RECOMMENDATIONS. Woolwich Dock- Yard, 17th April, 1851. These are to certify, that James Larkin was employed as leading man of brass founders, in the Steam-engine Factory of this Yard, from the 30th day of November, 184.0, to the 12th day of April, 1851. During the last 2 J years he has been under my superintendence, and his capability as a workman has been quite satisfactory to me. EOT. HUMPHREYS, Chief Engineer. Philadelphia, December 7, 1852. Gentlemen : Mr. James Larkin has been conductor of the Brass Foundry Department in our establishment for the last twelve months. We have every confidence in his ability, and consider him to be at the head of his profession. We have taken a cursory view over the work he is about pub- lishing, and feel fully satisfied that it is what is much needed in the Trade. It is a desirable work for the pocket — for the artist as well as the mechanic. Respectfully yours, &c, REANEY, NEAFIE & CO., Penn Works. P) ii RECOMMENDATIONS. Philadelphia, December 2, 1852. We have taken a hasty view of Mr. Larkin's "Brass and Iron Founder's Guide." It is a work much wanted, and would doubt- less meet a ready sale. Yours, most respectfully, MERRICK & SON, Engineers, Mechanicians, Sfc. t Washington Street. Philadelphia, December 2,. 1852. I have had some conversation with Mr. James Larkin, and examined part of the manuscript of a work he intends publish- ing, viz. : " The Brass and Iron Founder's Pocket Guide," and I have reason to believe that it will be very useful to persons engaged in that branch of business. JOHN AG NEW, Franklin Works, Vine Street. Philadelpiha, December 3, 18-32. I have held some conversation, as well as examined the manu- script of a book which Mr. James Larkin is about publishing, upon the subject of Iron and Brass Founding, which I believe is a work much needed by those engaged in these branches of manufacture, and I feel it will prove a great desideratum for those so engaged. HENRY HOMER, Brass Founder, §c, 77 Race Street. THE PRACTICAL BRASS AND IRON FOUNDER'S GUIDE. THE PRACTICAL BRASS AND IRON FOUNDER'S o^rfo^; GUIDE: iAAaM y A CONCISE TREATISE ON THE ART OF BRASS FOUNDING, MOULDING, ETC. •WITH NUMEROUS PRACTICAL RULES, TABLES, AND RECEIPTS GOLD, SILVER, TIN, AND COPPER FOUNDING; PLUMBERS, BRONZE AND BELL FOUNDERS, JEWELLERS, ETC., ETC. BY JAMES IaRKIN, CONDUCTOR OF THE BRASS FOUNDRY DEPARTMENT IN REANET, NEAFIE & CO.'S PENN WORKS, PHILADELPHIA. PHILADELPHIA: A. HART, late CAREY & HART, 123 CHESTNUT STPvEET. 1853. Entered, according to the Act of Congress, in the year 1853, by A. HART, in the Clerk's Office of the District Court of the United States, in and for the Eastern District of Pennsylvania. ^-SW? E. B. MEARS, STEREOTYPER. T. K. & P. G. COLLINS, PRINTERS. PREFACE. The world at present groans under, a load of new publications on every branch of science and art; with which no former period of our literary annals can for a moment be compared. The most assiduous students, unable to peruse a thousandth part of the works which are daily soli- citing their attention, are quite perplexed and dis- tressed about what to choose and what to reject. This I have frequently found to be the case with myself, and while debating the question in my own mind, have lost, in doubt and uneasiness, the time I meant to set apart for practical manipu- lation. Impressed, therefore, with the unspeakable dis- advantages that result from the circumstances just (?) viii PREFACE. stated, and anxious to save others, in some degree, from that unpleasant dilemma in which I have myself been so often placed, I have resolved on the present publication, which I hope will to a very great extent accomplish the useful object I have in view. With what judgment, however, the design has been formed, and with what skill it has been exe- cuted, it becomes not me to determine — that ques- tion, to the result of which I am deeply alive, remains now with a higher tribunal. During the last fifteen years I have, from time to time, contributed papers to well known mechanical and philosophical publications, on subjects herein discussed. These I have carefully revised for the present work, and have added much information gleaned in the field of experience, and from the arcana of science. I would add in conclusion, that I have been practically employed in the business for thirty-four years, having conducted the work, in all its branches, at Messieurs Sandford et Varreles, Hue de Eoche- chourt, one of the largest ateliers in Paris, as well PREFACE. ix as at the British government works, steam-engine and ship-building yard, Woolwich, London, for the last eleven years — so that the reader may relieve himself of all doubt and difficulty in the matter. James Larkin. Philadelphia, 1853. CONTENTS. PACE On the Properties of the Metals . . . .19 On Metallic Alloys ..... 32 Table of Metals . . . . . .37 Conducting Powers of Metals .... 38 Table of Experimental Results as to some of the Chemical and Physical Properties of the Atomic Alloys of Copper and Zinc, and of Copper and Tin ... 40 On Founding . . . . . .42 On Brass Founding ..... 43 Copper . . . . . . .45 On the Reduction of Copper .... 46 Tin ....... 47 On the Reduction of Tin, Grain and Block Tin . 49 On Zinc ....... 50 On Lead ...... 51 On Antimony . . . . . .52 Order and Working of Metals .... 53 On Copper and Tin . . . . .54 Bronze for Cannon, Statues, &c. ... 55 On Bell Metal . . . . . .55 On Copper and Tin Mixtures .... 56 Alloys of Copper and Zinc . . . . .57 Alloys of Copper, Zinc, Tin, and Lead . . 59 Manheim Gold . . . . . ,60 (ID xu CONTENTS. Pinchbeck Princess Metal Tombac Artificial Gold Fine Brazing Solder Remarks Facing . Metallic Moulds Pewtering Complex Objects On Bell Founding On'Gun Founding . On Figure Casting Brass Mirrors Copper . Metals Surface of Metals Blanched Copper British Weapons and Tools in Bronze, anciently called Co- rinthian and Syracuse Brass On Brass ....... Casting in Plaster ..... To Transfer Engravings to Plaster Casts . To Varnish Plaster Casts .... To Cast Concave or Convex Moulds of Medals on Tin-Foil, with Plaster ...... To Cast Vegetables, Insects, Small Birds, Frogs, Fish, &c, in Plaster Moulds ..... To Prepare a Metal for the Above . Sir Isaac Newton's Fusible Metal Rose's Alloy ...... PAGE 60 61 61 61 61 62 63 64 65 66 67 68 70 72 72 72 73 73 CONTENTS. xiii PAGE Dr. Dalton's Fusible Alloy .... 80 To Cast in Wax . . . . . .81 To Cast in Sulphur ..... 82 To Cast in Glue . . . . . .83 To make a Fine Glue, wherewith you may cast Curious Medals . . . . . . .83 To Cast in Bread Paste .... 84 To Cast Figures in Imitation of Ivory . . .85 Rice Glue Statuary ..... 85 A Composition for Ornaments . . . .86 Alloys, Amalgams, &c. .... 87 Native Alloys . . . . . .88 Density of Metals ..... 89 Bronze, Bell, and Speculum Metals . , .90 Combination and Chemical Action ... 91 Yellow Brass . . . . . .92 To make Copper Medals and Medallions . . 93 Amalgamation of Metals . . . . .94 Bismuth ...... 97 On Friction . . . . . .98 On Bells ...... 100 On Fluxes . . . . . . .101 Fusing and Melting Points . . . .103 Fluidity . . . . . . .104 Anti-Friction Metals . ... 105 Table for Converting Decimal Proportions into Divisions of the Pound Avordupois .... 106 Keller's Statue Composition .... 107 The Chinese Packfong . . . . .108 Copper . . . . . . .108 Silver Steel . . . . . .109 9 XIV CONTENTS. Copper and Antimony Antimony and Tin, Copper and Bismuth Bismuth and Lead . Full Measure of Capacity of Tin and Lead Brilliants of Fahlun Queen's Metal . Tin and Zinc Tin and Iron To Silver Copper Mosaic Gold To Bronze Brass, &c. Lacquers Green Bronze Liquid To Silver Ivory Zincing Metal Plates Cast Metal Balls Cast Iron Pipes Cast Metal Cylinders Specific Gravity and Weight of Materials Specific Cohesion and Strength of Metals Direct Cohesion of Metals Resistance of Metals to Pressure . Resistance of Metals to Torsion Gold and Silver Solders Brass Solder • Method of Soldering Gold and Silver To Cleanse Silver after it is Soldered . Silver Solder for Jewellers . Trinket Composition Silver-Plate and Medal Alloy CONTENTS. xv Gold Coin of America Alloy- Solder for Iron Soldering and Burning Metals Plumber's Solder . Compositions of Pewter White Metal Mosaic Mixture Silvery-Looking Metal Metal for Flute Valve Keys German Titanium . Spanish Titanium Britannia Metal Columbia Metal Type Metal German Silver . Speculum Metal Remarks Platina On the Properties of Arsenic Fontainemoreau's New Alloys Bronze, Copper, and Brass On Zinc as a Protective Covering for Iron ; and the Adap- tation of the Process of Electro-Deposition for that Pur- pose .....•• Water in Pipes ....•• On Crucibles ..•••-• Plumbago .....•• Hardening Steel ..... On Boron ....••• On Sulphur ...... Selenium .....•• of Zinc, a substitute for PAGE 129 129 130 135 135 135 136 136 136 136 137 137 138 138 139 140 142 144 145 147 152 162 163 166 167 167 170 172 xvi CONTENTS. PAfiE On Chlorine . . . . . .373 Metallic Oxides . . . . . .175 Appendix ...... 177 To Brown Gun Barrels . . . . .179 Varnish for Gun Barrels that have undergone the Process of Browning . . . . . .180 Ethereal Solution of Gold . . . .180 To Coat Small Nails, &c, with Tin ... 181 Bronzing Electrotype Casts — Chemical Bronze . 182 Black Lead Bronze ...... 184 Carbonate of Iron Bronze .... 185 To Tin Iron . . . . . .185 Liquid Glue 180 Artificial Fire-Clay . . . . . .186 A Cement which Resists the Action of Fire and "Water 187 Cement for the Joints of Cast Iron . . . 188 Niello-Metallic Ornaments . . . .188 Tracing Paper . . . . . .189 To Fix Drawings . . . . .190 Antidote to Arsenic . . . . .191 To Soften Ivory ..... 191 To Separate the Metallic Portion from Gold and Silver Lace ....... 191 Blueing and Gilding Steel . . . . .192 To Harden Steel Dies ..... 193 Portable Glue . . . . . .194 Prevention of Corrosion .... 194 Cement . . * . . . .195 Soluble Glass ...... 195 Japanning . . . . . . .196 To Preserve Polished Steel from Rust . . 198 CONTENTS. xvii PAGE Cement for Attaching Metal to Glass . 198 Varnish for Coloured Drawings 199 Japanners' Copal Varnish . . 199 Soft Varnish . 199 Hard Varnish . . 200 Flexible Varnish . 200 French Polish . . 200 Brunswick Black . 201 Mordant Varnish . . 201 Another . 202 Another . . 202 Another . . 202 Another , . . 203 Superior Green Transparent Varnish . 203 Etching Varnish . . 204 2* BRASS AND IRON FOUNDER'S GUIDE. ON THE PROPERTIES OF THE METALS. The metals constitute by far the most numerous class of undecompounded bodies in chemical arrange- ments. They are, in general, readily distinguished from other substances, by characters which every one recognises ; but to an ordinary observer they do not appear to differ essentially from one another; they seem rather to owe their differences of colour, and other physical properties, to a tinge and cha- racter given to them by adventitious circumstances, and perhaps some trifling admixture of other sub- stances. This opinion is natural, and was at one time the prevailing doctrine of the learned. When chemistry began to be developed in the hands of the alchemists — upon whom it has been fashionable to heap ridicule for the extravagances of their notions — it was generally admitted that all (19) 20 PROrERTIES OF THE METALS. metals were essentially the same ; and as gold was reckoned the most precious, it was assumed to be the pure basis of all the other metals. Upon this assumption, the aim of alchemy was direct and ra- tional; its object was to separate the substance, whatever it might be, the presence of which pre- vented lead and other base metals from being gold. It is hardly necessary to observe that these efforts failed. Accordingly modern chemists, taught by experience to believe the required decomposition impossible, have come to the matter-of-fact conclu- sion that when metals are of different colours, degrees of hardness, lustre, ductility, fusibility, and so on, that they are of different natures. Although the metallic character be readily and popularly recognised, it is difficult to define it with accuracy. With the single exception of quicksilver, the metals are all solid at ordinary atmospheric tem- peratures ; but their most striking property is their lustre, which is so remarkable as to be at once understood by the expression, metallic lustre. This property belongs, in a greater or less degree, to every metal : it is the property of strongly reflect- ing light, and seems connected with a certain state of aggregation of the metallic particles. The same PROPERTIES OF THE METALS. 