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On polishing metals
0~ Polishing Metals..
~65
plaster stone, in the large way, with regularlty~ and thus constantly obtain this plastic material of the best quality.. In fact, as thewhole question of baking the plaster is now reduced to a simple desiccation, easily cffected by steam, so all the difficulties hitherto experienced, fi'om the bad construction of the furnaces, whether heated by wood, pit coal, or turf, may be made to disappear. We can also thus usefully employ the enormous quantities of plaster stone in powder,, which now,imcumbers the ~luarries; as it would be proper, hencelorth, either to crush the stone into small frazments, or, still better, to gvimt it to a coarse powder in mills, bet~ore baking it. This tirst labour wnuhl not be lost, as the baked plaster might be sit'ted, and directly employed without beitlg subjected to pounding or beating, au expensive operation, and which always causes the toss of a great quantity of the material. A perfect regularity in heating the plaster stone may be attained by means of sleam; Using an inclined plane, formed of cast troll tubes, flattened at top, and communicating with each other at their ends. This steam tube is to be comlected with an ordinary high pressure steam boiler, and so disposed that the condensed water may return again into the. boiler. A manometer. . (or steata ~*,au,~e~.) must be placed ~u mm ol the tubes to indicate the pressure of the steam, and to r%ulate the temperature accordingly. A pipe with a stop cock must be t~laced on one of the most elevated parts of the tubes, in order to permit that air to escape which might oppose the constant communication of the steam. We could also employ a set of cast iron plates, which might be covered with plaster stone to be baked npou the steam tubes, and be removed when that operation has been performed, and replaced by others in constant succession. Whatever has been the mode of baking adopted, we must carefully prevent the plaster fi'om being exposed tbr a long time to the at?9 and especially when it is moist~ as-it would absorb the water again by degrees, and thus become incapable of hardening when we would employ it~ and, in fact, will have become an inert po~der, ro use this plaster, we have only to add to the p0:wdei~asuflleient quantity of water, when it will directly assume "thg:eonsistenceof ordinary mortar, and must be mixed ut~ wittVa'tt0wd~, ~ The fine plaster, mixed with a solutl0n, 0fgliiei ;and~liaving after;wards various hard and coloured substances ine0rP0rated with it, :forms the basis of one of the processes emp!oyed:iii the making of :stucco, to imitate marble. Plaster is als0 emi~loyed ih buildings, and in moulding objects of sculpture: it sei¢~/es:io decompose the ammonia, in the manufiacture of sal ammoniae~ and great use is made P. of gypsum in agriculture. [Tech, Rep.
On Polishing ~letals. [From the 1)ictionnaireTechnologlque.] B~.roaE proceeding to polish metal%~they com~ a e n c e , b)t, )relJarin~,~, the surfaces they wouhl polish; that is to say, it is of importance to VoL. VI.~No~ 4.--Oc:roB~:r~, 18:30, 54
~o66
On Polishing ~[eta&.
