jotting, (Enamelling, an& <£lass ^taming. THE VALUABLE RECEIPTS OF THE LATE MR. THOMAS LAKIN, WITH PROPER AND NECESSARY DIRECTIONS THEIR PREPARATION AND USE IN THE MANUFACTURE OF PORCELAIN EARTHENWARE. AND 3£ron Jrtone Cljtna, TOGETHER WITH THE MOST RECENT AND VALUABLE IMPROVEMENTS IN THE ADMIRED ART OF GLASS STAINING AND PAINTING. LEEDS: PRINTED FOR MRS. LAKIN, BY EDWARD BAINES, 1824. INDEX. PAG S Section I. Receipts for superior and common Bodies of Porcelain, Earthen- ware, vitrious and porous Bodies, with various coloured Drabs 1 Section II. Receipts for superior and common Glazes of Porcelain, Iron Stone, Earthenware, and various coloured Drabs 19 Section III. Receipts for Enamel Colours, and Colours under Glaze, burnished Gold, and Lustres ; printed Blue, Brown, and Mulberry, with various Fluxes, Solutions, and Oxides 33 Section IV. Receipts for preparing Zaffre and Cobalt Blue, with the Pro- cesses of Smelting, Refining, and Calcining.,. 65 Section V. Introduction to Painting and Staining Glass 73 Receipts for Stains and Enamel Colours for Painting Glass, with the Process of Etching and Coating Glass 76 PREFACE. The progressive improvements in the manufacture of Por- celain and Earthenware, during the last thirty years, have raised this art to an eminence which it never reached before in the British Empire ; and, perhaps, in no department of art has scientific research and experiment been so productive of wealth and fame as in this, and it is no undue encomium on the industry of the manufacturer to state, that the consumption at home, and the demands from abroad have kept pace with the improvements which have increased both. The important station which this art holds amongst our manufactures, renders every attempt at improvement worthy of consideration and attention. It has been said, the man who causes one ear of corn to grow where one never grew before, deserves the thanks of his country ; but what does that man merit who, by indefatigable industry, contri- butes materially to the advancement of the interests of his country, in the improvement of its manufactures; it was in this class, that the late Mr. Thomas Lakin held a situation VI much above mediocrity, for, in Staffordshire, it is well known that few men have contributed more to the improvement of an art so useful and so much admired. The following work is the result of upwards of thirty years oflabour, study, and repeated experiment, and no pains have been spared in arranging the various Receipts in such a chain of connexion as to render them easy of comprehension to an intelligent operator. The Subscribers may rest assured, that the whole of the following Receipts may be individually depended upon as genuine, each having been repeatedly tried in the course of the Author’s long experience. Mr. Lakin had also ex- tensive practice in the admired art of Staining and Painting Glass ; several windows of exquisite workmanship were ex- ecuted by him during the time he was egaged with John Davenport, Esq, for some of the first noblemen in the king- dom. The Receipts, together with the method of using them, are therefore laid down from actual experiment, and it is hoped will be found extremely valuable. In presenting the following work to the Subscribers, Mrs. Lakin is anxious to express her gratitude for the liberal encouragement she has met with, and for the highly gratifying tribute they have paid to the abilities of her departed hus- band ; but to the kindness of those gentlemen who had before Vll purchased some of the Receipts at a price far beyond the whole charge of this work, and yet have become subscribers, she feels herself particularly indebted. Mrs. L. respectfully solicits of the Subscribers not to permit persons who are not purchasers to copy any of the Receipts, as it might not only injure her as proprietor of the copy-right, but also other subscribers ; on her part she pledges herself not to publish the work, nor permit the work to be published, at a lower price than that at which it is now offered to the Subscribers. ^ - 7^'. S • O Digitized by the Internet Archive in 2016 https://archive.org/details/valuablereceiptsOOIaki A GENERAL SYSTEM OF POTTING, ENAMELLING, GLASS STAINING, SECTION I. RECEIPTS for superior and common Bodies of Porcelain, Earthenware, Vitreous, and Porous Bodies, with various Coloured Drabs. * PROCESS 1. To make a superior Porcelain Body. Take 360 Parts of Bones. 230 - - of Cornish Clay. 50 - - of Cornish Stone. 20 - - of Flint. 20 - - of Blue or Brown Clay. 10 - - of Frit. See Process 30. jr - - of Blue Calx. 2 PROCESS 2 . To make a superior Porcelain Body. Take 400 Parts of Bones. 360 - - of Cornish Clay. 250 - - of Cornish Stone. 