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An account of apparatus and processes for the chemical and photometrical testing of illuminating gas
126
31Iechanlcs, Physics, and Chemistry.
large enough to contain perhaps a one or two horse-load of lime. Water is put into the pit, the lime is shoveled in gradually, while at the same time it is stirred to and fro with a mortar fork, and so on till the whole is dissolved to the consistency of thick cream; the stones of course settle at the bottom, and when the lime subsides the water is run off. In a short time a firm bed of putty is ready to make mortar of, then, or at any time within six months, if the lime-pit be protected from rain and sun. Of course a hard film or protective coating forms itself on the surface ; under this the lime remains fresh and mellow to almost an indefinite length of time. Of mortar made with lime so prepared, I can testify from twenty years experience to its hard-setting and durable qualities. It has never occurred to me totest exactly the qualities of this as compared with any other mortar prepared from freshslaked lime; but I may observe that the practice of making mortar from lime-putty, and in the rough-and-ready way above described, seems to be dictated by necessity rather thau choice. It prevails chiefly in the country where, from the great distance it has sometimes to be carted, it would be impracticable, for ordinary building purposes, to have fresh.slaked lime on every occasion. W.M.
Jtn J~ccount of Hpparatus and Processesfor the Chemical and Photome. trical Testing of Illuminating Gas. By Prof. W. B. Re,v as. From the London Xthenveum~ Oct. 1864.
The instruments and methods described in this communication are those adopted in the gas inspection lately organized by Prof. Rogers, for the State of Massachusetts ; comprising the measurement as well as testing of gas. Connected with the former of these objects, an account was given of the adjustments of the standing measure for gauging gasholders,--of a universal clamp for meter-eonnexions,--and of an appendage combining a delicate thermometer and pressure gauge for the inlet and outlet of the meter, and by which the rate of delivery is accurately adjusted. :For chemical testing, the eudiometer, consisting of a graduating tube, with cylindrical enlargement, is permanently enclosed in a wider tube full of water, which maintains the temperature nearly uniform. The mouth of the graduated tube is furnished with a hollow ground stopper, for holding the several liquid absorbents used in the successive experiments. With this apparatus it is easy to determine the percentage of carbonic acid, of illuminating hydrocarbons, of oxygen, and of carbonic oxide ; after which the hydrogen and light carburetted hydrogen are ascertained by explosion, by means of an instrument consisting mainly 9f two glass tubes, united below by a long loop of rubber-tube, being a modification of Frankland's apparatus. For determining the sulphur, an improved arrangement is used, Ja which the stream of water supplying the Liebig's condenser is made to convey ~ stream of air, mingled with ammonia, into the condensing tube some inches above the flame of the burning gas. To secure a larger and more constant unit of illumination than the candle common]y used~ ~ lamp burning kerasine, with a itat wick, is employed, in
On Boring Rocks.
127
which, by means of a bridge of platinum wire, the flame may be maintained of constant size, and giving a light equal to about seven candles. This is supported on a balance of peculiar construction, giving the consumption during the experiment. Profi Rogers had found that even the small amount of carbonic acid which in some gas-works is allowed to remain in the gas produces a sensible reduction of the light. This effect w~rying with the strength of the illuminating gas, was found to range from .~ to nearly 5 per cent. of the illuminating power for each per cent. of the impurity : 58 per cent. of carbonic acid, although it did not prevent combustion, made the flame so dim as to be without effect on the photometer.
On Boring ttocks. From the London Mechanics' Magaziuej December~ 186-1.
Sin'--The enormous outlay which attends the opening and working of mines in districts where the strata are, as in Cornwall, of an exceedingly hard nature, is due mainly to the slow progress which can be made in sinking shafts, or driving levels or headings through such refractory rocks. Thus £ 60 per fathom is not an unusual price for sinking a shaft in hard Cornish stone ; and even at this immense cost the progress made is very small. Iu solid limestone rock a shaft 9 feet in diameter can be sunk for .£ 7 per fathom, and at the rate of ten fathoms per month ; but a shaft in hard capal or roskear stone costs 2~ 60 per fathom, and perhaps not one fathom per month can be sunk. In each case, the labor is mainly accomplished by boring holes ia the rock, and firing them with charges of powder, the explosion of which bursts, and breaks up the rock. :Now in limestone these holes can be rapidly bored, because limestone is considerably softer than good hardened steel, and therefore the steel borer keeps its edge a long time, and cuts the rock keenly and quickly. But eapal or roskear stone is nearly and often quite as hard as the best hardened cast steel ; hence the edge of the borer is soon worn or beaten up, and in place of cutting the stone keenly, it merely bruises it away by degrees, making slow progress through it, and to enable even this to be done, the edge of the borer bit has to be made very thick and obtuse, and in a form the least calculated to penetrate rapidly. In boring a hole 8 inches in hard veinstone, upwards of 200 borer bits have had to be re-set by the smith, and the cost of each re-setting or tempering is fairly stated at about threepence for each bit, taking labor, loss of time, &c., &e., into consideration. Now, if a steel can be produced which, when hardened, will be as much harder than eapal or roskear stone as the best hardened steel at present made is harder than limestone, then by the aid of this steel shafts may be sunk and levels driven in the hardest ground as rapidly and as economically as can at present be effected into ordinary limestone rock. Such a steel can be produced, and I invite the attention of mining
31Iechanlcs, Physics, and Chemistry.
