sed, and the former
recognized by its fetid odor. This metal, strongly ignited in a glass
tube with nitrate of potash, is converted to the oxide of osmium,
which gives an odor not unlike the chloride of sulphur.

As the metals of this group are very rare ones, especially the last
four ones, we shall not devote an especial division to each of them.
For a more detailed statement of their reactions, the student is
referred to the large works upon blowpipe analysis.

CLASS III.

NON-METALLIC SUBSTANCES.

1. _Water_--2. _Nitric Acid_--3. _Carbon_--4. _Phosphorus_
--5. _Sulphur_--6. _Boron_--7. _Silicon_--8. _Chlorine_
--9. _Bromine_--10. _Iodine_--11. _Fluorine_--12. _Cyanogen_
--13. _Selenium_.

(1.) _Water_ (HO).--Pure distilled water is composed of one volume of
oxygen, and two volumes of hydrogen gases; or, by weight, of one part
of hydrogen to eight parts of oxygen gases. Water is never found pure
in nature, but possessing great solvent properties, it always is found
with variable proportions of those substances it is most liable to
meet with, dissolved in it. Thus it derives various designations
depending upon the nature of the substance it may hold in solution, as
lime-water, etc.

In taking cognizance of water in relation to blowpipe analysis, we
regard it only as existing in minerals. The examination for water is
generally performed thus: the substance may be placed in a dry tube,
and then submitted to heat over a spirit-lamp. If the water exists in
the mineral mechanically it will soon be driven off, but if it exists
chemically combined, the heat will fail to drive it off, or if it
does, it will only partially effect it. The water will condense upon
the cool portions of the tube, where it can be readily discerned. If
the water exists chemically combined, a much stronger heat must be
applied in order to separate it.

Many substances may be perhaps mistaken for water by the beginner,
such as the volatile acids, etc.

(2.) _Nitric Acid_ (NO^{5}).--Nitric acid occurs in nature in potash
and soda saltpetre. These salts are generally impure, containing lime,
as the sulphate, carbonate and nitrate, and also iron in small
quantity. The soda saltpetre generally contains a quantity of the
chloride of sodium. The salts containing nitric acid deflagrate when
heated on charcoal. Substances containing nitric acid may be heated in
a glass tube closed at one end, by which the characteristic red fumes
of nitrous