On various cements

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'I'HE rnAxr~zrAN JO~Rh'AL AND

Oh" VARIOUS C E M E N T S . - - B Y Zllo3iAS GILL,

l~ttcs's 14"ater.Proqf Glue 07" Cement. Take of the best ]ri~h glu% fimr ounces ; and of isinglass, two fa~:~c~,s : t~ese must be dissolved in mild ale (not stale,) over a slow ti,-e, ia ~ common glue-kettle, to the consistence of strong glue; ~vJ~en one o~,r~ce and a half of well-boiled linseed oil must be gradually added, and the whole well incorporated together by stirrb:g. To iz~cr(~c the strength of the glue, rnove isinglass may b~ addod. This ecmer~t is applicable to tim joints of wood, in every branck of man~Aiteture ; as also to joining earthenware, citing and g l a s s ~ care bein~ iakeJ~ to press the parts well together, and to allow them sufficient time to set. The ce:net~t, when cold, and made into cakes, assumes the appearance nf India-rubber; and like it, is eiastlc. It may at any time, when wanted for use, be dissolved, by a gentle heat, in any proper iron or glazed earthen-vessel ; first putting into it a little mild ale, to prevent it fi'om burning at the bottom ~f the vessel ; a~M addirt:z move ale, to bring it to a prm)er consiste.,me for nee. '1"(, cement tealher together, fi)r harness, b~ands fi)r machinery, &e, havi,'~g prepared the joints in the usual way, as if for sewing, apply ti~e cenle~(: while hot, layi,~g a weight upon each joint, as it is nmde : tt't t!~em remain six hours before uaing, and the joints will "lben b,,,e(mm nearly as firm as if made of one entire piece of leather. Al~ exceAlent cmnent for stopping leaks in casks. &c. may be made b? l)uttlf~g a little tow to the other ingredients. '

Glue and Rosin Ceme~t. Two p~rts of alt.,e and one part of rosin are to be incited together; Gild a sufficient quantity of red-ochre added, to c~lvur it. This c~w,~cnt is used to cement hones into their wooden-fi'ames, and al~t)eavs likely to be useful for many other purposes.

Glue rind Zi~seed-Oil Cement. S~"on~ glue, well inr, h~ wilh water, one pint; and one-eighth of a ?in! ~t" ii~,se,.,d oil added to it, drop by drop, whilst boiling.. V~itii this {ztue or ceme~t, the joiners unite the parts of s~gnboa:'ds~ o~' o[.hcr ~,w)tks wtfich are to resist the effects of moisture.

0:~ tT~e Gum-,~m'moniaeal Cement. This ceme~tt is fi)rmed by adding to a solution of gum-armnortiae in proof-sI@i t, some isinglass or parchment-glue, and uniting them in a gentle heat, The chief vaIoo of this cement consists in the ,n'eat: readi~ess with which it melts in a small degree of heat, andethe little tendency it has to be atI~cted by moi~tureo This cement is very much employed by entomologists, in joining' together tl~e dish,rated parts of insects ; for which purpose it is exceedingly conve~ lent.

A ~ n l C A r ~ MECHAmCS~ MAGAZINE.

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Isinglass Cement. ~+=~ Isinglass, dissolved in brandy or proof-spirit, r e a d ~ i ~ : m ~ l , , a gentle heat, and fi~rms a very useful and convenient c e m e n t . Cement of Isinglass and Gum-a~rabic. This cement is composed of two parts of isinglass, and o n e t ~ v t . of the best gum-arabic, put into a bottle, and covered with gin o r proof-splrlt ; and the bottle being loosely corked, is to be p l a c e d in a vessel of water, and boiled till the splutlon is effeeted ; w h i c h may the~l be strained for use. In this valuable cement, the isinglass and gum-arabic c o r r e c t e a c h other's defects ; the isinglass giving to the gum toughness, a n d tht~ gum inc,'easing the hardness of the isinglass; and both t o ~ e t h e r forming a most useful cement, particularly for mouuting dpa~iu ~ objects for the microscope.

On, the use of TVafers~ as an extempo~'aneous Cement. A great hnprovement in the manner of using wafers, so as t o cause them to unite or hold papers together more firmly arid n e a t ly, is to divide or split them with a pen-knife, and thus to f o r m two wafers out of one, of only half tile usual thickuess. T h e s e may be cut into small pieces, and applied by first wetting th~ p a per in the places, to be. cemented,, and laying a piece of w a f e r - o n each ; and then wetting the pieces of wafer, over which the o t h e r paper to be united may be placed, and pressed close : thus p e r f e c t ly effectiug the union. A very cheap cement is thus r e a d i l y o b tained ; and with white wafers, owing to the thinness of the s p l i t wafer, no marks will be seen, as is the case where the entire w a f e r is used: the union also is so perfect~ as to render s e p a r a t i o n i m possible, as is sometimes effected by splitting the entire w a f e r .