remove atl tile marks left by fl~e file, the turning tool~ tile scraper} &c. in order to render the surfaces uniform. This preparation is .effected on, those metals, which are not very hard, by means of pumice stone, either used m substance or reduced to powder, and water; when in powder, it is applied Ul)Onfelt, Or: upon slips of soft wood, covered with buffalo or chamois skin~ it:the surfaces be flat; or with pieces of soft wood, properly shaped, so as to penetrate into the hollows, and act upon the raised parts. When the first course marks are thus removed~ they then proceed to remove those left by the pumice stone. In order to this, the)' employ finely powdered pumice stone, which they grind up wit~ olive oil, and employ it upon felt~ or upon small pieces of Soft wood~ such as that of the willow or sallow. It is necessary, in these mani, pulations, to observe an important rule, which is never to proceed from one operation to another~ before previously washing the pieces of work well with soap and water, by means of a brush, in order t~ remove the pumice stone~ using.~water entirely, before employ: lug oil: and likewise never to use those to~ls t'or succeeding operations, which had been used in preceding ones; each staee o'~ the operation requiring particular tools; and which should be~kept in closed boxes, in order to prevent the powders ti'om being diffused~ or scattered about, when not in use. Without taking these pretau. tions, which must be particularly and minutely attended to, we shouht be liable to make fresh scratches instead of removing them. After removing the marks left by the coarse pumice stone and water, by means of finely ground pumice stone and oil, we should wash it with soap and water, and dry it well with a wifite linen cloth: we must then examine it with a lens, or a magnifying glass, to see whether any scratches yet remain; if not~ we may proceed to th~ polishing. The softer metals are polished in different manners, accordingt0 their size and their uses; the larger gold works are, howeve5 genie: rally burtfished; but the smaller ~ohl works in iewellery,:~c., and those i,~ bra.~s for watch work~are not bnrnished~ but p6iislied; Tile following are the n~anipulatiolas. After having removed with of[ stone powder, the marks of ~he file., &c. they smoothen them with blue and gray stones, and plenty of water: there are two kinds of these stones, the one soft, and the o~her hard; the first is designated: by Brongniart, under the name of ar~illacebus schistus, and is the kind in question: the second kind is ~amed by the above mineralo: g st, sdnste cohcule; th~s serves to sharpen tools upon. /he p~eees of watch work are always smoothed i'n this manner, until all the marks disappear, and which is known by washing them in the ~nannet above mentioned with soap and water. They finatly proceed to the oolishin~ by emolovln~ the tripoli from: Venice, which is most to be I)referred,'anO(1 is'eittqer~nel'~ ~roundi:~: water, or in olive oil, accord'the to the different eases, fi')r~piecesof gold work, or the !arger kinds'of jewelIery articles, and until tl,~~ percetve their surfaces are become perfectly brilliant: they t
Jlntiquit9 o f the a r t o f l~a1~'~Ma~'ng.
~
finish them with tripoli, reduced plied upon a very soft brush. For polishing those pieces of ~ after smoothing them with the polish them with rotten stone, ~v very fine, ground up with olive oi This rotten stone is, according light tripoli, but finer and more comes from England, and is highly esteemed for polishi'ng with~ it is of an ashy gray tint, and is lbund in thin layers, upon the compact carbonate of h'me, near Bakewell, in Derbyshire. Tile polishing of steel is not executed in tile same manner as in polishing the s(~fter metals: the steel is not polished until it has been hardened, and the harder it is the more brilliant is its polish. The substances we have above indicated for polishing other metals are not powerful enough to attack a substance so hard as this. W e must employ emery, a substance so well known, as not to need describing here; it is used after having been ground in oil. The hardened steel is either polished fiat, like glass, or cut into facets like a diamond, and, consequently, the lapidary's mill is used. They commence, by smoothing the wm-k with emery rather coarse, then with finer emery, and finish with tim finest. Tbe smoothening being perfectly etti~cted, they polish it with English rouge (tritoxide of iron) and oil, and, finally, finish it with the putty of tin (peroxide of tin) and water; but if upon mills or laps of zinc, then without the use of water. Whep the steel articles consist of raised attd hollow work, they are smoothed and polished With~the same substances; but the instruments are, as in the case of the less hard metals, pieces of wood, properly shaped, and employed in the same manner. I.
IT has beengeneritlly conceived that the first.rudlmentS 6f the,art of making paper, according to the process no~ in use, wer~acquired by the Arabians from certain Bukharian manufacturers; about thV year 704, and by them introduced into Spain, in the eleventh i~entory. ~Ve are, however, about to draw the readePs attention to a ecork which throws an entirely new light on the subject, and goes rat to establish a remoter date. The conjectures of former investigators have been derived exclusively from a consideration of the ma!erials employed by the ancients; hut ourlearned fi'iend, Musumeci, Lnhis recent essay " on the ancient use of various kinds of paper, md the art of making it,"* has taken up the subject on the only ,~rounds from which clear and positive inferences can be drawn; he ~as inquired into the mechanical means by which those materials were produced, and instituted a " comparison of the process for Catania, ~{vo,1829.
