Page:Popular Science Monthly Volume 36.djvu/542

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526
THE POPULAR SCIENCE MONTHLY.

Thus we are on the wrong road when we look for too ingenious means for developing the chest ; this result, precious above all, can be obtained without any complicated appliances, without any difficult process ; and if we had to formulate concise advice on this subject we should say:

When a young person has a narrow and flat chest, recommend running if he be a boy, or skipping if a girl.


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CANADIAN ASBESTUS: ITS OCCURRENCE AND USES.

By J. T. DONALD, M.A.,

PROFESSOR OF CHEMISTRY, MEDICAL FACULTY, BISHOP'S COLLEGE, MONTREAL.

ASBESTUS is a singular mineral, whose characteristics are well indicated in the various names by which it is known. The French Canadian miners call it pierre à coton i. e., cotton-stone. The Germans speak of it as Steinflachs, stone-flax ; and amianto, the Italian name, indicates that which is undefiled, in allusion to the fact that it may be cleansed by fire. Asbestus, the name by which it is generally known, is a Greek word, signifying endless, ceaseless, and points to its fire-resisting properties.

Asbestus is, then, a mineral occurring in a fibrous form, the fibers being so fine and flexible that they may be spun and woven as cotton and flax are ; and, moreover, the fabric so obtained is capable of resisting a very high temperature. Some varieties are said to have resisted a temperature of 5,000° Fahr. It must be noted, however, that although this mineral is infusible, except at extremely high temperatures, its fibers lose their flexibility and become brittle at a temperature only sufficiently high to deprive it of the water which forms a part of its composition.

By the mineralogist the term asbestus was originally applied to a finely fibrous form of hornblende ; but, as Dana adds, much that is so called is a fibrous form of serpentine. Most if not all the asbestus of commerce is fibrous serpentine. A recent analysis made in the writer's laboratory showed the following composition:

Silica 39·05 per cent.
Magnesia 40-07 "
Alumina 3·69 "
Oxide of iron 2·41 "
Water 14·48 "
Undetermined ·30 "
100·00

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This mineral has been known from very early times, but it is only within recent years that it has found any extensive application in the various industrial arts. In ancient Greece the bodies