21 property is however possessed, at least superficially, in a minor degree, by mica, animal charcoal, silenium, and polished indigo — bodies not at all metallic. In consequence of the peculiar power of the metals to reflect light, they are no less remarkable for their opacity than their lustre. Thus, silver- leaf, only one hundred-thousandth of an inch in thickness, is perfectly opaque ; and leaves of other metals, in general, allow no light to pass through their substance. Yet gold-leaf, of the two hundred- thousandth part of an inch in thickness, would seem, as observed by Sir Isaac Newton, to transmit green rays of light; and it is probable that, could we obtain films of other metals of equal thinness, they would be found to allow certain rays to pass through them. The fact, as observed with gold, has how- ever been ascribed to the porosity of the metal, the rays transmitted passing through an infinite number of minute fissures in the thin leaf. This, it must be admitted, is quite compatible with perfect opacity of the substance of the metal ; the leaf, like a piece of wire gauze, allowing the light to pass only through its interstices, and not through the solid metal itself, which may be perfectly impervious to all luminous rays. 22 PROPERTIES OF THE METALS. The polished metals are imperfect radiators and receivers of heat, but they are excellent reflectors, both of light and heat : hence their peculiar fitness for the construction of mirrors. They are also, in general, excellent conductors of heat, and most of them also of electricity, though probably not all. The greater number of them are susceptible of assuming the crystalline form. With several of them this may be effected by fusion and slow cooling. Thus, by suffering the melted metal in a crucible slowly to concrete externally, and then perforating the solid crust, and pouring out the liquid interior, the cavity so formed will be found lined with crystals. When a metal is precipitated by another, it is often deposited in a crystalline state. Thus, if a little mercury be thrown into a solution of nitrate of silver (lunar caustic), the silver is precipitated in beautiful crystals. The same phenomenon occurs, when a bit of zinc is suspended in a salt of lead. In like manner, if a stick of phosphorus be immersed in a silver solution, it becomes incrusted with beau- tiful metallic crystals, which after some time per- fectly encase the phosphorus. Gold is also some- times deposited in crystals from its ether solutions ; and during the decomposition of several of the PROPERTIES OF THE METALS. 23 metallic solutions, by galvanic electricity, especially when low powers are employed, beautiful metallic crystals are often obtained. This is readily verified with solutions of copper and silver salts. The metals possess, in different degrees, a pecu- liar tenacity, which, in its greatest perfection, ren- ders them malleable and ductile — that is, capable of being extended under the hammer, and drawn into wire — properties which belong to no other species of matter. Thus, gold and silver may be beaten into leaves almost inconceivably thin ; cop- per, tin, platinum, and lead, possess the same pro- perty, but less perfectly ; others are entirely desti- tute of it, as arsenic, antimony, and cobalt. These last can indeed be readily reduced to fine powder, and hence they are distinguished as brittle metals. Those metals which are malleable are also ductile ; these properties are analogous, but do not appear to bear a uniform relation to each other, among the metals possessing them. Gold and silver are, how- ever, the most ductile, as they are the most malle- able. Thus, a grain of gold may be extended by hammering, so as to cover fifty-two square inches of surface, or it may be drawn into 500 feet of wire, and by enveloping it in silver, it may be extended to 700 feet. In like manner, platinum, which is in- 24 PROPERTIES OF THE METALS. ferior to copper and tin in malleability, lias been drawn into wire not more than the 3ogot»th of an inch diameter — a degree of fineness, which, except under certain circumstances of illumination, is in- visible. Iron may be drawn into wire as fine as the human hair; copper is less ductile, and zinc, tin, and lead, can be drawn into wire, but considerably less fine. The brittle metals, as might be supposed, do not draw. The following table shows the order which the metals bear to one another, in respect to these pro- perties : — A TABLE SHOWING THE OR/DEE. WHICH THE METALS BEAR TO ONE ANOTHER IN RESPECT TO THEIR PROPERTIES : — Order of Malle- ability. Order of Ductility. Order of Tenacity. Order of Brittle- ness. Gold, Gold, Iron . .1000 Antimony, Silver, Silver, Copper 550 Arsenic, Copper, Platinum, Platinum 494 Bismuth, Tin, Iron, Silver . . 349 Cerium, Cadmium, Copper, Gold . . 273 Chromium, Platinum, Zinc, Zinc . . 199 Cobalt, Lead, Tin, Tin . . . 63 Columbium, Zinc, Lead, Lead . . 50 Manganese, Iron, Nickel, Molybdenum, Nickel, Palladium, Palladium, Cadmium, Iron wire 1-tenth in. diameter is capable of sustaining 5001bs. Tellurium, Titanium, Potassium, avoirdupois. Tungsten, Sodium, Uranium, Solid mercury, Rhodium. PROPERTIES OF THE METALS. 25 are scratched by calc-spar. Few of the metals when pure are very hard, and some are so soft as to yield to the nail. The fol- lowing table of hardness is given from the experi- ments of M. Dumas : — Titanium, Tungsten, ? are harder than steel. Manganese, Platinum, Palladium, Copper, Gold, Silver, Tellurium, Bismuth, Cadmium, Tin, Chromium, Rhodium, Nickel, Cobalt, Iron, Antimony, Zinc, Lead yields to the nail. Potassium, Sodium- scratch glass. are scratched by glass. are soft as wax at 60°. Mercury is liquid above minus 39°. 26 PROPERTIES OF THE METALS. In respect to fusibility — that is, the capability of being melted by heat — the metals differ from each other as widely as in any other respect. Thus, mer- cury requires to be cooled down to minus 39° before it becomes solid, whereas the melting point of pla- tinum is somewhere beyond 3280°. Potassium melts at 140°, and sodium at 190°. Tin becomes liquid at 444°, bismuth at 500°, lead at 600°, zinc at 770°, and antimony at 800°. Silver, gold, and copper, require a bright cherry-red heat to melt them (about 2000°) ; cast iron, nickel, and cobalt, a white heat (about 2800°) ; and manganese, and malleable iron, the highest heat of a smith's forge (about 3000°). The highest temperatures of our furnaces are only sufficient to agglutinate very imperfectly the metals molybdenum, uranium, tungsten, and chromium ; and titanium, cerium, osmium, iridium, rhodium, platinum, and columbium, require the intense heat of the oxy-hydrogen blow-pipe, or that of voltaic electricity, to fuse them. Some of the metals, when exposed to heat, not only melt, but, obeying the general law of liquids, boil and evaporate when the heat is sufficiently high. Thus, mercury, zinc, cad- mium, bismuth, tellurium, and antimony, boil and evaporate at a red heat ; and, in a vacuum, mercury is known to evaporate at ordinary atmospheric tem- PROPERTIES OF THE METALS. 27 peratures (above 50°) ; silver and lead require a high heat to vaporize them ; tin a still higher heat ; and gold will only evaporate slowly under the most intense heat that can be applied. Several of the other metals, as iron and nickel, cannot be made to evaporate in the most intense heat with which we are acquainted. Arsenic, on the other hand, eva- porates without melting. There are several of the metals which emit a pecu- liar odour, especially when rubbed, or have their temperature slightly raised. This is particularly the case with copper, iron, and tin. The vapour of others is very remarkable. The arsenic vapour has the smell of garlic; that of tellurium smells like horseradish ; and osmium takes its name from the smell of its vapour (osme, odour). Some of the metals have also a peculiar taste when applied to the tonsue, which has been ascribed to their electrical condition ; but it must be remarked that many of the most oxidable metals are entirely destitute both of taste and odour. A high specific gravity was reckoned one of the most marked characteristics of the metals, till the discovery of the metallic basis of the alkalies by Sir Humphrey Davy. So intimately indeed was the metallic lustre associated in the mind with great 28 PROPERTIES OF THE METALS. weight, that when a piece of potassium was put, for the first time, into the hand of an eminent teacher of chemistry, in admiring its perfect metallic cha- racter, he poised it upon the finger, and exclaimed, " How heavy !" and the prejudice was only removed by seeing it float upon water. The list of metals, however, includes the densest forms of matter with which we are acquainted ; and, although great weight cannot be regarded as a universal property, we hare few examples in which the density is less than the density of water. These examples comprehend only potassium and sodium ; all other metals are of greater specific gravity, up to platinum, which is twenty-one times the weight of an equal bulk of water. The degrees of facility with which the metals combine with oxygen differ widely. Some, by mere exposure to the atmosphere, absorb its oxygen with great rapidity : such is the case with potassium and sodium : others absorb it more slowly, as manganese, iron, and arsenic ; and lead and copper still more slowly. Others, again, do not oxidate by exposure to air, unless at a high temperature ; this is the case with tin, zinc, mercury, antimony, bismuth, and cobalt, which absorb the oxygen readily when in a PROPERTIES OF THE METALS. 29 state of fusion. Others, again, do not oxidate by- exposure to air and heat, or by immersion in water, as gold and platinum ; the same is nearly true of nickel and silver. The tendency of the metals to combine with oxygen appears, however, to be greatly influenced by their mechanical condition ; for some of them, which are only slowly oxidized by expo- sure to air and heat, are rapidly acted upon when in very fine mechanical division, even at common temperatures. In combining with oxygen under heat, some of the metals burn with great splendour : this is exem- plified in copper, zinc, tin, and bismuth. Iron filings, when thrown even into the flame of a candle, and very fine iron wire, when held in the external part of the flame, take fire and throw off beautiful scin- tillations. Antimony burns at a white heat, and tellurium burns before the flame of the blow-pipe. In short, at intense heats most of the metals may be burned, and, if placed in the flame of the oxy- hydrogen blow-pipe, they deflagrate with intense brilliancy and great facility. On the other hand, potassium burns by contact with a piece of ice, with as much intensity as others do in the oxy-hydrogen flame. 3* 30 PROPERTIES OF THE METALS. The metals, by combination -with oxygen, lose their metallic characters, and form an important series of definite compounds known as the metallic oxides. These have very different characters and pro- perties ; even the same metal not unfrequently affords oxides which differ from each other widely in pro- perties and appearance. Thus fifty parts of mercury, combining with one part of oxygen, produces a black oxide, and with two parts of oxygen, the oxide is red and highly poisonous. Many of the metals thus afford more than one oxide ; and it is to be observed, that when the same metal unites in more than one proportion with oxygen, the oxygen in the second and higher oxides bears a definite arith- metical relation to the first ; and when two oxides are thus formed, that having the minimum of oxy- gen is termed the protoxide, and that with the maximum of oxygen the peroxide. This law of definite proportions will be explained hereafter. Among the combinations of metals with oxygen, some are soluble in water and alkaline, such as the fixed alkalies, soda, potash, and lithia, and the alkaline earths ; others are soluble and sour, form- ing the metallic acids. Some are insoluble in water, and have neither taste nor smell ; and many when TROrERTIES OF THE METALS. 