Page:The fairy tales of science.djvu/319

Rh "You are familiar with the general aspect and nature of coal, and are doubtless aware that it is almost wholly composed of the element, carbon. Were I to describe the immense varieties of coal that occur in nature, you would not thank me for my trouble, and would probably fall asleep long before I reached the end of my list. These different varieties of coal may, however, be grouped under three heads:—anthracite, ordinary or pit coal, and brown coal or lignite.

"Anthracite is a natural coke or charcoal, and may be regarded as the most completely mineralized form of coal. If you handle a piece of this substance, you will find that it does not soil the fingers like ordinary coal, that it is much heavier, and that it has a glistening and semi-metallic aspect. It is not easily ignited, but when burning gives out a fierce heat, and neither flames nor smokes.

"Ordinary coal has many varieties, which, however, may be classified into four kinds. The first kind is called caking-coal, from its fusing or running together on the fire, so as to form clinkers. Splint or hard coal comes next, which is not easily broken, nor is it easily kindled, though it affords a clear and lasting fire when once ignited. Cherry or soft coal, is an abundant and beautiful kind, and highly prized by mortals. It does not cake when heated, it can be broken with ease, and it readily catches fire, requiring but little stirring, and giving out a cheerful flame and heat. Another kind is called