GUTTA-PERCHA PIPES AND TUBES.
Water-pipes have had a few vicissitudes in their history. Those who remember the arrangements for the water-supply of London, in past days, will have been familiar, with the wooden pipes, formed of bored trunks of trees, which were wont to be laid down beneath the paving of the streets. These gave way to iron. The smaller pipes have chiefly been made of lead; but zinc in one quarter, brown ware in another, glass in another, have invaded the domain of lead. A new competitor now enters the field. Gutta-percha claims to be not merely an efficient material for water-pipes, but to possess certain sanitary qualities very important in this sanitary age of ours. It is very strong and tough (say the patentees); it possesses much durability underground; it stoutly resists frost; and it leaves the water as pure as it finds it. Hence it is applied to pump barrels, to ships’ pumps, to locomotive feed-pipes, to syphons and mine-pipes, and to fire-engine pipes. But if the testimony of medical men is to be deemed authoritative, the substitution of gutta-percha for lead as a material for water-pipes is a matter of yet higher import. Dr. Thomas Smith, of Cheltenham, states that “Many serious and alarming disorders, such as mania, epilepsy, sudden death, nervous affection, paralysis, consumption, hydrocephalus, heart disease, &c., owe their origin in some instances, their intractable character in others, to the gradual and continuous infinitesimal doses of lead, copper, &c., introduced into the system through the channel of our daily drink.” It appears that the carbonic acid contained in water has a tendency to combine with the lead of the pipe which contains it, and to generate a compound possessing poisonous qualities. That gutta-percha resists such action, all authorities agree; and although at first the gum imparts a slight taste to the water, this effect seems speedily to disappear.
There are many other circumstances which render tubes of this material very advantageous for the conveyance of water. It bears an amount of friction and hard usage which is frequently surprising. At New York there is a gutta-percha pipe a thousand feet in length, which conveys the water of the great Croton Aqueduct to Blackwell’s Island; the pipe lies along the bed of the intervening river, and is kept down by upwards of a hundred small anchors, and yet it resists both the friction of the bed and the weight of the anchors. With an immense pressure of water, gutta-percha pipes have been found to remain unharmed, where leather hose would be disrupted. It resists the action of marine insects, which would soon make ravages on stout timber. If water be contained in a gutta-percha pipe, it remains liquid at a temperature which would produce ice in almost any other pipes. For watering gardens and roads, for sprinkling malt in a kiln, for applying water from a fire engine, these pipes appear to be singularly well fitted, since, with a great power of resisting pressure, they may be bent, or twisted, or lengthened, or shortened, in any required degree. Nor is this material, per se, the only efficient part of such pipes; for a gutta-percha pipe may be firmly united to a metal pipe in five minutes, with no other cement than warm water; the end of the pipe being softened in warm water, and drawn over the end of the metal, the gum contracts on cooling so as to grasp the metal tightly, and thus form an impenetrable joint.
But if water be conveyed thus effectively through tubes of gutta-percha, the qualities of the material are still more remarkably displayed in the conveyance of chemical liquids. Few persons are so ignorant of chemistry as not to be aware that the stronger acids and alkalies play sad havoc with the vessels and tubes which contain them. On the other hand, there is an obstinacy of constitution about this singular substance which enables you to battle a whole host of formidable opponents. It does yield, certainly, to concentrated sulphuric and nitric acids; but if these acids in a weaker state be the liquids in question, or if muriatic, acetic, or hydrofluoric acids, or chlorine (all of which have a very destructive action), then the gutta-percha stoutly resists them, and renders good service. Carboys, pipes, dye-vats, flasks, funnels, bowls, ladles, syphons, troughs, measures, buckets—all are now made of this material, for use in chemical works, print works, dye and bleach works, and other establishments where strong chemical liquids are employed.
CEMENT EXPERIMENTS.
The chemistry of cement is a curious one; for the stony particles adhere with a force which is in some instances almost equal to the power of stone itself. The so-called Roman cement has long been famous for its cohesive property; but the Portland cement recently introduced far excels it. In an experiment lately conducted, two solid blocks were prepared, one of Roman and the other of Portland cement; and they were placed in such positions that weights might be suspended from them. The Roman cement yielded to a disruptive force of eleven hundred pounds, but the Portland cement stoutly maintained its integrity till rent asunder by a weight of nineteen hundred. But this cement has still more strikingly shown its strength when used as a mortar in brickwork. On a recent occasion in Hyde Park, a brick beam was built up with Portland cement as a mortar. The bricks were hollow, and were so ranged as to form a beam about four feet in height by two in width. This beam was rested at the two ends on supports more than twenty feet asunder, and weights were suspended from the centre; and not till the astonishing weight of nearly seventy thousand pounds was thus applied did the beam yield and break. It was not the actual binding power of the cement alone that resisted this enormous force, for thin slips of iron were introduced at different parts; but the experiment was intended to show how much strength might be obtained by hollow bricks and Portland cement, aided by a little iron.
STEREOTYPING FROM GUTTA-PERCHA.
Mr. Muir, of Glasgow, has invented a mode of stereotyping, managed in the following way. A page of common type is first set up, and well fixed: a warm cake of gutta-percha is applied to it, screwed down tightly, and allowed so to remain a quarter of an hour; when this gutta-percha mould is removed, it is brushed over with fine black-lead, and an electro-copper cast taken from it; the printing is then effected from this cast. It is found that gutta-percha constitutes a very convenient and efficient substance for the mould, owing to the readiness with which it can be softened, and its toughness when cold; while the electro-copper cast is said to bear the action of the printing press throughout a much greater number of copies than an ordinary stereotype plate.
The same inventor also practices a plan in which the gutta-percha performs not only its own work but that of the electro-copper also. A mould is taken from an engraved wood-block, in gutta-percha; and this mould, when brushed over with black-lead, is made to yield a cast also in gutta-percha, in an exactly similar way; and from this cast the impressions are printed. It seems difficult to conceive that, after this double process, all the delicate lines of a wood engraving should be preserved on the surface of such a material as gutta-percha; and yet, without this preservation, the method would be practically valueless.