31 taken into the stomach act as poisons. Thus, oxide of arsenic is a notorious and virulent poison ; oxide of copper is less virulent than arsenic ; oxide of lead is a painful poison ; oxide of nickel is also destructive of life ; and the peroxide of mercury, unless in small quantities, is likewise poisonous. 32 TROrERTIES OF THE METALS. ON METALLIC ALLOYS. The metals, for the most part, may be combined with each other, forming a most important class of compounds, known as the metallic alloys: Many of these are more useful than the metals of which they are composed, and possess properties a good deal different from their elements. One of the best known and most serviceable of all the alloys is brass, a compound of zinc and copper : it is harder, more easily melted, more close in the texture, better coloured, and less liable to tarnish than copper ; it is less brittle, and in every way more valuable than zinc. Pinchbeck is composed of the same ingre- dients as brass, but in different proportions, the zinc predominating. Copper and tin are two very soft and flexible metals, which, being fused together, form the alloy known as bell-metal, which is harder than iron, very brittle, and very sonorous. The same materials, in different proportions, form spe- culum metal, and the kind of ordnance improperly called brass cannon. Pewter is composed of tin and lead, sometimes with the addition of zinc, cop- per, or bismuth. ON METALLIC ALLOYS. 33 Plates upon which music is stamped are composed of tin and antimony ; and printing types are formed of an alloy of lead and antimony, with a slight ad- dition of bismuth. Tin-foil is an alloy of tin and lead ; and plumbers' solder is composed of the same metals. Fusible metal is a compound of bismuth, lead, and tin, with sometimes a little mercury. An amalgam of zinc and mercury is used for ex- citing electric machines, and that of mercury and tin is the compound employed for silvering looking- glasses. Gold coin is an alloy of gold and copper, in the proportion of 11 to 1 ; and jewellers' gold is an alloy of the same metals in the proportion of 3 of gold to 1 of copper. Green gold has silver instead of copper. Silver coin, in like manner, is an alloy of silver and copper in the proportion of 37 to 3. These alloys of gold and silver are harder, and consequently less liable to wear than the pure metals. It is worthy of remark, that in the formation of alloys, the metals in the act of combination gene- rally evolve heat. For instance, when platinum and tin-foil are fused together, there is the most vivid ignition ; and when zinc and copper are suddenly mixed, in the proportion to form brass, the increase of heat is such as to vaporize part of the metal. 34 PROPERTIES OF THE METALS. The alloys are formed by various processes, de- pending upon the nature of the metals employed. Most of them are prepared by simply fusing the two metals together ; but if there be a considerable difference in their specific gravities, the heavier very generally subsides, and the lower part of the mass thus differs in composition from the upper. This may be in a great measure prevented by agi- tating the alloy till it solidifies, but this is not always convenient. Thus, in stereotype plates which are cast vertically, the upper side usually contains more antimony than the other. The same is observed when an alloy of gold and copper is cast into bars ; the mould being placed perpendicularly, the upper part of the bar contains more copper than the lower. Copper and silver evince the same ten- dency to separate; although they appear readily to combine, it is found extremely difficult to form a bar of their alloy of perfectly uniform composition throughout. Many of the alloys, however, appear to be true chemical compounds ; and in some cases the metals unite in definite proportions only. It is indeed not improbable that wherever metals do form alloys, that the alloys so formed are definite compounds, and that any undue quantity of either metal present, simply mixes mechanically with the ON METALLIC ALLOYS. 35 mass. Thus, among the artificial as "well as natural alloys, there are many which crystallize ; and in some cases, the true compound may be separated from the mere mixture of the superfluous metal by the process of crystallization. The tendency of the metals to unite with other elements, and with each other, prevents their being often found disseminated in mineral nature, in their pure metallic state. Some of them do occur so nearly pure as to be called native metals. Thus gold is found only slightly alloyed with silver and copper, and pla- tinum occurs as an alloy of iron, palladium, iridium, rhodium, and osmium. Silver, copper, mercury, antimony, bismuth, arsenic, and tellurium, occur both in the native metallic state, although never absolutely pure, and mineralized with other bodies. Lead, tin, zinc, iron, antimony, and several others, are extensively disseminated as sulphurcts, that is, combined or mineralized by sulphur. The combination of a metal with its mineralizing substance, is what we denominate an ore; and it is in this state of ore that metals occur, when they are not found native. The ores are exceedingly diversified in appearance ; sometimes they possess metallic 36 PROPERTIES OF THE METALS. lustre ; sometimes they appear stony, at other times earthy. In some instances they are crystallized into regular forms, but more commonly they occur in shapeless masses. The ores are chiefly found in veins — that is, large fissures of rock, especially the granitic, schistous, and limestone rocks; but some- times they are found in rounded and detached frag- ments, disseminated through certain alluvial and diluvial strata of the earth. The extraction of the metal from them is denominated their reduction, and implies a laborious series of operations, me- chanical and chemical, comprehended under the term metallurgy. TABLE OF METALS. 37 The following table contains an enumeration of the metals, and may be useful for reference. The column headed "equivalents," shows the weight which unites with 8 oxygen to form the oxides, and the succeeding column contains the symbols by which the metals are denoted in systematic chemistry. Names of Metals. 1. Gold (Aurum) . . . .' 2. Silver (Argentum) . . . 3. Iron (Ferrum) .... 4. Copper (Cuprum) . . , 5. Mercury (Hydrargyrum) 6. Lead (Plumbum) . . . 7. Tiu (Starmum) . . . , 8. Antimony (Stibium) . . ' 9. Bismuth jlO. Zinc 111. Arsenic "| 12. Cobalt j 13. Platinum 14. Nickel 15. Manganese 16. Tungsten (Wolfram) . . 17. Tellurium 18. Molybdenum 19. Uranium 20. Titanium 21. Chromium 22. Columbium (Tantalum) . 23. Palladium , . . . . 24. Rhodium 25. Iridium 26. Osmium 27. Cerium 28. Potassium (Kalium) . 29. Sodium (Natronium) . 30. Barium 31. Strontium 32. Calcium 33. Cadmium 34. Lithium 35. Silicium 36. Zirconium . . . • . 37. Aluminum .... 38. Glucinum 39. Yttrium 40. Thorium 11. Magnesium .... 42. Vanadium 43. Lantanum Authors, and Dates of their Discovery. Known to the ancients. Basil Valentine 1490 Agricola . . 1530 Paracelsus? . 1530 Brandt Wood . . Cronstedt . Gahn . . D'Elhuiart Muller . . Hielm . . Klaproth . Gregor . . Vauquelin Hatchctt . Wollaston Tennant . Hisinger . 1733 1741 1751 1774 1781 1782 1782 1789 1791 1797 1S02 1803 1803 1804 Davy . . . 1S07 Stromeyer . 1818 Arfsvvedson . 1818 . 1824 . 1828 . 1829 . 1829 . 1830 . 1840 Berzelius . Wohler . Berzelius . Bussy . . Seftstrom . Mosander Specific Gravity. f 19.25 10.47 7.78 8.89 13.56 11.35 7.29 " 6.70 9.80 7.00 f 5.88 ( 8.53 20.98 8.27 6.85 17.60 6.11 7.40 9.00 5.30 11.50 0.86 0.97 8.60 Melting Points. Falir. 2016 3 1873 *2S00? 1996 —39 612 442 497 773 2810? oh. bp.f 2810? s. f. * 620? ohbp ohbp ohbp ohbp oh%p ohbp fohbp (ohbp 136 190 442 Equ. Hyd. = 1. 200 108 28 64 200 104 58 65 72 32 38 30 99 30 28 100 32 48 217 24 28 185 54 52 99 100 48 40 24 70 44 20 56 8 8 33 14 18 32 60 13 69 ? Syni, Au. Ag. Fe. Cu. Hg. Pb. Sn. Sb. Bi. Z. Ar. Co. PI. Ni. Mn. W. Te. Mo. U. Ti. Cr/ T. Pd. R. Ir. Os. Ce. K. Na. Ba. Sr. Ca. Cd. L. S. Zr. Al. Gl. Y. Th. Mg. V. Ln. Smith's forge. f Oxy-hydrogen blowpipe. 38 CONDUCTING TOWERS OF METALS. ON THE CONDUCTING POWERS OF VARIOUS METALS FOR VOLTAIC ELECTRICITY. The researches of Pouillet have thrown much light upon our knowledge of the conducting powers of various bodies for voltaic electricity, and the results he has arrived at enable him to express the relative conducting powers of the different metals by the following numbers : — Palladium 5791 Silver 5152 Gold . 3975 Copper . 3838 Platinum 855 Bismuth 38-1 Brass from 900 to 200 Cast steel from 800 to 500 Iron 600 Mercury 100 The resistance of metals to conduction of electri- city has been accurately ascertained by means of the degrees of heat evolved by the passage of a current of equal intensity through different metals ; CONDUCTING POWERS OF METALS. 39 the heat developed in conducting wires is in propor- tion to the extent of surface of the positive plate, no matter whether the current emanate from a sin- gle cell or a series of cells. The following table shows the degrees of heat evolved by an equal cur- rent from different metals, measured by the pressure of expanded air upon a column of alcohol : Metals. Heat Evolved. Resistance. Silver .... 6 1 Copper .... 6 1 Gold .... 9 n Zinc .... 18 3 Platinum 30 5 Iron ..... 30 5 Tin ... 36 6 Lead .... 72 12 Brass .... 18 3 It is apparent that the conducting powers of the above metals are inversely as these numbers. Sil- ver being a better conductor than lead, in the ratio of 12 to 1. (40) O J d a" -■ S js E £ 5 £ P S s S s 3 o -o •ll •aonasaad •aatiosa.ul .naq} -ipqj oi noq.u. in noq.u "jajE^ i!og 'jajB^y. Eas n ! noaj m noaj isbq jo uoisoj-ioo ?sbq jo notsoaaog aq:> aqt asBaaon; sionv asaqj nV asuojoap s.Co[iv asaqi HV e — 53 »"*■ gd S l. C as 3 " ~ c S9«>2 C 5 S r, ft H _■ — o5 j§ pq t/j -^ ~£ -2 «5 ^ « h « SJ ?3 *" r. 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ON FOUNDING. The general object of founding is, to mould iron, copper, tin, zinc, lead, &c, &c, in a melted state into the various forms required for the parts of machines and other constructions. Wrought iron and steel cannot be properly melted by heat. At high temperatures they drop away and spark off, while the main body of the metal main- tains its consistency, and it undergoes rapid oxida- tion, as is shown by the scales which are perpetually formed on its surface. These metals are, however, in this condition ren- dered extremely ductile, and the wrought iron espe- cially may be fashioned with facility into any required form, by the application of the hammer. On the contrary, pig iron, of which wrought iron and steel are preparations, has peculiarly the pro- perty of liquefaction by heat, and is therefore well adapted as a material for castings, in which strength and hardness are required. The business of the founder is therefore to take advantage of the common law, according to which fluids always find their level. If, for example, a quantity of water be poured into a vessel, however ON FOUNDING. 