Asbestos

“ In the form of cement there is nothing equal to it as an efficient covering for boilers, steam pipes, hotblast furnaces, stills, &c. For this purpose it is made of about the consistency of mortar and spread on with a trowel in the ordinary way. Certain chemical ingredients have to be added, which, while not injurious to the metal, cause the asbestos to adhere firmly to the plates, so that when dry it becomes quite hard and can be walked over without being injured. ”

“ It is the transposition of the serpentine into Asbestos fibre, by the action of the atmosphere. This is to be seen on the dumps where the filling matter and cobbed rock is exposed. In one or two cases I have seen large quantities of broken rock changed into fibre after a few years, by atmospherical chemical agencies.
In so many cases I find people are prejudiced [14] from going deeper than a few feet from the surface, as not finding a copious supply of Asbestos there, when good indications are shown they become disheartened. ”

“ In many cases, the air was contaminated with a certain amount of gaseous material which would be likely to render the whole explosive, and if this got through the joint between the glass and the metal, there would be very serious risk of explosion. After a great number of substances had been tried and found unsatisfactory, some hundreds of experiments were made by Sir Frederick Abel and Sir Warington Smyth, with asbestos washers, which, in the end, were found to maintain their condition most admirably. ”

“ The asbestos is first coarsely ground, and then mixed with some granular crystalline carbonate, which must be soluble in acids. The carbonate should possess a hardness between 3 and 4, 5, according to the mineralogical scale. The mixture is ultimately ground together in a mill. Afterwards the mass is treated with an acid until the carbonate has been dissolved out. The escaping carbonic gas causes the asbestos fibres to be loosened and disintegrated from each [Pg 74] other so as to render the mass porous. ”

“ Having blasted the rock, the first process of extraction is termed "cobbing," which means breaking off the adhering serpentine from the Asbestos vein, this being manual work done by boys. The fibre is packed in sacks, each weighing 100 lbs., and in some cases 200 lbs. are shipped by the local railroad company to Montreal or New York at something about 10 cents and 20 cents per sack.
Asbestos is sorted into three qualities, and priced thus:—
Some inferior quality, at a very low price, is used by the Asbestos Mining and Manufacturing Company of Quebec. ”

“ In Fig. 185 we give a section of a Maignen filter. R is the reservoir for the filtered water; A the filter case proper; D a conical perforated frame; B a jacket of asbestos cloth secured top and bottom by asbestos cords to D; C powdered carbon, between which and the asbestos is a layer of special chemical filtering medium. A perforated cap, E, covers in the carbon and prevents it being disturbed when water is poured in. The carbon arrests the coarser forms of matter; the asbestos the finer. The asbestos jacket is easily removed and cleansed by heating over a fire. ”

“ Chrome iron is frequently found, sometimes as at Thetford and South Ham, in very large quantities in close proximity to the asbestos-bearing rock. In the iron, where this is the case, although the stringers of asbestos may be very minute, they will almost certainly be found intersecting the ore, just as we have already seen that the grains and threads of the chrome iron often cut and spoil the fibre of the asbestos.
The marketable value of asbestos is determined in the first instance by the colour, coupled with the thickness or width of the fibre in the vein. ”

“ In order to prove the efficacy of this apparatus, and inspire the firemen with confidence in its protection, he showed them that a finger first enveloped in asbestos, and then in a double case of wire-gauze, might be held a long time in the flame of a spirit-lamp or candle before the heat became inconvenient. A fireman having his hand within a double asbestos glove, and its palm protected by a piece of asbestos cloth, seized with impunity a large piece of red hot iron, carried it deliberately to the distance of 150 feet, inflamed straw with it, and brought it back again to the furnace. ”

“ If a few fibres of asbestos be ‘moistened’ with a saturated solution of bichromate of potash in oil of vitriol, and exposed to the smallest possible portion of hot alcohol vapour, it is almost instantly turned green, owing to the formation of oxide of chromium. In practice, the asbestos may be inserted in the neck of a retort, or even of a bulbed glass-tube containing a few drops of the suspected solution, when the effect occurs as soon as distillation commences. ”

“ The great objection to all the asbestos paper so far made is its want of toughness, its friability. The Journal of the Society of Arts makes mention of an asbestos paper covering for roofs, but, as this mineral is not proof against moisture as it is against fire, experience alone could determine its value for that purpose. But, perhaps, the most important service yet rendered by asbestos is the furnishing us with a fire-resisting packing for piston and pump rods, the necks of revolving retorts, etc. ”

“ An extraordinary specimen of Italian asbestos, obtained from one of the mines of the United Asbestos Company, situate in the Valtellina Valley, is in the possession of that company, and is no doubt the finest piece of asbestos ever brought from Italy, whether as regards strength or fineness of fibre. ”

“ 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. ”

“ Asbestos is not really any one particular mineral. It is the name given to several 44 minerals that occur in masses of slender, delicate fibers. In the more typical kinds of asbestos, these fibers—when pulled apart—resemble soft, fluffy, silk strings.
Several small deposits of amphibole asbestos have been found in the Llano uplift area of central Texas. This asbestos is a variety of the mineral tremolite, a calcium-magnesium silicate. It has fibers that break rather easily, and it has a silky luster. It is a shade of green or gray and gives a white streak when rubbed across a streak plate. ”

“ After the last wash-water is poured off, the asbestos is suspended in water and used for making the felt on the filter. The preparation of the crucible and the filtration under pressure are accomplished in the usual way.
The ignition of the precipitate is accomplished in a Rössler ignition oven, Fig. 5. When the muffle of the furnace shows a white heat or a white-red heat it is at the proper temperature for the estimation. At higher temperatures, the asbestos felt is easily injured. Generally, an ignition of five minutes is sufficient, but with double superphosphates, ten minutes are required. ”

