SYNOPTICAL TABLE OF THE MINERALS.

Sulphur is found in Sicily and Italy and other parts of Europe, in a native state, but as such has to be purified. The crystals take the form as shown in the margin. Cleavage imperfect; it is brittle. Sulphuric acid is a very important combination, and a very dangerous one in inexperienced hands. Sulphur combines with a number of elements, which combinations are “Sulphides.” (See [Chemistry section].)

Fig. 457.—Crystals of sulphur.

Selenium is a metalloid resembling sulphur, but less common. It is inodorous.

Boron is usually found near volcanic springs, and in combination with oxygen. It is soluble. Taste, acid bitter, and white in colour; friable. It is known as Sassoline, or boracic acid. (See [Biborate of Soda] for one of the borates.)

Carbon is one of the most important of our minerals. In the form of coal we have it in daily use, and in the form of diamond it is our most valuable gem. In the latter form it is the hardest of all minerals, a powerful refractor of light, lustrous, and transparent. It is found in the East Indies and Brazil; more lately Cape diamonds have been brought to Europe, but they do not equal the Eastern gem. Almost fabulous prices have been given for diamonds, which, after all, are only carbon in a pure state. Another form of carbon is graphite (plumbago, or blacklead). It is much used for pencils and in households. It is found in Cumberland, and in many other localities in Europe and Canada.

Carbon appears in one or other of the above forms in regular octahedrons or their allied shapes. Anthracite, another form of carbon, is used as fuel for strong furnaces. It leaves little “ash,” and is smokeless when burned. Coal, in all its forms, is evidently derived from wood. Thousands of years ago vegetable matter must have been embedded in the ground and subjected to carbonization. There are different kinds of coal, all of which come under one or other of the following heads: cubical coal, slate coal, cannel coal, glance-lignite,—the last being, as its name implies, an imperfect development of wood; it is a brown coal. We are not here concerned with coal as a fuel. Charcoal is also a form of carbon prepared from wood and finds a counterpart in coke, which is prepared from coal. Carbon, as we have already seen, plays an important part in electric lighting and in the Voltaic Battery. Peat, or as it is called in Ireland, “turf,” is one of the most recent of the carboniferous formations. It is much used as fuel. It is cut from moors (“bogs,” as they are sometimes called), and the various deposits can be traced. Bog-oak is no doubt the first step towards peat, as peat is the step towards coal. The brown turf is newer than the black, and both kinds may be seen stacked in small square “bricks” along the Irish canals and in the yards of retailers of fuel.