43 curiously shaped, it first finds the bottom, and then spreads on all sides as it rises, filling every corner it can reach. The body of water must then be a perfect model in form of the interior of the vessel, and this may be seen by solidifying it in its place by the application of cold, and extracting the body of ice. To mould a quantity of melted metal into a desired form, two things are therefore necessary : first, a model, or pattern of the required form. Secondly, a substance of sufficient susceptibility and adhesiveness to receive accurately, and to retain impressions of that pattern made upon it, against the violence of the liquid metal, when run into the mould which is thereby formed. ON BRASS FOUNDING. Brass founding, considered as a branch of engi- neering, is beset with a host of empirical rules and fancies, to an extent which natur.ally surprises the scientific practician, when he considers it with regard to the present calculating and philosophizing age. 44 ON BRASS FOUNDING. Every founder thinks lie possesses the only true and orthodox system of producing first-rate castings, and, as a matter of course, every one differs from his neighbour in his routine of practice, without reflecting that the process admits as fully of a reduc- tion to scientific rules as any of its sister branches of the manipulatory art. It is scarcely necessary to observe, that excellence can never be attained in any art in the prosecution of which so loose a system is tolerated : guess-work will ever give chance results, productive only of inconveniences and objections, which a more system- atic code of regulations would entirely obviate. The number of alloys of copper which come under the generic name of brass, as has been shown, amount to a numerous family, and are of the greatest im- portance, not only to the engineer, but to artists generally, involving the use of the following differ- ent metals, all of which are required in a greater or less degree to suit the variety of operations where brass is indispensable : namely, copper, tin, lead, zinc, antimony, and, in some cases, nickel. The first four of these metals are those in the greatest request for engineering purposes. The leading metal of this series, copper, was known to the ancients previous to the discovery of malleable ON COPPER. 45 iron, and was applied to all the purposes for which the latter metal alone is now used. Although we find brass frequently spoken of in the Scriptures, as well as in many portions of pro- fane history, yet it is a well ascertained fact that this refers to copper ; the brass of the present day being a discovery of much later date. COPPER. The word copper is derived from the Island of Cyprus, where it was first wrought by the Greeks. The best method of obtaining it pure, where extreme purity is an object of importance, is to dissolve it in nitric acid : the solution is then diluted, and a piece of iron introduced, upon which the pure metal is precipitated, any adherent particles of iron being readily removed by washing with dilute sulphuric acid. Another method has lately been discovered of purifying copper, namely, by melting 100 parts of it, with 10 parts of copper scales (black oxide), along with 10 parts of ground bottle-glass, or other flux. Mr. Lewis Thompson, who received a gold 46 ON THE REDUCTION OF COPPER. medal from the Society of Arts, for this invention, says that, after the copper has been kept in fusion for half an hour, it will be found at the bottom of the crucible, perfectly pure, while the iron, lead, arsenic, &c, &c, with which this metal is usually contaminated, will be oxidized by the scales, and will dissolve in the flux, or be volatilized. Thus he has obtained perfectly pure copper from brass, bell- metal, gun-metal, and several other alloys, contain- ing from 4 up to 50 per cent, of iron, lead, bismuth, antimony, arsenic, &e. The scales of copper are cheap, being the product of every large manufac- tory. Copper melts at a white heat, and by slow cooling may be crystallized. Its specific gravity is 9, nearly. It melts at a temperature of 1996° Eahr. On the Reduction of Copper. The reduction of copper ore is made by several consecutive processes. The first is by calcining it, and, when the ore is sufficiently " roasted" to oxi- date the iron which it contains, it is melted. The melted metal is, after a time, suffered to flow into a pit filled with water, by which it becomes granu- lated. ON TIN. 47 It then undergoes further heating, and "what is called technically its slag (or scoria) is taken off, and it is allowed again to run off into water. After these processes it is cast in sand, when it becomes solid, and in this state is called "blistered copper." It is now fit for what is called the refinery, and undergoes an operation called refining, or toughen- ing. This is considered to be an operation of deli- cacy, and requires great skill and care in the work- men. It is conducted to a furnace similar to the melting furnace, and the object is to thoroughly purify the metal from any portions of oxygen, which is performed by adding charcoal to the copper, while it is in fusion, and stirring it occasionally, till it is judged to be pure. TIN, OR BEDIL IN THE HEBREW. The next metal on our list has also been known from the remotest ages. It is mentioned by Eleazar the priest in the book of Numbers, chapter 81st, verse 2 2d. All the other metals supposed to have 48 ON TIN. been then known arc enumerated in the same pas- sage. Thus, lexicographers form bedil, " to sepa- rate," tin being a separating metal. This carries the knowledge and use of tin back 1500 years antecedent to the commencement of our era. The Phoenicians used tin, of course, m the erection and decoration of the Temple of Solomon. Their brass was bronze ; zinc had not then been discovered. We read of tin, also, having been got by the Cartha- ginian navigator, Himiles, from the Scilly Islands ; they certainly present appearances of ancient exca- vations. Tin occurs, native, in two forms — as per- oxide, and as sulphuret of tin and copper. The last is rare ; the former constitutes the great source of tin, and, in its native mixed state with arsenic, cop- per, zinc, and tungsten, is called "tin-stone;" but, when occurring in rounded masses, grains, or sand in alluvial soil, is called stream tin. The metal reduced from the tin-stone forms block tin — that from the stream tin forms grain tin. The greater part of the East Indian tin comes from Siam, Malacca, and Banca. The last place is an island near the south-east coast of Sumatra. The mines were discovered in 1711 ; in 1T7G there were ten pits which were worked by the Chinese on account of the King of Talimbang. One hundred REDUCTION OF GRAIN AND BLOCK TIN. 49 and twenty-five pounds cost him only five rix dol- lars. The greater part went to Alinia, or was used in India. On the Reductioyi of Tin, Grain, and Block Tin. The best ore of tin is found in Cornwall ; it is commonly blasted by gunpowder, and is procured in pieces of considerable size, which are stamped, by beams shod with iron, to powder. It is then well washed, till the earthy particles are carried off, and the tin is fit for the smelting-house. After being roasted in a reverberatory furnace, and again washed, it is a second time subjected to the furnace, being now mixed with small coal and, in some cases, with a small quantity of lime. The melted tin thus produced is at last placed in a small furnace, and exposed to a very gentle heat, when the purest portion melts first, and is drawn off. This is called " common grain tin." And the inferior, which still contains a small proportion of copper and arsenic, is then cast into pigs, called "block tin." The purest tin is procured from the stream works of Cornwall, and affords from 65 to 75 per cent, of the best grain tin ; its specific gravity is about 7.5 ; 50 OF ZINC. it melts at a temperature of 442°. Like copper, it is the nucleus of an immense number of subsidiary metals, which it is our intention shortly to enter upon. ZINC. Zinc is a metal whose extensive range of appli- cation is only now beginning to be understood. It is found in the state of oxide and sulphuret ; its specific gravity is about 7.7 ; its fusing point is 773°, but at a temperature of 300°, it becomes extremely malleable, and may be rolled into thin leaves, or drawn into fine wire. One of its most valuable modern applications, is as a protective covering for iron, being the best known substance for this purpose. The purifying of zinc may be eifected by melting the impure metal with lead, in equal parts, in a deep iron pot, stirring them well together, skimming off the impurities as they rise, covering the surface with charcoal to prevent oxi- dation, and keeping them in a fused state for three hours. The lead descends to the bottom by its greater density, and leaves the zinc above, to be ON LEAD. 51 drawn off by a pipe in the side of the melting-pot. This contrivance is the subject of a patent, granted to Mr. William Godfrey Kneller, in 1844. LEAD. Lead was also known to the ancients. Its specific gravity is 11.4 ; melts at a temperature of 612°. This metal is highly poisonous, and the greatest amount of caution ought to be observed in its appli- cation to domestic purposes, as, when in contact with water in open vessels, it quickly tarnishes, and small crystalline scales of oxide of lead are formed, a portion of which dissolves in the water, and is again precipitated in the form of a carbonate. If, however, the water contains a very slight amount of sulphuric acid, or a soluble sulphate, the corro- sion is prevented. 52 ON ANTIMONY. ANTIMONY. Antimony was discovered by Basil Valentine (a monk), in the fifteenth century. It is of a grayish- white, having a slight bluish shade, and very bril- liant. Its texture is lamellated, and exhibits plates crossing each other in every direction. Its surface is covered with herbarizations and foliage. Its spe- cific gravity is 6.702. It is sufficiently hard to scratch all the soft metals ; it is Very brittle, easily broken, and pulverizable. It fuses at 810° Fahr. ; it can be volatilized, and burns by a strong heat. When perfectly fused and suffered to cool gradually, it crystallizes in octahedra. It unites with sulphur and phosphorus. It decomposes water strongly. It is soluble in alkaline sulphates; sulphuric acid boiled upon antimony, is feebly decomposed. Nitric acid dissolves it in the cold ; muriatic acid scarcely acts upon it. The oxygenated muriatic gas inflames it, and the liquid acid dissolves it with facility. Arsenic acid dissolves it by heat with difficulty. It unites by fusion with gold, and renders it pale and brittle. Platina, silver, lead, bismuth, nickel, cop- per, arsenic, iron, cobalt, tin, and zinc unite with ORDER AND WORKING OF METALS. 53 antimony by fusion, and form with it compounds more or less brittle. Mercury does not alloy with it easily. We are little acquainted with the action of alkalies upon it. Nitrate of potash is decomposed by it. It fulminates by percussion with oxygenated muriate of potash. The order and facility of working these metals vary considerably with the purpose to which they are applied. Thus, regarding their wire-drawing ductibility, gold is the most ductile metal, being 1. The four first metals are as follows : copper 5, zinc 6, tin 7, lead 8. Their relative values as laminable substances are considerably different : thus, under the same circumstances, copper is 3, tin 4, lead 6, zinc 7. The following tabulated statements exhibit the most approved properties of the most useful class of alloys, as laid down by the best authorities, to- gether with the specific purposes to which they are adapted. The first we shall treat upon are the alloys of copper and tin. In this table the quantity of tin is that which is added to one pound of copper. 5* 54 ON COrPER AND TIN. COPPER AND TIN. 1 ounce. Soft gun metal. li " X Z A slightly harder alloy, fit for ma- thematical instruments. li " Still harder, fit for wheels. 11 to 2 " Brass guns. 2 to 2J " Hard bearings for machinery. 3 " Musical bells. H " Chinese gongs, cymbals, &c. 4 " Small house bells for domestic pur- poses. 4i « Large do. 5 " Largest bells, for churches, &c. 7 to 8 " Speculum metal for the reflectors of telescopes, light-houses, &c. Temper, is a mixture of 2 pounds of tin to 1 pound of copper, and is used for adding to tin in the manufacture of pewter ; the object being to intro- duce an extremely small quantity of copper. ON BRONZE AND BELL METAL. 