“ In the Blue Book on the "Geological Survey of Canada, 1882" (Mr. Willimott's report) , published by the Dominion Government, it is stated that "there appears to be unlimited quantities of asbestos distributed throughout the entire serpentine belt which attains its greatest prominence in the townships of Thetford and Coleraine. Its existence is generally made apparent by a whitish shining substance found coating the serpentine, arising from the decay of the outcropping veins. But this," he says, "must not be taken as always indicating the presence of workable veins." ”

“ A permanent British monopoly of the mica market can probably best be obviated by the development of the Brazilian field by American electrical manufacturers.
Asbestos. —Asbestos is an essential mineral, on account of its incombustibility and insulating qualities, together with its fibrous structure, which enables it to be spun or woven into ropes and fabrics; and on this account it has a wide and varied use. There are mineralogically three kinds of asbestos—chrysotile, crocidolite, and anthophyllite—the last being, as a rule, of non-spinning quality. ”

“ In different varieties of asbestos the fibres vary greatly in character. When silky and flexible they are sometimes known as mountain flax. The finer kinds are often termed amianthus (q.v.) . When the fibres are naturally interwoven, so as to form a felted mass, the mineral passes under such trivial names as mountain leather, mountain cork, mountain paper, &c. The asbestos formerly used in the arts was generally a fibrous form of some kind of amphibole, like tremolite, or anthophyllite, though occasionally perhaps a pyroxene. ”

“ The use of asbestos in this way serves a twofold purpose. It retains the heat in the work and prevents the breakage that would follow if a draught of air were to strike the heated metal, and it also prevents such a radiation of heat through the surrounding air as would make it almost impossible for the operator to perform his work, especially in the case of large and heavy castings when the amount of heat utilized is large. ”

“ Similar severe trials of asbestos having occurred in Europe and America in our own times, the substance is being applied to various industrial purposes, such as roofing-cloth, incombustible dresses and fire-proof safes. ”

“ As regards the indications of Asbestos, it is a general recognised fact, and one that may be depended on, that not alone in Canada, but indeed all other places where Asbestos-bearing serpentine is found, the existence of Asbestos, or "Amianthus," is noticed when the serpentine is exposed, and presents a rusted, sometimes greyish and broken appearance, due to decomposition or weathering, or covered with a thin layer of soil. Small veins of Asbestos are to be seen forming a network on the surface of the rock. ”

“ An asbestos net, found at Monastero, used to wrap round the body during cremation and so keep the bones together, is interesting, as are lachrymatories misshapen by the flames, small bottles of rock-crystal beautifully cut, a few enamelled objects and carvings in ivory, principally children's toys. ”

“ The rapidly increasing favour with which high pressure steam is now regarded by engineers, recently necessitated the introduction of a packing capable of resisting the higher temperatures and pressures; as a consequence manufacturers of asbestos goods had to devise improved methods of manufacture in order to meet the new condition of things, and this they succeeded in doing in a way to give universal satisfaction.
For washers asbestos has many advantages over rubber; its weight is less, they can be frequently used, and half the thickness of rubber is mostly sufficient. ”

“ The outcroppings here, moreover, are far superior to anything that can be seen on the ground lower down where work is now being carried on. A practical mining engineer who was recently sent to examine and report on this property says that it is 100 per cent. better than that at Black Lake; that 75 per cent. of the whole is veritable asbestos-bearing land, and that he knows of no other asbestos mine so well situate for practical work, or showing such advantages in timber, water, and, dumping ground. The timber is sufficient for all practical purposes for at least twenty-five years. ”

“ Tournefort’s Travels, vol. i. p. 129. Bruckmann, Hist. Nat. Lapidis. Brunswic. 1727. p. 31, 32. This author says the asbestos was put into warm water, and there rubbed and turned about. An earth separates from it, which makes the water as white as milk. This is repeated five or six times. The fibres, thus purified, are spread out to dry.
Ignorance of the true nature of Asbestos caused it to be employed in the dark ages for purposes of superstition and religious fraud. Of this we have a proof in the following account [Pg 397] which we find in the Chronicon Casinense of Leo Ostiensis, L. ii. ”

“ Another important mineral product which even more than petroleum or coal is supposed to be essentially modern in its employment is asbestos. Polo had not only seen this but had realized exactly what it was, had found out its origin and had recognized its value. Curiously enough he attempts to explain the origin of a peculiar usage of the word salamander (the salamander having been supposed to be an animal which was not injured by fire) by reference to the incombustibility of asbestos. The whole passage as it appears in The Romance of Travel and Exploration deserves to be quoted. ”

“ When a sufficient number of holes of the proper depth are drilled and duly charged with dynamite or powder, they are linked together, and fired by a battery in such a way that the face of rock shall be thrown outward on to the floor of the pit. The asbestos is then picked out, the adhering rock roughly broken off, and the ore piled into boxes or tubs, which are loaded on to trolleys, and run off on tram-lines to the cobbing-sheds. ”

“ In one of the large palatial buildings recently erected in London, where engines are required to be in constant work for pumping water for working the lifts and for general purposes, as well as for the dynamos, the heat from the boilers forms so great a nuisance, and occasions so much loss in other ways, that very considerable expense is about to be incurred, with a view to lowering the temperature. When conversing recently with an expert on this subject I asked whether the use of asbestos would not effect the desired object. ”

“ The asbestos curtain was already on its way down, which should have been reassuring: but then asbestos curtains never look the part. To the lay eye they seem just the sort of thing that will blaze quickest. ”