20 - - of Flint. j - - of Blue Calx. In the bones used for the purpose of making China Bo- dies, every attention should be paid, that no decayed ones are made use of. The bones of animals owe their great firmness and solidity, to a considerable portion of phosphoric salt of lime which they contain ; when broken into small pieces and boiled in water, they afford gelatinous matter, with a portion of fat oil ; but by destructive distillation, they produce much volatile alkali. Bones are inflammable by virtue of their oil, and emit an offensive empyreumated smell ; the white friable residue consists chiefly of lime in combination with phos- phoric acid. The qualities of China clays differ very much, being al- ways mixed with particles of talc and mica. Mr. Wedgewood, in analizing, found them to contain 60 per cent, of argil, and 20 of silex ; consequently, they are infusible at the most intense heat. These clays are of a yellowish white colour, smooth and greasy to the touch ; with regard to the other ma- terials used in the manufacturing of Porcelain, proper care and attention should be strictly observed, that the purest kinds be made use of, otherwise it is probable the attainment of the object that the operator has in view, will be completely frus- trated ; it will be found on examination, or by experiment, that materials differ considerably as to quality. These porce- lain bodies fire at a higher temperature than those gene- rally manufactured in this country, and commonly are placed and fixed with ground flint previously calcined ; being thus bedded in flint, each piece will retain its proper and regular shape. The mixture after being well dissolved in the water, is called slip, and is then sifted of a thickish consistence through the finest silk lawn, till it acquires the requisite degree of fineness ; if sifted too thin, it will contain too much water, and the imperfect parts of the materials will be found to have passed through the lawn ; under such circumstances, the slip will be much reduced in its specific gravity, consequently the body will be found inferior ; and as china may be justly con- sidered the master-piece of the potter’s art, it will be highly essential to examine the materials of which the clay is made, in order that it may be brought to the highest state of perfec- tion of which it is capable. 4 PROCESS 3. To make an Iron Stone Body. Take 300 Parts of Cornish Stone. 250 - - of Cornish Clay. 200 - - of Blue or Brown Clay. 100 - - of Flint. 1 - - of Blue Calx. PROCESS 4. To make an Iron Stone Body. Take 175 Parts of Cornish Stone. 150 - - of Cornish Clay. 90 - - of Blue or Brown Clay. 35 - - of Flint. 5 - - of Frit, see Process 30. i - - of Blue Calx. These Bodies are very ductile, and fire at the temperature of the common biscuit oven ; each piece of ware should be perfectly dry when placed in the Seggars, because they are made a great deal thicker than any other kind. Setters also should be used at the bottom of each piece, and ground flint applied, but not sand, for the placing or seating ; the Body, when burnt, is quite vitrified, and the pieces of ware strong and heavy, ringing remarkably shrill. o PROCESS 5. To make a superior Printed Earthenware Body. Take 3 Parts of Blue Clay. 1 - - of Black or Brown Clay. o of Cornish Clay. H - - of Flint. z 4 - - of Cornish Stone. - - ' PROCESS 6. To make a Common Printed Earthenware Body Take 2 Parts of Blue Clay. o •*0 - - of Brown or Black Clay. 1 - - of Cornish Clay. H - - of Flint. PROCESS 7. To make a Superior Cream Coloured Body. Take 1^ Parts of Blue Clay. H - - of Brown Clay. i - - of Black Clay. l - - of Cornish Clay. l - - of Flint. i 4- - - of Cornish Stone. 6 PROCESS 8. To make a Common Cream Coloured Body. Take 1^ Parts of Blue Clay. 1^ - - of Brown Clay. 1^ - - of Black Clay. 1 - - of Flint. In superior and common Bodies of printed and cream colour, the mode of preparation is the following : — The com- mon clays are distinguished by colour and name ; the Blue, Black, and Brown are most generally used ; these are put into a large vessel of water, called the soaking tub or pot, and after being well stirred about, the clays quickly dissolve, and the water becomes of the consistence of slip, which is then passed through the finest silk lawn into another vessel, with proper gages fixed therein, so that the other materials may be cor- rectly added afterwards in a slop state ; the clay slip weighing per gallon 13^ lbs. Cornish Clay 13^ lbs. Cornish Stone lfii lbs. Flint 16^ lbs. and the passing through the lawns re- peated again, as often as needful, so that the mixture may be deprived of all impurities. It is, perhaps, almost unnecessary to observe again, that it behoves every manufacturer to be very particular in ascertaining the quality of the different materials previous to using ; some clays holding so much iron in solution as constitute them little better than marl, others are impreg- nated with pyrites in such proportion that when burnt exhibit abundance of metallic specks. 7 PROCESS 9. To make a fine Lilac Porcelain Body. Take 200 Parts of Bones. 