is about the specific gravity of a sample of bourno

nite.

We have now the second case to consider; the mineral may be in very small fragments, or it may even be in powder, in which case its specific gravity must be determined thus :

A bottle must be obtained capable of holding a known quantity of water, as 500 grs. The ordinary specific gravity bottle is well suited for this purpose. A known weight of the body whose specific gravity is to be ascertained, say 100 grs. is to be introduced into the bottle, which is then to be filled with water, and the weight of the whole to be determined, it will be less than the united weight of the contents of the bottle full of water and the weight of the mineral in air. The loss of weight is to be ascertained, and the weight in air divided by it; the quotient is the specific gravity required. The following example may suffice to render this clearer :

Suppose the bottle contains of water
And the mineral introduced into it weighs

500 grs.

100 grs.

Then 100 =

40

2.5 required specific gravity.

Besides ascertaining hardness, fusibility, and specific gravity, it is required to determine the re-actions of the mineral with the various fluxes. The method of doing this has already been described. Finally, it is necessary to ascertain the behaviour of the mineral

in solution, or otherwise, with certain liquid re-agents. The method of conducting this class of examination will be pointed out in a following chapter.

Having thus given a rough sketch of the processes to be employed, we will now describe the whole method to be followed in ascertaining the nature of certain minerals, principally confining ourselves to those generally met with, and worked by the miner. The following is a list of them.

Amalgam.

Anhydrite.

Anhydrous silicate of zinc.

Grey antimony.

Native antimony.

Native mercury.

Red antimony.

Oxide of antimony.

Antimonial nickel.

Antimonial silver.

Antimonial grey copper.

Dark red silver.

Muriate silver, (horn silver.)

Native silver.

Sulphuret of silver.

Argentiferous gold.

Argentiferous grey cop

per.

Arseniate of cobalt.

Arseniate of copper.

Native arsenic.

Arsenic glanæ.

Oxide of arsenic.

Red sulphuret of arsenic.

Yellow ditto.

Arsenical iron.

Arsenical cobalt.

Arsenical nickel.

Arsenical pyrites.

Arsenical grey copper.

Arsenical bismuth.

Arsenious acid.

Arsenic acid.

Light-red silver.

Muriate of copper, (Ata

kamite.)

Azure copper ore.

Azurite.

Azure stone.

Carbonate of baryta.

Sulphate of baryta.

Arseniate of iron.

Bismuth blende.

Arseniate of lead.

Native bismuth.

CLASS I. MINERALS POSSESSING A METALLIC

LUSTRE.

CLASS II. METALS POSSESSING NO METALLIC LUSTRE.

These classes are further divided thus:

CLASS I.

Division 1. Metals proper.

Division 2. Fusible 1-5, or readily volatile.

Division 3. Infusible, or fusibility above 5, and not

volatile.

CLASS II.

Division 1. Easily volatile or combustible.

Division 2. Fusible 1-5; not, or only partially volatile. Division 3. Infusible, or fusible above 5.

Division 1.

CLASS I.

Metals proper, readily distinguished.

Division 2.

CLASS I.

Section 1. Give an arsenical odour on charcoal. Section 2. Give the horse-radish odour of selenium. Section 3. Give a white sublimate in open glass tube, which is fusible into colourless drops, indicative of tellurium.

Section 4. On charcoal give antimonial vapour.

Section 5. With soda give a sulphuret, but do not give indications as above.

Section 6. Behave differently to five preceding.

Section 1. Give the re-action of manganese with borax. Section 2. On charcoal in reducing flame become mag

netic.

Section 3. Partly agreeing with section 2.

CLASS II.

Division 1. Easily volatile or combustible.

Division 2. Part 1. Give on charcoal, either alone or with soda, a metallic bead or magnetic

Section 3. Give copper, and when moistened with

hydrochloric acid, colour the flame tran

siently blue.

1. Give a strong odour of arsenic.

2. Give no odour of arsenic.

Section 4. Give a bright blue with borax.

Section 5. Give a black or grey metallic magnetic mass, but not behaving as any of the

minerals of the preceding sections.

1. Indicate arsenic during fusion.

Section 6. Not belonging to either of the foregone sections.

Part. 2.

Give no metallic bead, or magnetic metallic

mass.

Section 7. After fusion, alone or with charcoal, have an alkaline reaction.

Division 3.

CLASS II.

Section 1. Ignited with nitrate of cobalt give zinc

re-action.

Section 2. Soluble in hydrochloric or nitric acids, giving no jelly or residue.

Section 3. Not included in the five preceding sections, but divided thus:

1. Hardness under 7.

2. Hardness 7, or above 7.