~65
plaster stone, in the large way, with regularlty~ and thus constantly obtain this plastic material of the best quality.. In fact, as thewhole question of baking the plaster is now reduced to a simple desiccation, easily cffected by steam, so all the difficulties hitherto experienced, fi'om the bad construction of the furnaces, whether heated by wood, pit coal, or turf, may be made to disappear. We can also thus usefully employ the enormous quantities of plaster stone in powder,, which now,imcumbers the ~luarries; as it would be proper, hencelorth, either to crush the stone into small frazments, or, still better, to gvimt it to a coarse powder in mills, bet~ore baking it. This tirst labour wnuhl not be lost, as the baked plaster might be sit'ted, and directly employed without beitlg subjected to pounding or beating, au expensive operation, and which always causes the toss of a great quantity of the material. A perfect regularity in heating the plaster stone may be attained by means of sleam; Using an inclined plane, formed of cast troll tubes, flattened at top, and communicating with each other at their ends. This steam tube is to be comlected with an ordinary high pressure steam boiler, and so disposed that the condensed water may return again into the. boiler. A manometer. . (or steata ~*,au,~e~.) must be placed ~u mm ol the tubes to indicate the pressure of the steam, and to r%ulate the temperature accordingly. A pipe with a stop cock must be t~laced on one of the most elevated parts of the tubes, in order to permit that air to escape which might oppose the constant communication of the steam. We could also employ a set of cast iron plates, which might be covered with plaster stone to be baked npou the steam tubes, and be removed when that operation has been performed, and replaced by others in constant succession. Whatever has been the mode of baking adopted, we must carefully prevent the plaster fi'om being exposed tbr a long time to the at?9 and especially when it is moist~ as-it would absorb the water again by degrees, and thus become incapable of hardening when we would employ it~ and, in fact, will have become an inert po~der, ro use this plaster, we have only to add to the p0:wdei~asuflleient quantity of water, when it will directly assume "thg:eonsistenceof ordinary mortar, and must be mixed ut~ wittVa'tt0wd~, ~ The fine plaster, mixed with a solutl0n, 0fgliiei ;and~liaving after;wards various hard and coloured substances ine0rP0rated with it, :forms the basis of one of the processes emp!oyed:iii the making of :stucco, to imitate marble. Plaster is als0 emi~loyed ih buildings, and in moulding objects of sculpture: it sei¢~/es:io decompose the ammonia, in the manufiacture of sal ammoniae~ and great use is made P. of gypsum in agriculture. [Tech, Rep.
On Polishing ~letals. [From the 1)ictionnaireTechnologlque.] B~.roaE proceeding to polish metal%~they com~ a e n c e , b)t, )relJarin~,~, the surfaces they wouhl polish; that is to say, it is of importance to VoL. VI.~No~ 4.--Oc:roB~:r~, 18:30, 54
~o66
On Polishing ~[eta&.