115 - - of Cornish Clay. 25 -- of Blue Clay. 20 -- of Flint. 15 - - of Cauk Stone. 10 -- of Cornish Stone. u - of Blue Calx. This process requires a fire of the same temperature as the Porcelain Bodies, and must be treated in every respect exactly the same in manufacturing, - - of Blue Calx. For these blue enamels the materials must be calcined in an air furnace or glazing oven, and caution should be observed that they are not too finely ground at the mill, in order to prevent it from crazing or chipping after being burnt on the pieces of ware, which this colour is very susceptible of doing. 46 PROCESS 79. To make an Enamel painting Black. Take 4 Parts of Borax. 2 - - of Umber Calcined. 9 1 _ ~2 of Red Lead. 9 _ _ of Enamel Blue. 1 - - of Flint. 1 - - of Blue Calx.^ PROCESS 80. To make an Enamel printed Black. Take 1 Part of Umber Calcined. - - of Borax Calcined. \ - - of Blue Calx. ' ' i f PROCESS 81. To make a Superior painted Black. Take 8 Parts of painted Black. 1 - - of Enamel Blue. 1 - - of Enamel Purple. PROCESS 82. To make printing or lining Black. Take 1 Part of Copper calcined. 3 - - of Flux. Process 69. 47 The last process, called Copper Black, is a very fine colour, the obtaining of which altogether depends upon a pro- per temperature of heat being applied, for nothing is more fickle and uncertain, if in the least degree over fired the colour is destroyed, and becomes of a dirty green. The other blacks are called Umber Blacks, and will stand any degree of heat which is required in an enamelling kiln or muffle ; process 81 is a fine beautiful black colour, and is adapted for the painting of flowers and landscapes on porcelain. The umber to be highly calcined in a biscuit oven, but particular caution should be observed that it is the real Turkey umber, and not the English, which is of an inferior quality. The two first enamel blacks to be calcined in the usual way ; the materials of the two latter only want grinding. PROCESS 83. To make an Enamel Red. Take 1 Part of Green Copperas Calcined. 3 - - of Flux. Process 71. The greatest difficulty in preparing red is the calcination of the copperas ; calcine the copperas in a vessel exposed to the heat of an open fire, by which means it will dissipate all its volatile contents, and leave a residue of oxide of iron in pow'der, when it attains an orange or light red, the calcination is sufficiently accomplished, the residue is then washed repeat- 48 edly with boiling water, until the water becomes insipid and free from vitriolic acid. PROCESS 84. To make an Enamel Light Brown. Take 1 Part of Umber Calcined. 1 -- of Yellow under Glaze, i _ . of Copperas Calcined Red. ~ - of White Enamel. 5£ - - of Flux. Process 70. 3 - - of Flux. Process 71. PROCESS 85. To make an Enamel Dark Brown. Take 1 Part of Copperas Calcined Brown. 2 - - of Flux. Process 72 . \ - - of Flux. Process 69. These browns only require grinding before they are fit for use, the copperas for the purpose of making dark brown, will require calcining in the most intense heat of a biscuit oven ; the colour of it varies according to the temperature it undergoes, first white, then orange, red, and lastly brown. 49 PROCESS 80. To make an Enamel Blue Green, Take 42 Parts of Red Lead. 15 - - of Flint. 12 - - of Borax. 2f - - of Blue Vitrol Calcined. To these materials, after being calcined in an air furnace or glazing oven, must be added 12 parts of white enamel, then o-rind them all tog-ether for use. © © PROCESS 87. To make an Enamel Grass Green. Take 3j Parts of Blue Green Frit. 1 - - of Enamel Yellow. PROCESS 88. To make an Enamel Yellow Green, Take 2^ Parts of Blue Green. 1 - - of Enamel Yellow. PROCESS 89. To make an Enamel Yollow. Take 1 Part of Naples Yellow. 2 - - of Flux. Process 69. I - - of Flux. Process 71 G 50 PROCESS 90. To make an Enamel Orange. Take 1 Part of Orange under Glaze. 2 - - of Flux. Process 69. 1 - of Flux. Process 72. PROCESS 91. To make an Enamel Purple Distance. Take 2 Parts of Enamel Purple. 3 - - of Oxide of Manganese. © 12 - - of Flux. Process 71. In the several annexed Receipts for enamel colours no process of calcination is necessary, the materials being ground together and dried, afterwards mixed up with spirits of tur- pentine, is sufficient. PROCESS 92. To make a Cornelian Red. Take I Part of Chromate of Iron. - - of Flux. Process 72. This fine colour is produced from the chromate of iron, or the yellow oxide of chroma, which has a greater affinity for lead than an alkali, consequently the flux prescribed is the only one which is susceptible of yielding its proper colour, as 51 those fluxes which contain a large proportion of borax are very prejudicial, destroying the colour, and with the greatest difficulty forming any affinity at all, therefore should be avoided. The flux used should be highly calcined until it assumes a dark orange coloured glass. PROCESS 9:3. To make an Enamel Pomona Green. Take 1 Part of Oxide of Green Chroma. 