قراءة كتاب Asbestos, Its production and use With some account of the asbestos mines of Canada

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Asbestos, Its production and use
With some account of the asbestos mines of Canada

Asbestos, Its production and use With some account of the asbestos mines of Canada

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دار النشر: Project Gutenberg
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fibre alone is used.

A considerable quantity of it is made use of in England, in the manufacture of some valuable kinds of packing for engineering work, millboards, felts, lubricants, paint, and the like; but in England we lack in some degree the readiness which is found on the other side of the ocean, in the adaptation of new materials and new methods of work.

Whether it be that Englishmen are influenced by climatic or other causes, certain it is that they are slow to adopt new systems, to cultivate novel ideas, or to move out of old grooves. Consequently, when new materials, or even novel applications of those long used, are suggested, they ponder over them, hesitate, and weigh the chances, and in so doing not infrequently let slip valuable opportunities; whilst the keener and more enterprising American, once he sees the drift of the new matter, will, to use his own expression, "catch hold" at once. It by no means follows, however, that this is the fault of the manufacturers alone; they have naturally to gauge the requirements of their customers, and prefer to limit their make to what they know they can sell.

The finer kinds of asbestos, the strong fibres of which are of a pure white colour and of a fine silky texture, being at the same time free from silicic acid or metallic oxide, are comparatively rare; and, on account of their lubricating qualities, are especially valuable. This particular kind, I am told, is at the present time only to be found in Canada and some parts of the States. Whether this statement is correct or not, I am not in a position to say; but that it is found in Canada I know, for I have there personally witnessed the blasting out of many hundreds of tons. In the Dominion it is invariably obtained from hard rock somewhat difficult to work.

In an interesting paper on Italian asbestos, to be found in the "Journal of the Society of Arts" for April, 1886, to which I have been indebted for a good deal of information respecting the Italian mines, I find a very singular statement given as the result of long observation by the employés of the United Company in Italy. It is there said that "if asbestos be found on the surface of a rock exposed either to the south or south-west, the product is generally fairly abundant and of good quality. If exposed to the east there is fine quality, but very small quantity; whilst if exposed to the north the quantity is plentiful but dry and hard, and on entering the rock all traces of it are lost."

Whether this be at all consistent with Canadian experience I cannot say. The lie of the ground and the course of the veins being so different, it is quite possible the theory may have no applicability at all to Canadian mining. But it is certainly suggestive and interesting, and I will cause inquiry in this direction to be set on foot at once.

In the same paper I find the following given as analyses of the two varieties. The first is stated to be by Professor Barff, but by whom the latter was made does not appear. According to these there would be little doubt which was the most valuable for general manufacturing purposes, but as there is nothing to show what kind of Canadian ore was submitted for analysis, or by whom the analysis was made, you must take it as an analysis only, quantum valeat.

  ITALIAN. CANADIAN.
Lime and magnesia 37·84 33·20
Silica 41·69 40·90
Oxide of iron   3·01   5·75
Potash     ·85 traces
Soda   1·41     ·68
Alumina   2·57   6·60
Moisture evaporated at 100° C.   3·04
Loss on heating to white heat, water of hydration, and organic matter   9·56 12·50
Chlorine     ·25
Loss     ·03     ·12
  100      100     

Three distinct kinds of asbestos are said to be found in Italy, viz., Grey, Flossy, and Powdery. The grey is a long, fibrous variety, possessing, in addition to strength, the much-prized saponaceous quality; and this is mostly found in the two Alpine valleys of Valtellina and d'Aosta. The flossy, which has a smooth, silky appearance, but a dry feeling when touched, is found and worked in part of the chain of mountains which bound the valley leading from Susa to Turin, and at an elevation of about 8,000 feet above the sea level. This is the kind which is mostly used in the manufacture of gas stoves. It is commonly found in thicker seams than the grey, lying mostly in a horizontal direction, but dipping rapidly as the rock is entered. The third is a powdery kind, which, while possessing all the heat-resisting properties of the two others, crumbles in the hand when touched. This variety is found in the same range of mountains as that last mentioned, but at a much lower level; it appears to have been first brought to light by a landslip exposing to view a seam of it three feet wide. When first seen it is said to have had a pasty consistency, but on exposure to the air it dried and crumbled into powder.

Italian ore, generally speaking, is won by running driftways, or tunnelling into the face of the rock. In Canada the mineral is got out by open quarrywork, no tunnelling there being possible. The serpentine rock in which the asbestos or chrysotile is there found is so split and seamed in every conceivable direction by the veins and stringers that if tunnelling were attempted the first blast would inevitably bring the whole superincumbent mass down about your ears. You might as well attempt to tunnel through loose sand or gravel. In other words, the relative difference in the two modes of winning the ore appears to be that the Italian asbestos may be said to be won by tunnelling into the face of the rock; whilst the Canadian chrysotile is found in veins, running, it is true, with the greatest irregularity, but yet with a distinctly perpendicular declension. The Italian variety, again, seems frequently to be found, or the seams to end, in pockets, some of which have been known to contain a ton or a ton and a half of asbestos, after exhaustion of which all appearance of its presence ceased. The Canadian ore, on the other hand, generally runs in veins and seams, which almost invariably improve both in quantity and quality the lower you go down, but where or how it ends has never yet been discovered.

It may possibly be, however, that the more correct way to put this would be the very opposite of what I have just stated; because if you stand and face the rock when laid bare in any of the Canadian mines and trace the downward course and increasing strength of the veins, it would really seem as if this strange mineral substance, at some former time, when in a state of violent ebullition, had striven energetically to force an outlet into the upper air, splitting the overlying rock in all directions in its passage upward from below; and that, as it gradually cooled off and expended its

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