before the paper is introduced, the heat of the vapor will prevent the formation of the characteristic compound. The color may, of course, disappear after a while, by either heat, or an excess of chlorine.

bright, metallic iron-a knife-blade,
needle-becomes coated with metallic

If a quantitative determination of
desired, the solution is weighed, and a
portion of it used for the qualitative
maining portion is heated to ebull
oxide of copper precipitated by cau
precipitate is collected on a filter, was
ignited in a porcelain crucible until th
pletely consumed. It is then weighed
weight obtained, the whole amount
by calculation. Or, the whole of the
for this precipitation, and the weigh
wards dissolved in nitric acid and
the resulting liquid is then used for
tests. After having precipitated wit
the liquid usually retains a blue co
original precipitate of sulphide of
collected on a filter, and if chlorate
used for the destruction of the organ
this case, a little grape-sugar (honey)
the last trace of copper is precipita
oxide; by ignition it passes into prot

$63. Lead.-If the precipitate, phureted hydrogen, consisted of sul becomes decolorized by the action Some sulphuric acid (and, if necessa of potassa) is added, and the who dryness. On adding water to the powder, sulphate of lead, remains u The contents of the dish are ne conical glass; the powder is allov

CHAPTER VII.

ON THE DETECTION OF POISONOUS ALKALOIDS.

$103. CASES of poisoning with alkaloids are of comparatively rare occurrence [in countries where the laws of a well-regulated medical police restrict the sale of these dangerous drugs. In England, and in this country, where such restrictions are wanting, very many cases of fatal poisoning with these substances are known, at least a sufficient number to make the knowledge of exact and reliable methods for their detection, appear very desirable.]

For some alkaloids, when in the pure state, we have very characteristic tests, not less so than for the inorganic poisons; thus, for instance, for strychnine and morphine; but the separation, in the pure state, of very minute quantities of these poisons from the contents, food, etc., requires a very high degree of practical knowledge, and a most practiced hand; and yet, their separation in the purest condition possible, is necessary; because a very minute intermixture of any foreign substance, frequently renders the tests used for their detection fallacious.

For other alkaloids, again, we are utterly destitute

of characteristic tests; and in such cases we must consider ourselves very fortunate, if we can show that there is any alkaloid present. To ascertain the poisonous effect of the separated alkaloid, the quantity obtained is usually too small, and with regard to the chemical tests, it must be borne in mind, that the alkaloids show, in this respect, a great similarity.

It is a very fortunate circumstance, that in the majority of cases there is but very little doubt in regard to the nature of the poison employed, and all that remains to be done by the legal chemist, is to show that the poison really existed in the body, etc. For this reason, the chemical examination has, not unfrequently, more a scientific than a practical interest.

104. The separation of the alkaloid, in the purest possible condition, is, as mentioned above, to be aimed at before all other things; to ascertain its nature, constitutes the next step. Of the alkaloids which may become the objects of our investigation, some are volatile, as nicotine, conicine, etc., others non-volatile, as morphine, strychnine, veratrine, etc. We shall commence with describing their most characteristic properties and tests.

Nicotine. It is a colorless, oily liquid, becoming yellow on exposure to air, of acrid taste, and of a faint odor; it is usually said to possess the odor of tobacco, but I should rather call it an ethereal odor, which is most distinctly noticed in the dilutę state. It is readily soluble in ether and alcohol; water and alcohol dissolve it in considerable quantity. The alcoholic solution affects tumeric-paper. On distillation with