2^ - - of Flux. Pi •ocess 69. 1^ - - of Flux. Process 72. This fine beautiful green is simply prepared by only grinding the above ingredients, and produces that dark colour equal to the French green, provided the oxide is genuine ; and by adding a proportion more of flux and white enamel, there still will be a rich tint, though weaker and lighter in colour. PROCESS 94. To make Burnish Gold from Brown Gold. Take 12 Parts of Brown Oxide of Gold. 8 - - of Quicksilver. 2 - - of Oxide of Silver. 1 - - of White Lead. G 2 52 Put the whole of these ingredients into an erthenware mortar, and triturate them until the whole is amalgamated, the mercury being the solvent fluid, very readily combines with the rest, to which it communicates more or less of its fusibility, after which, grind them very fine with spirits of turpentine. PROCESS 95. To make Burnish Gold from Green Gold, Take 12 Parts of Green Gold. 7^ - of Quicksilver. 1^ - - of Oxide of Silver. 1^ - - of Gold Flux. This is prepared first by dissolving and incorporating the gold with the quicksilver, to accomplish which, the gold is put in an earthenware vessel on an open fire, and when heated red hot, take four times its weight of mercury, and pour it in ; the mixture, to be stirred with a little iron rod; the gold will be dissolved spontaneously, it is then thrown into a ves- sel full of water until it coagulates and becomes manageable, much of the mercury is then pressed through a piece of leather, and the rest dissolved by a quantity of nitrous acid, the acid is afterwards poured off, the gold remaining is repeatedly washed with boiling water as often as needful, it is then dried and mixed up with the other ingredients, and ground with spirits of turpentine for use. PROCESS 96. To make a Bronze Gold. Take 2 -J- Parts of Burnish Gold. 2 - - of Oxide of Copper. 1 - - of Quicksilver. \ - - of Gold Flux. Having dissolved the copper in aqua fortis, it is again separated from its solvent and falls to the bottom of the vessel by the addition of iron, — the precipitate of copper may be in- creased or diminished at discretion, which makes the bronze richer or poorer in colour according to the proportion of bur- nish gold contained in the mixture. It is chiefly used for ornamenting the handles and heads of jars, vases, &c. and occasionally intermixed with burnish gold. PROCESS 97. To obtain a Solution of Gold. Take three parts of muriatic acid, and one part of nitric acid ; these proportions form an aqua regia, called nitro muri- atic acid, the only true solvent of gold. Put 40 dwts. of this mixture in a small bottle, to which add 5 dwts. of grain gold, the solution will immediately commence, and may be observed by the effervescence w hich arises at the time ; when the solu- tion is complete, the whole of the gold will he dissolved, which will be accomplished in about two hours if the acids be genu- ine, but when they are not, it will be requisite to apply heat to assist in facilitating the solution. 54 PROCESS 98. To obtain a Solution and Oxide of Silver. Take one part of nitric acid, and three parts of boiling water ; these proportions form an aqua fortis, which will dis- solve one-third of its weight of silver before the acid is per- fectly saturated. To precipitate the metal, the solution must be diluted with five times its quantity of water, then add a portion of common salt, stirring it all the time, and immedi- ately a white precipitate will fall to the bottom of the vessel » the liquor must then be decanted off and boiling water repeat- edly added, until the water is quite insipid. This precipitate is the pure oxide of silver, and is the same as that used in the preparation of burnished gold and in staining of glass. I PROCESS 99. To obtain a Solution of Tin. Take two parts of nitrous acid, and one part of muriatic acid, with an equal part of water ; these proportions form an aqua regia ; caution should, however, be particularly observed, that the solution is not too hastily effected, if so, the tin will be too much oxidated and too little of it will be contained in the solution ; in order, therefore, to obtain a strong solution, (which is so very requisite) add granulated tin by small pieces at a time, so that one piece be dissolved before the next is added. This aqua regia will dissolve half its weight of tin ; 55 the solution, when properly obtained, is of a redish brown or amber colour ; but when it assumes a gelatinous substance the solution is defective. PROCESS 100. To make an Enamel Purple. Take 4 Parts of Gold in Solution. 