remove atl tile marks left by fl~e file, the turning tool~ tile scraper} &c. in order to render the surfaces uniform. This preparation is .effected on, those metals, which are not very hard, by means of pumice stone, either used m substance or reduced to powder, and water; when in powder, it is applied Ul)Onfelt, Or: upon slips of soft wood, covered with buffalo or chamois skin~ it:the surfaces be flat; or with pieces of soft wood, properly shaped, so as to penetrate into the hollows, and act upon the raised parts. When the first course marks are thus removed~ they then proceed to remove those left by the pumice stone. In order to this, the)' employ finely powdered pumice stone, which they grind up wit~ olive oil, and employ it upon felt~ or upon small pieces of Soft wood~ such as that of the willow or sallow. It is necessary, in these mani, pulations, to observe an important rule, which is never to proceed from one operation to another~ before previously washing the pieces of work well with soap and water, by means of a brush, in order t~ remove the pumice stone~ using.~water entirely, before employ: lug oil: and likewise never to use those to~ls t'or succeeding operations, which had been used in preceding ones; each staee o'~ the operation requiring particular tools; and which should be~kept in closed boxes, in order to prevent the powders ti'om being diffused~ or scattered about, when not in use. Without taking these pretau. tions, which must be particularly and minutely attended to, we shouht be liable to make fresh scratches instead of removing them. After removing the marks left by the coarse pumice stone and water, by means of finely ground pumice stone and oil, we should wash it with soap and water, and dry it well with a wifite linen cloth: we must then examine it with a lens, or a magnifying glass, to see whether any scratches yet remain; if not~ we may proceed to th~ polishing. The softer metals are polished in different manners, accordingt0 their size and their uses; the larger gold works are, howeve5 genie: rally burtfished; but the smaller ~ohl works in iewellery,:~c., and those i,~ bra.~s for watch work~are not bnrnished~ but p6iislied; Tile following are the n~anipulatiolas. After having removed with of[ stone powder, the marks of ~he file., &c. they smoothen them with blue and gray stones, and plenty of water: there are two kinds of these stones, the one soft, and the o~her hard; the first is designated: by Brongniart, under the name of ar~illacebus schistus, and is the kind in question: the second kind is ~amed by the above mineralo: g st, sdnste cohcule; th~s serves to sharpen tools upon. /he p~eees of watch work are always smoothed i'n this manner, until all the marks disappear, and which is known by washing them in the ~nannet above mentioned with soap and water. They finatly proceed to the oolishin~ by emolovln~ the tripoli from: Venice, which is most to be I)referred,'anO(1 is'eittqer~nel'~ ~roundi:~: water, or in olive oil, accord'the to the different eases, fi')r~piecesof gold work, or the !arger kinds'of jewelIery articles, and until tl,~~ percetve their surfaces are become perfectly brilliant: they t
Jlntiquit9 o f the a r t o f l~a1~'~Ma~'ng.
~
finish them with tripoli, reduced plied upon a very soft brush. For polishing those pieces of ~ after smoothing them with the polish them with rotten stone, ~v very fine, ground up with olive oi This rotten stone is, according light tripoli, but finer and more comes from England, and is highly esteemed for polishi'ng with~ it is of an ashy gray tint, and is lbund in thin layers, upon the compact carbonate of h'me, near Bakewell, in Derbyshire. Tile polishing of steel is not executed in tile same manner as in polishing the s(~fter metals: the steel is not polished until it has been hardened, and the harder it is the more brilliant is its polish. The substances we have above indicated for polishing other metals are not powerful enough to attack a substance so hard as this. W e must employ emery, a substance so well known, as not to need describing here; it is used after having been ground in oil. The hardened steel is either polished fiat, like glass, or cut into facets like a diamond, and, consequently, the lapidary's mill is used. They commence, by smoothing the wm-k with emery rather coarse, then with finer emery, and finish with tim finest. Tbe smoothening being perfectly etti~cted, they polish it with English rouge (tritoxide of iron) and oil, and, finally, finish it with the putty of tin (peroxide of tin) and water; but if upon mills or laps of zinc, then without the use of water. Whep the steel articles consist of raised attd hollow work, they are smoothed and polished With~the same substances; but the instruments are, as in the case of the less hard metals, pieces of wood, properly shaped, and employed in the same manner. I.
IT has beengeneritlly conceived that the first.rudlmentS 6f the,art of making paper, according to the process no~ in use, wer~acquired by the Arabians from certain Bukharian manufacturers; about thV year 704, and by them introduced into Spain, in the eleventh i~entory. ~Ve are, however, about to draw the readePs attention to a ecork which throws an entirely new light on the subject, and goes rat to establish a remoter date. The conjectures of former investigators have been derived exclusively from a consideration of the ma!erials employed by the ancients; hut ourlearned fi'iend, Musumeci, Lnhis recent essay " on the ancient use of various kinds of paper, md the art of making it,"* has taken up the subject on the only ,~rounds from which clear and positive inferences can be drawn; he ~as inquired into the mechanical means by which those materials were produced, and instituted a " comparison of the process for Catania, ~{vo,1829.