55 BRONZE FOR CANNON, STATUES, ETC. Bronze is an alloy of copper, with from 8 to 10 per cent, of tin, together with small quantities of other metals, which are not essential to the com- pound. Cannons are cast with an alloy of a similar kind, and the ancient bronze statues were of the same composition. ON BELL METAL. Bell metal is a compound of 80 parts copper to 20 parts tin. The Indian gong, so much celebrated for the richness of its tones, contains copper and tin, in the above proportions. The proportion of tin in bell metal varies, however, from one-third to one- fifth of the weight of copper, according to the sound required, the size of the bell, and the impulse to be given. M. de Arcet has discovered that bell metals formed in the proportion of 78 parts copper, united with 22 of tin, is indeed nearly as brittle as glass, when cast in a thin plate or gong. Yet if it be 56 ON COPPER AND TIN MIXTURES. heated to a cherry-red, and plunged into cold water, being held between two plates of iron, that the plate may not bend, it becomes malleable. Thus he manufactures gongs, cymbals, and tantums out of this compound. ON COPPER AND TIN MIXTURES. The above are the best proportions in use at the present day; for some other peculiar objects a slightly different mixture is adopted, as a small amount of zinc or silver, and even arsenic. The best mode of mixing the component metals of this alloy, appears to be to melt each separately, and then to add the tin to the copper at the lowest stir- ring temperature. To complete the combination the alloy is again melted very gradually by placing the metal in the crucible almost as soon as the fire is lighted. The hardness of this alloy, compared with the extreme softness of the metals, gives us an example of the chemical changes effected by their combination. Thus, the speculum metal, as used by Lord Rosse, is totally devoid of malleability, and from its hardness cannot be acted on by the file. SPECULUM, COPPER, AND ZINC. 57 His speculum consisted of four atoms of chemical combining proportions of copper to one of tin : or, by weight, 126.4 copper to 58.9 tin. This alloy, which is a true chemical compound, is of a brilliant white lustre; its specific gravity 8.811; nearly as hard as steel, and almost as brittle as sealing-wax. The speculum is six feet in diameter, five and a half inches thick. It was cast open, ground with emery, placed on a table in a cistern filled with water at a temperature of 55° Fahr., polished with red oxide of iron, procured by precipitation from green vitriol, or sulphate of iron, by water of ammonia. ALLOYS OF COPPER AND ZINC. We now come to the consideration of another branch of the copper alloy family of great value in the arts. This is copper and zinc. The following table contains the best proportions of the principal mixtures. In this table the quan- tity of zinc is that which is added to one pound of copper. 58 ALLOYS OF COPPER AND ZINC. to | tolj 2 to 4 5 6 7 to7| 8 10* 14 16 ounce. This addition is used principally for the purpose of producing sound copper castings. Gilding metal for jewellers. Tombac, or red brass. Red sheet brass, pinchbeck, and bath metal. Purbeck metal. Bristol brass. This and the five preceding mixtures solder well. Good dipping metal. The general proportion for all or- dinary brass articles. Muntz's metal, for ships' fasten- ings, sheathing, &c. Strong brazing solder, for heavy copper work, &c. Soft spelter solder. From the volatile nature of zinc the above pro- portions can seldom be strictly adhered to ; but a slight variation does not much affect the filing and working of the metal. An alloy of copper and lead is often used in place of gun metal for inferior work, on account of its ON COPPER, ZINC, TIN, AND LEAD. 59 cheapness and facility of manipulation. It is very brittle, particularly where much lead is used. The whole of the different metals just discussed, when mixed together, constitute gun metal, or brass, par excellence. This alloy is applied to a very great variety of purposes, and is the one most in demand for engineering works. The principal ones are compounded as below. ALLOYS OE COPPER, ZINC, TIN, AND LEAD. 1 j ounces tin, J ounce zinc, and 16 ounces copper, constitute an extremely tenacious metal, used where great strength is required. 1 J ounces tin, 2 ounces brass, 16 ounces copper, for wheels, &c. 2 ounces tin, 1J ounces brass, 16 ounces copper, for articles requiring turning. 2i ounces tin, 1J ounces brass, 16 ounces copper, for bearings, nuts, &c. 1J ounces tin, 1J ounces zinc, 16 ounces copper, a composition for general purposes, used by an emi- nent engineer. 60 ALLOYS. 2J ounces tin, J- ounce zinc, 16 ounces copper, for bearings to resist great strains. 2J- ounces tin, 2J ounces zinc, 16 ounces copper, an extremely hard metal, almost too hard for the file. 1 ounce tin, 2 ounces zinc, 16 ounces copper, good button metal. 5 pounds of zinc to 8 pounds of brass (called pla- tina), an extremely pale, nearly white metal, used by Birmingham button-makers. 9 pounds of zinc to 32 pounds of brass, another alloy, called Bath metal. 10 pounds of tin, 6 pounds of copper, 4 pounds of brass, constitute white solder. 14.75 tin, 144 copper, and 12 brass, is the alloy of the English standard measure. Manheim Gold. — 3 parts copper, 1 part zinc, and a small quantity of tin. If these metals are pure, and melted in a covered crucible, contain- ing charcoal, the alloy bears so close a resemblance to gold as to deceive very skilful persons. Best Pinchbeck, 5 ounces pure copper, and 1 of zinc. ALLOYS. 61 Princess Metal. — 3 parts copper, 1 part common brass, and J ounce zinc. 5J pounds copper, J- pound zinc, best Tombac, beautifully red, and is more durable than copper. Artificial Gold. — 16 parts virgin platina, 7 parts copper, 1 part zinc, put in a crucible, covered with powdered charcoal, and melted till the whole forms one mass. Fine Brazing Solder. — 12 pounds of copper, 11 pounds of zinc, flux with powdered brimstone. We might multiply these examples of the differ- ent mixtures, but as we have already extended this portion of our article to a considerable length, and have given what appear to be the best for general purposes, we shall defer any further remarks on the subject, until we come to white metals, receipts, &c, at the latter part of the work. 6 62 REMARKS. Having discussed the rationale of the mixture and proportion of the metals used in alloys of cop- per, the matter leads us to the further consideration of casting them. Brass moulding is carried on by means of earthen, or sand moulds. The formation of sand moulds is by no means so simple an affair as it would at first sight appear to be, as it requires long practical experience to overcome the disadvan- tages attendant upon the material used. The moulds must be sufficiently strong to withstand the action of the fluid metal perfectly, and, at the same time, must be so far pervious to the air as to permit of the egress of the gases formed by the action of the metal on the sand. If the material were perfectly air-tight, then damage would ensue frqm the pres- sure arising from the rapidity of the generation of the gases, which would spoil the effect of the casting, and probably do serious injury to the operator. If the gases are locked up within the mould, the general result is what moulders term a blown cast- ing ; that is, its surface becomes filled with bubbles of air, rendering its texture porous and weak, besides injuring its appearance. Plaster of Paris is often used for a number of the FACING. 63 more fusible metals. This material, however, will not answer for the more refractory ones, as the heat causes it to crumble away and lose its shape. Sand, mixed with clay or loam, possesses advan- tages not to be found in gypsum, and is consequently used in place of it, for brass and other alloys. In the formation of brass moulds, old damp sand is principally used in preference to the fresh material, being much less adhesive, and allowing the patterns to leave the moulds easier and cleaner. Meal dust or flour is used for facing the moulds of small articles ; but for larger works, powdered chalk, wood-ashes, &c, are used, as being more eco- nomical. If particularly fine work is required, & facing of charcoal or rottenstone is applied. Another plan for giving a fine surface is to dry the moulds over a slow fire of cork shavings, or other carbonaceous substance, which deposits a fine thin coating of car- bon. This, when good fine facing-sand is not to be obtained. As regards the proportions of sand and loam used in the formation of the moulds, it is to be remarked, that the greater the quantity of the former material, the more easily will the gases escape, and the less 64 METALLIC MOULDS. likelihood is there of a failure of the casting ; on the other hand, if the latter substance predominates, the impression of the pattern will be better, but a far greater liability of injury to the casting will be incurred from the impermeable nature of the mould- ing material. This however may be got over with- out the slightest risk, by well drying the mould prior to casting, as you would have to do were the mould entirely of loam. For some works, where easily fusible metal is used, metallic moulds are adopted. Thus, where great quantities of one particular species of casting is required, the metallic mould is cheaper, easier of management, and possesses the advantage of pro- ducing any number of exactly similar copies. The simplest example which we can adduce is the cast- ing of bullets. These are cast in moulds constructed like scissors, or pliers, the jaws or nipping portions being each hollowed out hemispherically, so that when closed a complete hollow sphere is formed, having a small aperture leading into the centre of the division line, by which the molten lead is poured in. Pewter pots, inkstands, printing types, and va- rious other articles, composed of the easily fusible metals, or their compounds, are moulded on the PEWTERING. 65 same principle. The pewterer generally uses brass moulds : they are heated previous to pouring in the metal. In order to cause the casting to leave the mould easier, as well as to give a finer face to the article, the mould is brushed thinly over with red ochre and white of an egg ; in some cases, a thin film of oil is used instead. Many of the moulds for this purpose are extremely complex, and, being made in several pieces, they require great care in fitting. With these peculiar cases we have, at present, little to do, and shall conclude with a few observa- tions on the method of filling the moulds. The experienced find that the proper time for pouring the metal is indicated by the wasting of the zinc, which gives off a lambent flame from the surface of the melted metal. The moment this is observed, the crucible is to be removed from the fire, in order to avoid incurring a great waste of this volatile sub- stance. The metal is then to be immediately poured. The best temperature for pouring, is that at which it will take the sharpest impression and yet cool quickly. If the metal is very hot, and remains long in contact with the mould, what is called sand-burn- ing takes place, and the face of the casting is in- jured. 6* 66 COMPLEX OBJECTS. The founder, then, must rely on his own judgment, as to what is the lowest heat at which good, sharp impressions will be produced. As a rule, the smallest and thinnest castings must be cast the first in a pouring, as the metal cools quickest in such cases, while the reverse holds good with regard to larger ones. Complex objects, when inflammable, are occasion- ally moulded in brass, and some other of the fusible metals, by an extremely ingenious process ; render- ing what otherwise would be a difficult problem a comparatively easy matter. The mould, which it must be understood is to be composed of some inflammable material, is to be placed in the sand-flask, and the moulding sand filled in gradually until the box is filled up. When dry, the whole is placed in an oven sufficiently hot to reduce the mould to ashes, which are easily re- moved from their hollow, when the metal may be poured in. In this way (as will be afterwards shown) small animals, birds, or vegetables may be cast with the greatest facility. The animal is to be placed in the empty moulding- box, being held in the exact position required, by suitable wires or strings, which may be burnt or removed, previous to pouring in the metal. ON BELL FOUNDING. 