These metals are infusible before the blowpipe. They are not volatile, nor are they oxidizable. Their oxides are, in both flames, reduced to a metallic and infusible powder. They give no reactions with fluxes, but are separated in the metallic form. These metals are generally found associated together in the native platinum, also with traces of copper, lead, and iron. The metal palladium is found native, associated with iridium and platinum. This metal generally occurs in greatest quantity in Brazil. The metal rhodium is found along with platinum, but in very small quantities. Iridium occurs in nature associated with osmium, gold, and platinum, in the mines of Russia. Its great hardness has rendered it desirable for the points of gold pens. In South America this metal is found native, associated with platinum and osmium. The latter metal, associated with platinum and iridium, has been found in South America. As these metals will not oxidize or dissolve, they cannot be separated from each other by the blowpipe with the reagents peculiar to that species of analysis. It is true that colors may be discerned in the beads, but these tints proceed from the presence of small traces of copper, iron, etc. The ore of osmium and iridium can be decomposed, 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.