original material, Merck's process for detecting porphyroxin may be tried [see p. 534]. But I doubt whether this process is sufficiently delicate for medico-legal purposes.

I wish I could add my testimony to the opinion, expressed on a remarkable occasion by Professor Chaussier, in favour of the delicacy of the tests for morphia and its compounds, that they might be detected "jusqu'à une molécule." In one sense this statement may be correct. Morphia, separated from the complex mixture of principles with which it is combined in opium, may be detected in extremely small quantities. Accordingly, M. Lassaigne has supplied, for the discovery of acetate of morphia in mixed fluids, an excellent process, whence the chief part of the three first paragraphs of the preceding method for opium are borrowed; and from the facts stated by him in his paper, as well as from the experimental testimony of Professor Orfila, it appears that Lassaigne's process will furnish strong indications, if not absolute proof of the presence of that salt, in the proportion of two grains to eight ounces of the most complex mixtures. Hence the search for acetate of morphia in a suspected case is by no means hopeless. But the detection of acetate of morphia is an object of small moment, compared with the detection of morphia in its natural state of combination in opium. Now my own observations lead me to entertain serious doubts, whether the best method of operating hitherto known could be successfully applied to the detection of the equivalent opium in complex mixtures. By the process I have recommended it is easy to procure, from an infusion of ten grains of opium in four ounces of water, satisfactory proof of the presence of morphia by the action of ammonia, perchloride of iron and nitric acid, and equally distinct proof of the presence of meconic acid by perchloride of iron, as well as sulphate of copper. But on proceeding to apply the process to organic mixtures, I have found that when the soluble part of ten grains of opium was mixed