Improved Gum- Water. I t is well known that tile mucilage of gum-arabic is exeeedin~.ly liable to become spoilt by keeping. If, however, the gum be d i s solved in water, and made of a thick consistence, and a h t t l e ale hol added to it, that evil will be prevented ; or the solution m a y be made at once, in ~in or other nroof-spirit. This gum-water should be kel)t'in a wide-mouthed glass v e s s e l , with a ground stopper, to prevent the escape of the alcohol. A n d although it has not the strength o f the above described c e m e a t j which is composed of gum-arabic and isinglass, yet it is v e r y s e r viceable for many purposes, especially as it does not require to be heated befbre using. ¢, o f s m a l l A very convenient way of applying it to the ~mentin~, .~ labels on specimens of minerals, &c, is, by forming an i n s t r u m e n t ot a small common pin, stuck a little way iiJto a slender poil~ted halo_* A g'ooclcork is much better, as the stopper will baeome firmly aemaxttad~ ---EDrroa. Vet., I,--No, 9~.~F~Bnw~r: 18~. 15

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die of wood : tile head of the pin, on being dipped into the gun~.~ water, takes up a sufficient quantity at a time : and it may then, be applied, in a small spot, to each end of the label, whicli is generally sufficient to secure it to the specimen. On Shell-lae, as a Cement.

Thla article is largely employed by the hair-workers in jewellery, to cement the hair into the toilets, and thus to orm it into bracelets, &c. rhe mode of using it is as follows : - - T h e shell-lae is put into a basin, and the basin placed in a Dutch-oven, which is set before an open fire, until the shelt-tac becomes melted by the effects of the gentle heat t.hus applied:, and can be drawn out into slender threads or rods fft to'enter tile small eollets. To use it, the coHets must be warmed suffr.ciently to melt the sheH-lac, but not more; as its utility greatly depends upon the volatile parts being preserved, which at,e quickly dissipated by to(~ great heat. The hair is then to be placed within the collets, and thus secured'wi~lr shell-.tacl tile ruby cylinders of watches~are In firmly like manner, firmly cemented in their sockets, by the watch-jewellers. 01~ Copal, ~mber, or Gum-Mastleh, as extemporaneous Cements,

These substances may be employed in tlieir natural state, much in tile same way as tlie shell-Is% tbr,ning exceedingly hard and durable cements. Tile jewellers use tlie last-menti0ned article in uniting the two stones which form tlieir doublets; although it would seem that copal would much better answer tbat purpose, from its greater hardness. Amber, also, wl~erc its colour is no objection, is yet fitter than either to efi~ct this object, on account of its stil!~ greater strength. O~z Glue, as an extemporaneous Cement.

This article, sawn into slip% is of great use to artists, in ce.raenti}~g paper, vellum, &c. to their drawing boards~in the follownl~ manner. The paper, &c. being damped upon its back, b~" means of a wetted sponge, and laid upon the drawing-b0ard, tiae end of the slip of glue is to be dipped into hot water, and rubbed between the edges of the paper and the drawing.board, so as to apply a slight coat of stiffglue to both: the paper is then to be rubbed down hard ul)on tile board, until the union is effected ; and, in case of the paper becomil~g loosened in places by its stretching and tightening. as the water evaporates, tile same process is to be repeated. %¥hen the drawing is completed, the paper, vellum, &c. may be readily taken oil' the board, by inserting an ivory folding-knife be: tween it and the board. And what little still remains adhering t<~ ~he board, may be removed, previously to cementi,g another pape c ~Ypoa i,t, with a sponge and ]tot water.

~MER~CA~ MEChANIcs' ~ Z I ~ E .