67 Another mode which appears to be founded on the same principle, answers perfectly well when the original model is moulded in wax. The model is placed in the moulding-box in the manner detailed in the last process, having an additional piece of wax to represent the runner for the metal. The composition here used for moulding is similar to that employed by statue founders in forming the cores for statues, busts, &c, namely, two parts brick-dust to one of plaster of Paris. This is mixed with water and poured in so as to surround the model well. The whole is then slowly dried, and when the mould is sufficiently hardened to withstand the effects of the molten wax, it is warmed, in order to liquify and pour it out. When clear of the wax, the mould is dried and buried in sand, in order to sustain it against the action of the fluid metal. If our limits permitted, we might mention the de- tails of numerous other works in the founding of brass. We must for the present content ourselves with a brief examination of one or two cases which come more or less within the province of the engi- neer. One of these is the founding of bells, a sub- ject of considerable interest, as works of this kind are often of very considerable magnitude, and de- mand the skilful attention of the engineer. Large 68 ON GUN FOUNDING. bells are usually cast in loam moulds, being swept up, according to the founder's phraseology, by means of wooden or metal patterns, 'whose contour is an exact representation of the inner and outer surfaces of the intended bell. Sometimes, indeed, the whole exterior of the bell is moulded in wax, which serves as a model to form the impression in the sand, the wax being melted out previous to pouring in the metal. This plan is rarely pursued, and is only feasible when the casting is small. The inscriptions, ornaments, scrolls, &c, usually found on bells, are put on the clay mould separately, being moulded in wax or clay, and stuck on while soft. The same plan is pursued with regard to the ears, or supporting lugs, by which the bell is hung. BRASS GUNS Are another important branch of this manufac- ture. They are moulded in a manner quite distinct from any other work of this nature. The exterior surface of the gun is produced by wrapping gaskin or soft rope round a tapered rod, of a length slightly ON GUN FOUNDING. 69 greater than that of the gun. Upon this foundation of rope the moulding loam is then applied ; the surface being turned to the exact shape and propor- tions of the gun. A long fire is used by the founder in this process, in order to dry the mould as he proceeds in its manufacture. When perfectly dry, the surface of the mould is black-washed over, and again covered ■with loam to a depth of two or three inches. This exterior coat of loam is secured and strengthened by a number of iron bands, and the whole is well dried. The primary mould is now completely with- drawn from the outer shell, the formation of which renders it an easy matter, as the timber rod leaves the rope with great facility, when the latter may be withdrawn, and the clay covering picked out afterwards. The trunnions of the gun are formed separately, and attached to the shell in the ordinary way. When finished, the moulds are sunk perpendicu- larly in a sand pit, near a reverberatory furnace, a vertical runner being made, leading to each mould, which it enters near the bottom. A suitable chan- nel communicates with the furnace containing the brass intended for the guns. The metal being in- 70 ON FIGURE CASTING. troduced at the bottom of the mould, no air can possibly be detained by its entrance, as each mould is full open to the atmosphere at the top. FIGURE CASTING Is another branch of our subject, and one which, from its general complexity, ranks as the greatest effort of the founder. As an example of this pro- cess we shall take the moulding of thin ornaments in relief. The ornament, whatever it may be, a monumental bas-relief for instance, is first modelled in relief, in clay or wax, upon a flat surface. A sand flask is then placed upon the board, over the model, and well rammed with sand, which thus takes the im- press of the model on its lower surface. A second flask is now laid on the sunken impression, and also filled with sand, in order to take the relief impres- sion from it. This is generally termed the cope, or back mould. The thickness of the intended cast is then determined by placing an edging of clay round the lower flask, upon which edging the upper one rests, thus keeping the two surfaces at the precise ON FIGURE CASTING. 71 distance from each other, that it is intended the thickness of the casting shall be. In this process, the metal is economised to the greatest possible extent, as the interior surface, or back of the casting, is an exact representation of the relief of the subject ; and the whole is thus made as thin in every part as the strength of the metal permits. Several modifications of the process just described are also made use of, to suit the particular circum- stances of the case. What we have said, however, is a detail of the principle pursued in all matters of a similar nature. In conclusion we will give a com- position for cores that may be required for difficult jobs, where it would be extremely expensive to make a core-box for the same : — Make a pattern (of any material that will stand moulding from) like unto the core required. Take a mould from the same in the sand, in the ordinary way ; place strengthening wires from point to point, centrally ; gate and close your flask. Then make a composition of two parts brick-dust and one part plaster of Paris ; mix with water and cast. Take it out when set, dry it, and place it in your mould warm, so that there may be no cold air in it. 72 BRASS MIRRORS, ETC. BRASS MIRRORS.* An Etruscan mirror, placed in the hands of " Gerharht of Berlin," was found to consist, in 100 parts, of 67.12 copper, 24.93 tin, 8.13 lead ; ap- proximating closely to an alloy of 8 parts copper, 3 of tin, and 1 of lead. The oxide of tin obtained in the course of analysis was carefully examined before the blow-pipe for antimony, but he saw no trace of that metal. A similar mirror has been analysed by " Klap- roth." He found 62 per cent, copper, 32 tin, and 6 per cent. lead. Copper. — Copper is thick and pasty, and without some alloy will not run into the cavities and sinu- osities of the mould. Metals, — A quarter of a grain of lead will render an ounce of gold perfectly brittle, although neither gold or lead are brittle metals. * See Job, xxxvii. 18; Exodus, xxxviii. 8. SURFACE OF METALS, ETC. 73 Surface of Metals. — The surface of metals should be carefully defended, while in the fluid state, from the action of the atmosphere, by a stratum of wax, pitch, or resin, if the fusing point be low ; or by a layer of salt, powdered glass, borax, charcoal, &c., if it is high. Blanched Copper. — 8 ounces of copper, and J an ounce of neutral arsenical salt, fused together under a flux of calcined borax and pounded glass, to which charcoal powder is added, makes blanched copper. British Weapons and Tools in Bronze, anciently called Corinthian and Syracuse Brass. — The metal of which the British weapons and tools were made, has been chemically analysed in modern times, and the proportions appear to be — In a spear head, 1 part of tin to 6 parts of copper. In an axe head, 1 do. 10 do. In a knife, 1 do. 7J do. 74 ON BRASS. ON BRASS. In Germany brass appears to have been made for centuries before the manufacture was introduced into England. This is stated to have been done by a German, who worked at Esher, in Surrey, in the year 1649. The analysis of a few pieces of bronze, of undoubted antiquity, namely, a helmet with an inscription (found at Delphi, and now in the British Museum), some nails from the treasury of Atreus, at Mycenae, an ancient Corinthian coin, and a por- tion of a breast-plate, or cuirass, of exquisite work- manship (also in the British Museum), affords about 87 to 88 parts copper to about 12 to 13 tin, per cent. The experiments of Klaproth and others give nearly the same results as to ingredients ; the quan- tities sometimes slightly differ. Lead is contained in some specimens, as has been shown. Zinc, and the nature of it, as heretofore observed, was not known to the ancients. In an antique sword, found many years ago, in CASTING IN PLASTER. 75 France, the proportions in 100 parts were, 87.47 copper, 12.53 tin, with a small portion of lead, not worth noticing. METHOD OF CASTING IN PLASTER — MEDALLIONS, ETC. Obtain some fine plaster, of good colour, and pass it through a muslin sieve, to remove any coarser particles which may be present. By mixing gum arable with the water intended to he used in the plaster, not only will the plaster be rendered very hard when it sets, but a beautiful gloss will be given to the surface. Care must be taken to drop the plaster powder gradually into the water, and to per- mit the bubbles to rise before the mixture is stirred ; otherwise it will become lumpy. The plaster should be of the consistence of the yolk of an egg, and, of course, used immediately. If the medal intended to be copied is a valuable one, with a smooth surface, it will be advisable not to oil it, as, in cleaning the oil off, the polish may be injured; but if the surface be rough there will be no remedy, and the oil must afterwards be removed, by dabbing the sur- face of the medal gently with a soft cloth. 76 CASTING IN PLASTER. A rim of thin lead, brass, copper, or even oiled paper, is then tied round the medal, and some liquid plaster, in the first place, stippled over its surface with a soft brush, to prevent the formation of air bubbles, as well as to insure its insertion into the most minute crevices; after which the plaster is poured upon the surface to the thickness of half an inch, or an inch if a large medal. To separate the mould from the medal, all we have to do is to immerse it in water, when it is readily removed ; otherwise the mould is sure to be broken. To obtain a plaster cast from this mould, we must oil it with warm boiled linseed oil, and allow it seve- ral days to dry. Whenever the mould is used it must be well oiled; otherwise the surface of the casting will be destroyed. The best olive oil must be used, or the colour of the plaster will be injured. TRANSFERRING AND VARNISHING. 77 TO TRANSFER ENGRAVINGS TO PLASTER CASTS. Cover the plate with ink, and polish its surface in the usual way ; then put your rim round it, as before stated, and pour in your plaster, mixed as before. Jerk the plate repeatedly, to allow the air bubbles to fly upwards, and let it stand one hour ; then take the cast off the plate, and a very perfect impression will be the result. TO VARNISH PLASTER CASTS. Plaster casts are varnished by a mixture of soap and white wax in boiling water. A quarter of an ounce of soap is dissolved in a pint of water, and an equal quantity of wax afterwards incorporated. The cast is dipped in this liquid, and, after drying a week, is polished, by rubbing with soft linen, pro- ducing a polish like marble. If to be exposed to the weather, saturate them with linseed oil mixed 7 * 78 CONCAVE AND CONVEX MOULDS. with wax, or rosin may be combined. In casting the plaster, always use spring water and gum arabic. TO CAST CONCAVE OR CONVEX MOULDS OF MEDALS, ON "TIN-EOIL," WITH PLASTER. Take a medal, &c, and cover it with very thin " tin-foil," which press as close to the medal as you can ; go over every part with a brush, laying on tolerably hard, in order to press the tin-foil into every cavity of the medal. After which, you may pour plaster upon it, and, when it is hard, take the medal out, leaving the tin-foil in the plaster ; then, with a little fine olive oil, anoint the tin-foil, and the plaster where it must part, and pour more plas- ter upon the tin-foil, which also let harden. You may then separate them, and take out the tin-foil, and you will have both a concave and a convex mould. CASTING COMPLEX OBJECTS. 