1 - - of Tin in Solution. To prepare enamel purple the first step is to procure a vessel to contain fifty parts ot water about the temperature of blood-heat, to be well mixed with the solution of gold, and then add the solution of tin by dropping it into the menstruum, at the same time constantly stirring it with a strong feather, which will produce a fine purple colour liquor ; but it will be necessary to add a few drops of the solution of silver, which will much assist to raise the colour and beauty of the purple ; to help the precipitation of the gold from its solvent (provided the precipitation does not immediately take place) add a large proportion of boiling water or a small quantity of sal amoniac and a precipitate will instantly be procured ; the clear liquor must then be decanted otf, and the boiling water repeated until it is completely insipid. The residue consists of the oxides of gold, tin, and silver in combination, and is the only substance which has the property of communicating the purple colour to enamel glass ; after the precipitate is prepared the 56 flux must be added, the proper quantity will solely depend on the fusibility or softness of the flux, and as the operation in a great measure depends on observation, a few experiments by the operator will be found useful, independent of the accuracy of the receipt. To the purple precipitate may be added from 30 to 45 parts of flux, Process 71, according to the strength of colour intended to be made. PROCESS 101. To make an Enamel Rose Colour. Take 3 Dwts. of Gold in Solution. 60 Leaves of Book Silver. 2 \ Lbs. of Flux, Process 69. To prepare enamel rose colour procure a vessel that will contain 10 parts the quantity of hot water as for the solution of gold, then mix them together while the water is at the tem- perature of 190 degrees of Fahrenheit’s thermometer, add pul- verized sal amoniac rather copiously, at the same time briskly stirring the mixture with a strong feather, until the appearance of a decomposition takes place, which will soon be observable by the gold being precipitated from the menstruum in the form of a fine yellow powder ; when that is accomplished, let the vessel stand undisturbed a short time to allow the precipitate to subside, then decant the liquor off, and still add boiling water repeatedly to the precipitate until the water is perfectly 57 insipid ; in the next place put it on a plaster bat to dry, after which it must be mixed up with book silver and flux, according to the proportions given above, and well triturated in a mortar, then send it to the mill to be ground, when it will be in a pro- per state for use. This colour is supposed to be best when of a purple tinge, which may be produced by merely calcining the preparation to the heat of ignition previous to being ground ; if the colour be too dark, it is a demonstration that the mixture does not possess a sufficient quantity of silver ; if on the other hand it is too light, the silver must have been very plentifully added, therefore the operator must add or diminish accordingly. It will not be amiss to remind the young opera- tor of the great danger attending the use of oxide of gold, a caution which ought to be strictly attended to, the gold being precipitated by the means of sal anionic, for which it has an affinity, will consequently readily unite with it, thereby acquir- ing the property of fulminating, and when gently heated or smartly struck with any hard instrument will immediately detonate. The chief point then to be obtained is to obviate that dangerous quality by depriving the gold of its salt, which may be accomplished by repeated adulteration with boiling water. H 58 PROCESS 102. To make a Gold Lustre. Take grain gold and dissolve it in aqua regia, as in pro- cess 97 ; provided the acids are pure, the solution will be rea- dily effected without the assistance of heat. In this solution of gold it will be necessary to add a small portion of grain tin, viz. to 5 dwts. of gold in solution let 5 grains of tin be added ; an effervescence takes place when the solution is completed and in a proper condition to be mixed with the balsam ot sul- phur, ■*■*••• J . . The balsam of sulphur is likewise prepared in the follow- ing manner : take one part of the flour of sulphur, and six parts of essential oil of turpentine ; put them in a vessel over a slow fire until the oil boils and the sulphur is totally incorpo- 63 rated with it, which produces a red balsam ; let the mixture cool and the sulphur will fall to the bottom ; the liquor is then poured off, fresh oil added, and the same process repeated again. Ten parts of oil are required to one part of sulphur, to keep it in solution when cold; be sure that the oils are per- fectly genuine, otherwise the balsam will be spurious, and not fit for the purpose of making gold lustre. Having closed the various and intricate receipts of ena- mels, lustres, colours under glaze, fluxes, solutions, and oxides of various metals, &c . ; their combinations, names, and uses ; in order to make it a little clearer to the reader, let it be observed, that the basis of enamels are alkalies and lead, to which are added other metallic or mineral