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Varley's Cement. Take sixteen parts, by weight, of black rosin, thews/Linequantity of whiting, and one thirty-second part of bees-wa~::, The whiting finely powdered, must be previously heated redhot, to expel all moisture ; and be suffered to "¢ool, before adding it to the melted rosin and bees-w.ax. This cement is exceedingly useful in the various mechanical arts, and particularly in turning in general, for tile purpose of cementing articles to chucks, &e. in the lathe. It is also used in watchjewellery, to hold the ruble% &c. fast, in turning and drilling them in the lathe : for this purpose, however, Mr. Seymour, formerly a ~vorkman of Mr. Varley's,.thinks that chalk in its natural state, finely powdered, is preferable .to the washed cbalk or whiting; and he also varies the proportion of the bees-wax, according to the warmth or coldness of the weather. It will be seen that the :rosin farms the chief binding ingredient in this cement~ the bees-wax being added merely to give i.t toughGlue from Tanned Leather. -:Itis generally thought that the process of tanning, renders leather exceedingly insoluble. Means, however, have :been found to overcome that insolubility, and to form a glue exceedingly well adapted to tile purpose for which it has hitherto been u:sed ; namely, that of making the black paper cases, so much used for a great variety of purposes; as it not only forms the cement ~by which they are glued together, but also, in consequence of the gal4ic:acid contained in it, strikes a black colour, by the al)pl,icafion .of a solution of sulphate of iron (green ~¢itrial, or copper, e-s) to the surfaces of the ar!icles ; and lastly, serves to varnish the i~ases. l'he process for making this glue is as follows :-.Boil the scraps or cuttings of thin tanned leather ; such as the u:pper leathers of boots, shoes, &c. are made of, in stale urine, until they become softened, and will stretch and contract, when pulled and let go again, in the manner of India.rubber: they are then to be washe(l in el.can water, a~d boiled in water until dissolved to a proper cons,stence for use. It is very singu'lar that this useful process has been hitherto confined to the above branch of manufacture ; and has never, to the best of the EditoPs 'knowledge, been before published. On the ~'ench Glue from Bones. ~ This is made at Paris, by M. Robert, in ,the following manner: The bones used, are those only which, previous to this discovery, a~swered no useful purpose except for the fabrication of phospho: rus, ammonia~ animal charcoal, bone-ashes, or manure ; such, for in=

* Extra~ted~ with alterations, from Silllman%Journal of Science and th~

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stance, as those of the head, ribs, &c. ']['he refuse of the legs of sheep and calves, &c. which had been already partly used for the purposes of the toy-men, (tabletiers) are also used for tiffs purpose, after extracting as much of tim gelatine and fat as can be done by ebullition. When the heads of oxen are to be oper'ated upon, they begin by extracting the teeth, (these being reserved fiw the fabrication of ammonia, as affording a greater proportion of that alkali than any of the other bones:) they then break the skull, in such a manner a~ to preserve all the compact parts in as regular forms as possible ; these pieces present a surtace of from twenty to thirty inches square, and are put to soak in a mixture of muriatic acid and ware,-. The muriatic acid used, marks about ~23° of the areo. meter, and is diluted by water to about 6 °. Four parts of the liquor is used to one part of the bones. They are left in this state, in open vessels, until a complete solution of the phosphate of lime '.,~ an d th,e ge I*atmous " has taken p,~.~e, p,art o f the bone. remains in its," original shape and size, and is perfertly supple. When this operation is finished; which commonly lasts six or eight days, the gelatine is pul illt:) baskets, being tirst drained ; and is immersed a short time in bt)iling water, in order to extract any sinai] remains of grease, which would deteriorate the gelatine ; and also to extract any of the acid which might be lodged in the pores. It is then carefully wiped with cleat~ linen, and-afterwards washed in copious streams of cold water, to whiten it, artd render it more tra~spare~t : it is then put to dry in the shade. This is used for making glue of a very superior quality. ¢ ~" ' " ': ' Ille ~nstde ot the bones of sheeps 3 legs, furnish a sort of membranous ~'lue, w!ficb supplies with advantage, the place of isinglass, in the fabricatiou of silk stuffs*

Remarks on th~s Process. Glue is generally made in this country , as is well known, from the skins of animals. The Editor would, however, wish particu* larly to call the attention of persons to the great superiority, in point of strength, of the glue made from bones, over the best Euglish 7,1ue ; as appeared fi'om various trials made with it by a skilful English workmau at P~ris, in comparison with that of the best lglue tnade ir~ England ; and on the result of whose experiments he ms every reason' to place absolute confidence. It surely is highly necessary that e~)deavours should be made in this country, with a view of re-establishing the preference hitherto shown to the English glue: ~nd, hldeed, there has lately been a Patent taken out for a new method of manufacturing glue from bones, by means of steam.

On the Trocesses of T~mnlng,, Zeather-Dresslng, and Dying, ~'e. j?om ~qikin's Dictionary of Chymistry. The preparatiou of the skins of animals for the many important purposes to which they are applied, is, almost exclusively~ in ali its branches, a chymical process.