79 TO CAST VEGETABLES, INSECTS, SMALL BIRDS, FROGS, EISH, ETC., IN PLASTER MOULDS. Provide a trough of boards, nailed together so as not to let the water run through the joints. Sus- pend in the trough, by thread or Holland twine, in several places, the vegetable, plant, insect, &c, which you would cast, which being performed, mix four parts of plaster of Paris, and two parts of fine brick-dust, with common water, to the consistence of cream, and with this cover the thing intended to be cast, observing not to distort it, by any means, from its natural position. When you have filled your trough, let it harden by placing it near the fire by degrees till you can make it red hot. Then let it cool, and, with a pair of bellows, blow and shake as much of the ashes out of the mould as you can. You must now put a small quantity of quicksilver into the mould, and shake it, in order to loosen every part of the ashes therein ; also to make a passage through where the strings were tied, in order to let the air out when you pour in your metal. 80 FUSIBLE METALS. TO PREPARE A METAL FOR THE ABOVE WORK. Take of grain tin 6 ounces, bismuth 2 ounces, and lead 3 ounces. Melt them together in an iron ladle, and you may cast in the above mould to your satisfaction. You may combine the above ingredients in such proportions as to compose a metal that will melt in boiling water. Thus, Sir Isaac Newton s Fusible Metal is composed of 8 parts bismuth, 5 parts lead, and 3 parts tin. This alloy melts at 212°. Hose's Alloy is still more fusible : it is 2 parts bismuth, 1 lead, and 1 tin, and melts at 201°. The late Dr. Daltons Fusible Alloy. — 3 parts tin, 5 parts lead, and 10J parts bismuth ; melts at 197°. The addition of a little mercury makes it more fusible, and fits it to be used as a coating to the insides of glass globes. CASTING IN WAX. 81 An alloy of equal parts of tin and bismuth melts at 280°. A less proportion of bismuth adds to the hardness of tin, and hence its use in the formation of pewter, or pewter solder. TO CAST IN WAX. The mould is first made in plaster, but before being used it is placed in warm water, of which it is allowed to absorb as much as it will take — oil not being used in this process. The surface must then be allowed to dry, or the wax would not adhere closely. Pure wax is too greasy for the purpose, and bladder flake-ivhite is therefore mixed with it ; the quantity cannot be stated ; but the addition of too much gives wax the appearance of plaster, by taking away its richness. The oftener the wax is remelted, the more its colour is injured. In order to obtain a gray marble colour, a marble powder, procurable at any statuary, is mixed with the wax, which not only gives a beautiful appearance to it, but renders it more durable. The wax is poured into the mould and allowed to 62 ' CASTING IN SULPHUR. flow over its surface, and by moistening the plaster mould in water when the wax has become hard, the cast is easily removed. Wax models may be fastened by means of linseed oil and flake-white, and also by a combination of bees' wax and resin. TO CAST IN SULPHUR. This is a very permanent mode, but as a mould it can only be used for plaster ; for hot wax or sul- phur would injure its surface. When sulphur is heated to the temperature suitable for forming casts, it becomes nearly black, and has, therefore, to be coloured in the proportion of one ounce of Vermil- lion to three ounces of sulphur. The surface of the mould, however, need only be coated with this expensive mixture, and common sulphur in any quantity. You must use wood to stir the sulphur, as iron will take away its colour. The sulphur will take fire in melting, unless it is properly stirred, and at first will become thick and viscid, but by continuing the application of heat, it will again assume a per- fectly liquid form. CASTING IN GLUE. 83 TO CAST IN GLUE. If a medal is so much sunk and engraved that you cannot get a plaster cast off, a mould may be obtained by pouring glue upon it. In this manner a bunch of grapes can be taken in the natural state, and by cutting the glue down the centre, the grapes can be extracted, and the mould used to produce a representation of the original in plaster. Isinglass may be similarly used, but it is first mixed with flake-white, in the state of powder. When the plaster is hard, place the whole in boiling water, when the glue will melt away, leaving a perfect cast of plaster grapes. TO MAKE A FINE GLUE, WHEREWITH YOU MAY CAST CURIOUS MEDALS. Steep isinglass in brandy, and when it is dis- solved boil it together with water, and pour it over any medal, and when dry it will appear perfect. It 84 CASTING IN BREAD PASTE. must be of a tolerably thick consistence, much like common glue. TO CAST IN BREAD PASTE. Take the inside of fresh bread, and work it up well with vermillion — the longer the better, until it becomes viscid and tough. It is then to be worked well into the mould. After having obtained the mould, it must be fastened down upon a piece of wood, by wetting it so as to prevent it from warp- ing as it dries. After it has been thoroughly dried you may oil it, and then obtain as many casts as you please from it, in plaster, wax, or sulphur. By means of bread-paste a traveller may always take a model of any small object of interest he meets with on his journey; and thus a proper knowledge of its mode of use becomes invaluable. Scrolls, ruins of tombs and temples, &c, have often thus been copied and brought home at a trifling cost. CASTING IN ISINGLASS AND RICE GLUE. 85 TO CAST FIGURES IN IMITATION OF IVORY. Make isinglass and strong brandy into a paste with powder of egg-shells, well ground. You may make it whatever colour you please, but cast warm water into your mould, which should be previously well oiled over. Leave the figure in the mould to dry; and on taking it out it will be found to bear a strong resemblance to ivory. RICE GLUE STATUARY. Mix rice flour intimately with cold water, and gently simmer it over the fire, when it readily forms a delicate and durable cement, not only answering the purpose of common paste, but admirably adapted to join together paper, card, &c. When made of the consistence of plastic clay, models, busts, basso- relievos, &c, may be formed ; and the articles when dry are very like white marble, and will take a high polish, being very durable. In this manner the 8 86 COMPOSITION FOR ORNAMENTS. Chinese and Japanese make many of their domestic idols. Any colouring matter may be used at plea- sure. A COMPOSITION FOR ORNAMENTS. Take pounded chalk, what quantity you please, acid thereto as much thin glue as will make it into paste, which mix well together. Then put it into moulds, being a little oiled, and press it well in ; after which take it out, and it will grow as hard as stone. You must make no more of it than you want for present use ; if left it grows hard, and cannot be used again, ON ALLOYS AND AMALGAMS. 87 ALLOYS, AMALGAMS, ETC. The formation of alloys appears to depend upon the chemical affinity of the metals for each other, and in some instances it seems to he wanting, for no combination occurs. Thus, according to Gellert, bismuth and zinc do not combine. The change of properties which metals undergo by combining, furnishes strong evidence of its aris- ing from chemical affinity and action. Thus, with respect to colour, copper, a reddish-coloured metal, by union with zinc, which is a white one, gives the well known "yellow alloy brass." The fusing point of a mixed metal, is never the mean of the temperature at which its constituents melt, and it is generally lower than that of the most fusible metal of the alloy. Alloy is a word used to designate either a natural or artificial compound of two or more metals ; ex- cept when mercury is one of them ; the mixture is then termed an amalgam,. The natural alloys are far less important sub- stances than those which are artificially procured. Thus arsenic occurs combined with the following 88 NATIVE ALLOYS, ETC. metals, namely, antimony, bismuth, cobalt, iron, nickel, and silver. There is also found a native alloy of antimony and nickel, and of antimony, cobalt, and nickel ; others might be mentioned ; but there is no instance of a native alloy, strictly speaking, being applied to any useful purpose. Whereas, the artificial alloys, as has been fully shown, are of the highest import- ance, both for the uses of common life, and for manu- facturing purposes. By uniting different metals, compounds are formed, which possess a combination of qualities not occurring in any one metal. Platina is always used in a pure state, and cop- per, iron, lead, and zinc, are also very commonly so used. But gold, silver, tin, antimony, and bismuth, are, as we have shown, generally alloyed ; the first three on account of their softness, and the two latter because they are extremely brittle. Gold and silver are hardened by alloying with copper; copper is hardened by zinc, tin, &c, &c. All alloys formed of brittle metals are brittle ; those made of ductile metals are in some cases duc- tile and in others brittle. When the proportions are nearly equal, there are as many alloys which are brittle as ductile — but when any of the metals is in excess they are most commonly ductile. In DENSITY OF METALS. 89 combining ductile and brittle metals, the compounds are brittle if the brittle metal exceed, or nearly equal the proportion of the ductile one ; but when the ductile metal greatly exceeds the brittle one, the alloys are usually ductile. The density of alloys sometimes exceeds, and in other cases is less than that which would result from calculation. The following alloys afford examples of " increased and diminished density:" — Increased Density. Gold and Zinc. Gold and Tin. Gold and Bismuth. Gold and Antimony. Gold and Cobalt. Silver and Tin. Silver and Bismuth. Silver and Antimony. Silver and Zinc. Silver and Lead. Copper and Zinc. Copper and Tin. Copper and Palladium. 8* Diminished Density. Gold and Silver. Gold and Iron. Gold and Lead. Gold and Copper. Gold and Iridium. Gold and Nickel. Silver and Copper. Iron and Bismuth. Iron and Antimony. Iron and Lead. Tin and Lead. Tin and Palladium. Tin and Antimony. 90 BRONZE, BELL, AND SPECULUM METALS. Increased Density. Diminished Density. Copper and Bismuth. Nickel and Arsenic. Copper and Antimony. Zinc and Antimony. Lead and Bismuth. Lead and Antimony. Platina and Molybdenum. Palladium and Bismuth. Not only are the properties of metals altered by combination, but different proportions of the same metals produce very different alloys. Thus, by combining 90 parts of cOpper with 10 parts of tin, an alloy is obtained of greater density than the mean of the metals ; and it is also harder and more fusible than the copper; it is slightly malleable when slowly cooled ; but, on the contrary, when heated to red- ness and plunged into cold water, it is very malle- able. This compound is known by the name of bronze. Again, as has been previously laid down, if 80 parts of copper be combined with 20 parts of tin, the compound is the extremely sonorous one, called bell metal. An alloy consisting of two-thirds copper, and one-third tin, is susceptible of a very fine polish, and is used as speculum metal. COMBINATION AND CHEMICAL ACTION. 