matters to give them the colour required; as gold for purple and rose colour, cobalt for blue, copper for greens, umber for black, chrome for cornelian red and pomona green, and copperas in various states of calcination for red and brown ; gold and platina for lustres, the former for gold and the latter for silver or steel lustre. The enamels, after being finely ground, should be thoroughly dried, then mixed up with turpentine, and used like other colours with a pencil, after which fused again, and vitrified bv fire. Spirits of tar may be substituted instead of turpentine in all enamels with the exception of blue, and colours pre- pared from chrome. With regard to the burning of them, the lustres will bear the highest temperature of an enamelling 64 heat ; the rose colour, cornelian red, and pomona green re- quire a less degree of heat, and are generally seated or placed in the middle of the kiln or muffle, as well as burnish gold ; other colours are not so susceptible of being destroyed by heat, consequently they will fire in any part of the kiln or muffle. The even surface of the various coloured grounds on china is produced by first laying the space wanted with linseed oil, previously boiled with a little red lead and a small portion of turpentine ; the enamel colour is then ground fine, and dusted on the oiled part with cotton wool, or laid on with a large camel hair pencil. The component parts of the different colours will be found as accurately stated as possible, and in reference to lustres, purple, and rose colour, the preparation principally depends on observation, therefore experiments will be necessary that a proper judgment may be formed, for bv discreet combinations and management all those beautiful variety of tints and shades are produced on china which now adorn the tables of the sovereigns of Europe. SECTION IV. RECEIPTS for preparing Zaffre and Cobalt Blue, with the various processes of smelting, refining, and Cal- cining. PROCESS 108. To procure the Regulus of Zaffre. Take 112 Parts of Zaffre. 57 - - of Potash, 18£ - - of Charcoal. This is the first process towards making blue calx, and is called running down, but more properly smelting. The char- coal being pulverized, and all the materials mixed up toge- ther are afterwards put into large sized crucibles capable of holding from three to four quarts, and filled quite full, then placed in a strong brick built reverberating furnace, com- mencing with a slow fire, and continued for some time, but as soon as it is heated to a red heat, it will then require a consi- derably stronger fire before the cohesion between the different particles is sufficiently destroyed. This operation will be com- plete in about ten hours, the weight of the regulus being from 66 thirty-one to thirty-three pounds ; on examining the scoria, if there remains mixed with it small pieces of metal not much unlike small shot, or when pounded, if the scoria has a bluish cast, it is an occular demonstration that the fire has not been strong enough ; there is but little danger to be apprehended from the most intense heat, provided the particles in fusion do not perforate the crucibles, which are made of a mixture of marls with a small quantity of sand. At the bottom of each cake of Regulus there will be bismuth slightly adhering, which is easily separated without the application of any great degree of heat, by placing the cakes upon an iron plate or pan, which will soon bring the bismuth into a state of liquifaction, and separated from the regulus. PROCESS 109. To refine the Regulus of Zaffre. Take 50 Parts of Regulus. 6 - - of Potash. 3 - - of Sand. When the regulus is deprived of its bismuth and pulver- ized, it is to be well mixed with a quantity of potash and sand, as before mentioned, then put in to considerably smaller crucibles holding about 1^ lb. in each, and fired in a reverbe- rating furnace, commencing with a slow fire and gradually increased for the space of about eight hours ; by that time the 67 regulus will have fallen to the bottom of the crucible, and the scoria found at the top will be of a blackish green, therefore it will be indispensably necessary that another course of refining should take place, in order that the regulus may be obtained in a more perfect state of purity. PROCESS 110. To refine the Regulus of Zalfre a second time. Take 50 Parts of Refined Regulus. 6 - - of Potash. 3 - - of Sand. These materials to be mixed, fired, and treated in every respect the same as in the former process of refining, but a further fusion is required in order to purge the sulphurous parts which adhere to the metal, and which in consequence of the fluxes attracting and absorbing it, is frequently found mixed with the scoria ; the regulus will then be sufficiently purified for the next operation. PROCESS 111. To procure Blue Calx from Refined Regulus of Zaffire. Take 30 Parts of Refined Regulus. 