large enough to contain perhaps a one or two horse-load of lime. Water is put into the pit, the lime is shoveled in gradually, while at the same time it is stirred to and fro with a mortar fork, and so on till the whole is dissolved to the consistency of thick cream; the stones of course settle at the bottom, and when the lime subsides the water is run off. In a short time a firm bed of putty is ready to make mortar of, then, or at any time within six months, if the lime-pit be protected from rain and sun. Of course a hard film or protective coating forms itself on the surface ; under this the lime remains fresh and mellow to almost an indefinite length of time. Of mortar made with lime so prepared, I can testify from twenty years experience to its hard-setting and durable qualities. It has never occurred to me totest exactly the qualities of this as compared with any other mortar prepared from freshslaked lime; but I may observe that the practice of making mortar from lime-putty, and in the rough-and-ready way above described, seems to be dictated by necessity rather thau choice. It prevails chiefly in the country where, from the great distance it has sometimes to be carted, it would be impracticable, for ordinary building purposes, to have fresh.slaked lime on every occasion. W.M.
Jtn J~ccount of Hpparatus and Processesfor the Chemical and Photome. trical Testing of Illuminating Gas. By Prof. W. B. Re,v as. From the London Xthenveum~ Oct. 1864.
The instruments and methods described in this communication are those adopted in the gas inspection lately organized by Prof. Rogers, for the State of Massachusetts ; comprising the measurement as well as testing of gas. Connected with the former of these objects, an account was given of the adjustments of the standing measure for gauging gasholders,--of a universal clamp for meter-eonnexions,--and of an appendage combining a delicate thermometer and pressure gauge for the inlet and outlet of the meter, and by which the rate of delivery is accurately adjusted. :For chemical testing, the eudiometer, consisting of a graduating tube, with cylindrical enlargement, is permanently enclosed in a wider tube full of water, which maintains the temperature nearly uniform. The mouth of the graduated tube is furnished with a hollow ground stopper, for holding the several liquid absorbents used in the successive experiments. With this apparatus it is easy to determine the percentage of carbonic acid, of illuminating hydrocarbons, of oxygen, and of carbonic oxide ; after which the hydrogen and light carburetted hydrogen are ascertained by explosion, by means of an instrument consisting mainly 9f two glass tubes, united below by a long loop of rubber-tube, being a modification of Frankland's apparatus. For determining the sulphur, an improved arrangement is used, Ja which the stream of water supplying the Liebig's condenser is made to convey ~ stream of air, mingled with ammonia, into the condensing tube some inches above the flame of the burning gas. To secure a larger and more constant unit of illumination than the candle common]y used~ ~ lamp burning kerasine, with a itat wick, is employed, in
On Boring Rocks.
127
which, by means of a bridge of platinum wire, the flame may be maintained of constant size, and giving a light equal to about seven candles. This is supported on a balance of peculiar construction, giving the consumption during the experiment. Profi Rogers had found that even the small amount of carbonic acid which in some gas-works is allowed to remain in the gas produces a sensible reduction of the light. This effect w~rying with the strength of the illuminating gas, was found to range from .~ to nearly 5 per cent. of the illuminating power for each per cent. of the impurity : 58 per cent. of carbonic acid, although it did not prevent combustion, made the flame so dim as to be without effect on the photometer.
On Boring ttocks. From the London Mechanics' Magaziuej December~ 186-1.
Sin'--The enormous outlay which attends the opening and working of mines in districts where the strata are, as in Cornwall, of an exceedingly hard nature, is due mainly to the slow progress which can be made in sinking shafts, or driving levels or headings through such refractory rocks. Thus £ 60 per fathom is not an unusual price for sinking a shaft in hard Cornish stone ; and even at this immense cost the progress made is very small. Iu solid limestone rock a shaft 9 feet in diameter can be sunk for .£ 7 per fathom, and at the rate of ten fathoms per month ; but a shaft in hard capal or roskear stone costs 2~ 60 per fathom, and perhaps not one fathom per month can be sunk. In each case, the labor is mainly accomplished by boring holes ia the rock, and firing them with charges of powder, the explosion of which bursts, and breaks up the rock. :Now in limestone these holes can be rapidly bored, because limestone is considerably softer than good hardened steel, and therefore the steel borer keeps its edge a long time, and cuts the rock keenly and quickly. But eapal or roskear stone is nearly and often quite as hard as the best hardened cast steel ; hence the edge of the borer is soon worn or beaten up, and in place of cutting the stone keenly, it merely bruises it away by degrees, making slow progress through it, and to enable even this to be done, the edge of the borer bit has to be made very thick and obtuse, and in a form the least calculated to penetrate rapidly. In boring a hole 8 inches in hard veinstone, upwards of 200 borer bits have had to be re-set by the smith, and the cost of each re-setting or tempering is fairly stated at about threepence for each bit, taking labor, loss of time, &c., &e., into consideration. Now, if a steel can be produced which, when hardened, will be as much harder than eapal or roskear stone as the best hardened steel at present made is harder than limestone, then by the aid of this steel shafts may be sunk and levels driven in the hardest ground as rapidly and as economically as can at present be effected into ordinary limestone rock. Such a steel can be produced, and I invite the attention of mining