1 - - of Plaster. \ - - of Borax. 12 68 These materials to be made very fine, and exceedingly well mixed up together, after which put the mixture in earthenware biscuit cups made one and a half inch high, 3 inches in diame- ter, and one-half inch thick, filled nearly to the top, set them in a reverberating furnace, the fire to be increased until the mix- ture is perceived to be in a state of fusion or eliquated, the same degree of heat must be continued for about six hours after- wards, and then the fire hastily slackened ; this operation of calcining will occupy from twelve to thirteen hours ; at the top of the cups will be found a blue calx separated from the nickle ; but as a large proportion of blue will still remain in the nickle when sunk to the bottom of the cups, it will be necessary in order to procure the whole of the blue contained, to pursue precisely the same method over again, viz. the metal mixed up with the plaster and borax, and calcined in the manner described as before, and then without doubt it will yield all the remainder of the blue, which will be found as before at the top of the cups, and the nickle sunk to the bottom ; the blue calx obtained by the first process is the best and purest; however, the first and seconds, as they are called, are mixed together, and sold under the appellation of zaffre blue. 69 PROCESS 112. To make Cobalt Blue. Take 60 Parts of Cobalt ore. 50 - - of Potash. 25 - - of Sand. 10 - - of Charcoal. % Let these materials be mixed well together and put into crucibles considerably smaller than those adopted for the smelting of Zaffres, about l|lb. of this mixture will be suffi- cient in each crucible, the remaining parts of the process are the same in every respect, and to be attended to in the same manner as described in the process of smelting zaffre, when regulus of Cobalt will be properly obtained. PROCESS 113. To refine the Regulus of Cobalt. Take 50 Parts of Regulus. 6 - - of Potash. The regulus must be pulverized small, and mixed up with the other materials ; instead of using crucibles as in the refin- ing of regulus of zaffre, they should be earthenware cuppels in the shape of the old pickle jar or bottle, with a flange top rather larger than half pints, to contain about one pound of the mixture. Cobalt ores vary very much both in the quality and quantity of blue they contain, whether the ore be poor or 70 rich the same process is to be adopted ; the operation of refin- ing must be as often repeated as is necessary, i. e. until the scoria is of a bright colour, and of a slight blueish hue, which requires in general about three times, and in some instances five times refining before the regulus is sufficiently purged and purified for the next operation. PROCESS 114. To roast refined Regulus of Cobalt. This process is performed by spreading the purified metal finely pulverized half an inch thick on flat pieces of earthen- ware covered with flint, and placed in a reverberating furnace, and a moderate degree of heat applied for a few hours ; care and observation will be particularly required that the metal by an excess of heat does not get into a state of liquifaction, if so, the object will be defeated by expelling the arsenic which it contains ; the metals from which the cobalt is with the greatest difficulty disengaged are arsenic and nickle* the former is effected by being exposed to a gentle heat, which is called roasting, the latter by repeated fusions and calcining or calxing. PROCESS 115. To procure Blue Calx from the refined Regulus of Cobalt. Take 30 parts of refined Regulus. 1 - - of Plaster. l : - - of Borax. 71 The regulus after being calcined (which is also called roasting) is to be pulverized quite fine and completely mixed with the plaster and borax, and the same method strictly adopted and observed as that pursued in calxing the refined regulus of zaffre, and as both preparations are in reality per- fectly alike, consequently the operator cannot do better than refer to that process. Having thoroughly described the method of manufacturing cobalt and zaffre blue, through various and intricate processes, together with the mode of operation, it would be impossible to state the exact quantity of fire required in each operation, for the effect of the fire bears an exact proportion to the mass of the body, the size of the furnace, and the strength of the fire employed. Zaffres are of a dark grey colour about the fineness of sand. Cobalt ores are of a grey colour, shining, hard and ponderous ; certain arsenical ores which are similar in appear- ance have frequently obtained the name of cobalt, but falsely 5 calx of cobalt and zaffre dissolve in the marine acid in great abundance, if the solution be green it is owing to the calx con- taining nickle ; if it be pure, the solution yields crystals of a red colour inclining to blue. ' SECTION V. spiimtmu attir Joining of ©lass, INTRODUCTION. THAT this is one of the most ancient of the fine arts can scarcely be doubted, and it is even probable that immediately after the invention of making glass would follow attempts to colour and ornament it. The opinions as to its origin are as various as they are numerous. Anthony Neri who flourished in the fifteenth century, stated it to be as old as the time of Job, that divine author making mention of it; we have the very manner of the invention described by Pliny, who informs us that Sidon, in Syria, was famous for glass, and glass houses, it is very likely this was the first place where glass was manu- factured, the same being positively asserted by various histo- rians. A moments reflection on its nature and manner of production would almost induce one to believe it nearly co- eval with the art of potting, and the making of bricks, for scarcely can a kiln of either be burnt, but glass must be superficially formed about those parts where the fire has been the most intense, and from the various and numerous combi- 74 nations that will produce it under sufficient heat, together with the simple and easy method of its formation* The primitive method of painting glass, (or rather of the most ancient pro- duction met with) was quite simple ; to accomplish the repre- sentation of any object, they merely arranged in some sort of order, different pieces of glass of various colours, upon which they added bold and striking shades with a chaste colour using it throughout the design, there are some specimens wherein this colour has been used alone on plain glass, and the effect produced is really great considering the simplicity of the style ; this method is generally looked upon as the original. Thus far the ancients proceeded in water colours which they had a most excellent method of causing to adhere firmly to the glass. In the course of time the art was greatly improved, methods having been discovered of incorporating the colours with the glass itself, thereby producing in it the most beautiful and vivid tints ; the art was then found applicable to the adorning of churches, palaces, &c. and soon attracted the taste of the great and opulent ; it is somewhat singular that in most of these ancient productions we should see such excellent colours, and at the same time the design and execution generally stiff and ill proportioned, although the taste for painting and sculp- ture at that time was extremely correct ; they had two ways in which they produced these colours, in one the colour was diffused throughout the substance of the glass, in the other, the colour was given by coating the glass on one side not more 75 than one third of a line in thickness with a peculiar vitrious mass prepared for the purpose. The modern method of prac- tising- this art is very different from that of the ancients, all their principal colours were made at the glass houses, and amongst their works there is scarcely to be seen two ground colours on the same piece of glass, where as it is now possible to produce every colour used in the art on the same piece, then by the aid of vitrious colours of easy fusion, and the great facility which various stains can be given to glass, we are enabled to complete a figure or landscape, with every species of ornament on a single pane ; a circumstance with which the ancients were not acquainted. These colours are composed of various glasses which perfectly vitrify at a low temperature, and contain metallic oxides which are the colouring matter. The principal stains are produced by the oxides of gold, silver, copper, tin, and iron. That beautiful tinted ruby colour stain of the ancients, was produced by a due proportion of the oxides of gold and silver ; it has been attempted in the present day, with tolerable success, but it is more than probable the composition of the glass itself renders it a critical operation, and difficult to accomplish ; other particulars respecting the proper treatment of the colours and stains will be found to accompany each process, or at the conclusion. 76 RECEIPTS Of Stains and Enamel Colours for Painting Glass, also the Process of Etching and Coating Glass. PROCESS 116. To make Ked, Orange and Yellow Stains for Glass. Take 12 Parts of Green Vitriol Calcined. 1 - - of Oxide of Silver. To prepare these stains the vitriol must be calcined to a redish colour, and repeatedly washed with boiling water until it is completely freed from its acid, which will be known by the water being insipid to the taste, then triturate the silver and vitriol together in a mortar, after which grind them up with spirits of tar for use. If the design on the glass is to be figures or landscapes, the stain is laid on in various thick- nesses conformable with such design, and when the glass is burned, the stain or coating is washed off with warm water which will bring to view every part of the figure,