91 It is curious to observe in these alloys, that in bronze, the density and hardness of the denser and harder metal are increased, by combining with a lighter and softer one ; while, as might be expected, the fusibility of the more refractory metal is in- creased by uniting with a more fusible metal. In bell metal, the copper becomes more sonorous by combination with a metal which is less so. These changes are clear indications of chemical action. It has been already observed that the natural alloys, considered as such, are not important bodies. The only one, if indeed that may be reckoned so, is the alloy of iron and nickel, constituting meteoric iron, and of which the knives of the Esquimaux appear to be made. The artificial metallic alloys are of the highest degree of utility. Thus, gold is too soft a metal to be used either for the purposes of coin or ornament ; it is therefore alloyed with copper. Silver, though harder than gold, would also wear too quickly unless mixed with copper ; and copper is improved both in hardness and colour by combination with zinc and tin, forming brass and bronze. 92 TABLE OF YELLOW BRASS. YELLOW BRASS. The following table exhibits the composition of several varieties of this species of brass. No. 1 is a cast brass, of uncertain origin. No. 2 is the brass of Jemappes. No. 3 is the sheet-brass of Stolberg, near Aix-la-Chapelle. No. 4 and 5, the brass for gilding, according to De Arcet. No. 6, the sheet- brass of Romilly. No. 7, English brass- wire. No. 8, Augsburg brass-wire. No. 9, the brass-wire of Neustadt, Eberswald, in the neighbourhood of Berlin. Metal. No.l. No. 2. No. 3. No. 4. No.5. No. 6. No. 7. No. 8. No. 9. Copper . Zinc. . . Lead . . Tin . . . 01.6 35.3 2.9 0.2 6-1.6 33.7 1.4 0.2 64.8 32.8 2.0 0.4 63.70 35.55 0.25 0.50 64.45 3244 2.86 0.25 70.1 29.9 7 Application of the Table. The Chinese Packfong, similar to our German silver, accord ing to Dr. Fyfe's analysis, page 108, is said to consist of— 40.4 parts of Copper equivalent to Zinc Nickel Iron 6 oz. 4 — 5 — 7 drams, full. 1 — full. 1 — nearly. 7 — nearly. 100.0 Parts. 16oz.O Avd. STATUE COMPOSITION. 107 KELLER S STATUE COMPOSITION. The brothers Keller, who were very celebrated statue founders, used an alloy, 10,000 parts of which contained 9140 parts of copper, 714 parts tin, 118 parts zinc, and 28 parts lead. This is the composi- tion of the statue of Louis XIV., which was cast at a single jet, by Balthazar Keller, in 1669. It is twenty-one feet high, and weighs 53,263 French pounds. These statues are usually miscalled bronze. The best brass consists of four parts of copper to one part of zinc. Bronze was well known to the Romans under the name of " orichalcum" who took advantage of its resemblance to gold, in robbing the temples and other public places of that precious metal. Thus Julius Caesar robbed the Capitol of 3000 pounds weight of gold ; and Vitellius despoiled the temples of their gifts and ornaments, and replaced them with this inferior metal. 106 PACKFONG AND COPPER. THE CHINESE PACKFONG,* According to Dr. Fyfe's analysis, is said to con- sist of 40.4 parts of copper 25.4 31.6 2.6 " a 100.0 parts. zinc nickel iron equiva- lent to f 6 oz. 7 dr. full. 4 oz. 1 dr. full. 5 oz. 1 dr. nearly. 7 dr. nearly. 16 oz. dr. COPPER. Copper, when mixed with as much zinc as possi- ble, that is 89 pounds copper to 100 pounds zinc, becomes white. The best " Goslar zinc" is from the Hartz, Germany. * Similar to our German silver. COMPOSITIONS. 109 SILVER STEEL. 1 part silver, 500 parts steel, according to Fara- day and Stodan. This alloy would be superior to the best steel. Steel also combines "with other metals, such as nickel, platinum, manganese, &c. COPPER AND ANTIMONY. 75 parts copper, and 25 parts antimony. This alloy is brittle, lamellated, of a violet colour, sus- ceptible of a fine polish, and is more fusible than copper. ANTIMONY AND TIN, COPPER AND BISMUTH. 100 parts of tin, 8 parts of antimony, 4 parts of copper, and 1 part of bismuth, constitute the com- pound commonly called pewter. 10 ] 10 COMPOSITIONS. BISMUTH AND LEAD. 1 part of bismuth, and 1 part of lead, a very te- nacious alloy, melting at 165° Centigrade, equiva- lent to 370° Fahrenheit. 2 parts of lead to 1 part of bismuth, gives an alloy which dilates powerfully at the time of cooling. (This property makes it extremely suitable to all castings in which the greatest sharpness and finish are desirable. — H. Meigs.) FULL MEASURE OF CAPACITY OF TIN AND LEAD. 82 parts tin, and 18 parts lead. BRILLIANTS OF FAHLUN, Thus called, are made from 29 parts of tin, and 19 parts of lead. A very fusible and brilliant alloy. COMPOSITIONS OF METALS. Ill QUEEN S METAL, Imitating silver, has great metallic lustre : 9 parts tin, 1 part lead, 1 part antimony, and 1 part bismuth. TIN AND ZINC. 1 part tin, and 1 part zinc, is almost as tenacious as brass, and melts at 460° to 500° Centigrade, 900° Fahrenheit. TIN AND IRON. These two metals may be alloyed in all propor- tions. 35 parts of tin to 65 parts of iron, form an alloy of a clear crystalline gray, and so brittle that it may be reduced to an impalpable powder. ]12 SILVERING COPPER— MOSAIC GOLD. TO SILVER COPPER. Precipitate silver from its nitric solution by the immersion of polished plates of copper. Take of this silver 20 grains, supertartrate of potass, 2 drachms, common salt, 2 drachms, and of alum, half a drachm. Mix the whole well together. Then take the article to be silvered, clean it well, and rub some of the mixture, previously a little moistened, upon its surface. The silver surface may be polished with a piece of soft leather. The dial-plates of clocks, scales of barometers, &c, are plated thus. MOSAIC GOLD (or molu), May be thus made : take copper and zinc, equal parts ; mix them together at the lowest possible temperature at which copper will fuse, and stir until a perfect mixture of the metals is effected. Then add gradually small portions of zinc at a time, until the alloy acquires a proper colour, which is BRONZING BRASS. 113 perfectly white while in the melted state. It should then at once be cast into figured moulds. This alloy should contain from 52 to 55 per cent, of zinc. TO BRONZE BRASS, ETC. To 6 pounds of muriatic acid, add 2 pounds of oxide of iron, and 1 pound of yellow arsenic. Mix all well together, and let it stand for two days, fre- quently shaking it in the mean time, when it is fit for use. Whatever may be the article which requires bronzing, let it be perfectly cleaned, and free from grease ; immerse it in the above solution, and let it stand for three hours, or rather till it will turn en- tirely black. Then wash the spirits off, and dry it in sawdust, which has been found the best. After the article is perfectly dry, apply to it some wet black, the same as used for stones, and then polish it with some dry black-lead and a brush, and it is ready for lacquering. 10* 114 LACQUERS. LACQUERS. Lacquers are used upon polished metals and wood, to impart the appearance of gold. As they are want- ed of different depths and shades of colours, it is best to keep a concentrated solution of each colouring ingredient ready, so that it may at any time be added to produce any desired tint. 1. Deep G old-coloured Lacquer. — Seed lac, three ounces ; turmeric, one ounce ; dragon's blood, a quarter of an ounce; alcohol, one pint. Digest for a week, frequently shaking. Decant and filter. 2. Gold-coloured Lacquer. — Ground turmeric, one pound; gamboge, an ounce and a half; gum- sandarach, three pounds and a half ; shell lac, three- quarters of a pound (all in powder) ; rectified spirits of wine, two gallons. Dissolve, strain, and add one pint of turpentine varnish. 3. Bed-coloured Lacquer. — Spanish anatto, three pounds ; dragon's blood, one pound ; gum-sandarach, three pounds and a quarter; rectified spirits, two LACQUERS. 115 gallons; turpentine varnish, one quart. Dissolve and mix as the last. 4. Pale Brass-coloured Lacquer. — Gamboge, cut small, one ounce ; cape aloes, ditto, three ounces ; pale shell lac, one pound ; rectified spirits, two gal- lons. Dissolve and mix as No. 2. 5. Seed lac, dragon's blood, anatto, and gamboge, of each a quarter of a pound ; saffron, one ounce ; rectified spirits of wine, ten pints. Dissolve and mix as No. 2. The following receipts make most excellent lac- quers. 1. Gold Lacquer. — Put into a clean four-gallon tin 1 pound of ground turmeric, 1-J ounces of powdered gamboge, 8J ounces of powdered gum-san- darach, f of a pound of shell lac, and 2 gallons of spirits of wine. After being agitated, dissolved, and strained, add one pint of turpentine varnish, well mixed. 2. Bed Lacquer. — 2 gallons of spirits of wine, 1 pound of dragon's blood, 3 pounds of Spanish 116 ' LACQUERS. anatto, 3J pounds of gum-sandarach, 2 pints of tur- pentine. Made as No. 1 lacquer. 3. Pale Brass Lacquer. — 2 gallons of spirits of wine, 3 ounces of cape aloes cut small, 1 pound of fine pale shell lac, 1 ounce of gamboge cut small, no turpentine varnish. Made exactly as before. But observe, that those who make lacquers, fre- quently want some paler, and some darker, and sometimes inclining more to the particular tint of certain of the component ingredients. Therefore, if a four-ounce phial of a strong solution of each ingredient be prepared, a lacquer of any tint can be procured at any time. 4. Pale Tin Lacquer. — Strongest alcohol, 4 ounces ; powdered turmeric, 2 drachms ; hay saf- fron, 1 scruple ; dragon's blood in powder, 2 scru- ples ; red saunders, J scruple. Infuse this mixture in the cold for 48 hours, pour off the clear, and strain the rest ; then add powdered shell lac, J ounce ; sandarach, 1 drachm ; mastic, 1 drachm ; Canada balsam, 1 drachm. Dissolve this in the cold by frequent agitation, laying the bottle on its side, to present a greater surface to the alcohol. When dissolved, add 40 drops of spirits of tur- pentine. LACQUER AND BRONZE LIQUID. 117 5. Another Deep Gold Lacquer. — Strongest alco- hol, 4 ounces ; Spanish anatto, 8 grains ; powdered turmeric, 2 drachms ; red saunders, 12 grains. In- fuse and add shell lac, &c, as to the pale tin lac- quer ; and when dissolved add 30 drops of spirits of turpentine. N. B. Lacquer should always stand till it is quite fine, before it is used. GREEN BRONZE LIQUID. Take one quart of strong vinegar, half an ounce of mineral green, half an ounce of raw umber, half an ounce of sal-ammoniac, half an ounce of gum arabic, two ounces of French berries, half an ounce of copperas, and about three ounces of green oats, if these can be procured, although, if they cannot, the preparation will succeed perfectly well without them. Dissolve the whole in a strong earthen ves- sel, adding the berries and the oats, over a gentle fire ; bring the compound to boil, then allow it to cool, and run it through a flannel bag, when the bronze will be ready for use. 118 SILVERING IVORY AND ZINCING. TO SILVER IVORY. Immerse a slip of ivory in a weak solution of nitrate of silver, and let it remain until the solution has imparted to it a deep yellow colour. Then take it out, and immerse it in a tumbler of clear water, and expose it in the water to the rays of the sun. After it has been exposed thus for about three hours, the ivory acquires a black colour, which on being burnished soon becomes a brilliant silver one. ZINCING. Copper and brass vessels may be covered with a firmly adherent layer of pure zinc, by boiling them in contact with a solution of chloride of zinc, pure zinc turnings being at the same time present in con- siderable excess. The same object may be attained by means of zinc, and a solution of sal-ammoniac, or caustic potassa. * TABLES. 119 TABLE I. — METAL PLATES. This table shows the weight of a square foot of different metal plates, of thicknesses of one six- teenth of an inch ' to one inch, advancing by a sixteenth : — Six- Wrought Cast Cast Cast Cast Cast Cast Cast teenths. Iron. Iron. Copper. Brass. Lead. Ziuc. Tin. lbs. Silver. lbs. lbs. lbs. lbs. lbs. lbs. lbs. 1 2.5 2.3 2.9 2.7 3.7 2.3 2.4 3.4 2 5.1 4.7 5.7 5.5 7.4 4.7 4.7 6.8 3 7.6 7.0 8.6 8.2 11.1 7.0 7.1 10.2 4 10.1 9.4 11.4 11.0 14.8 9.4 9.5 13.6 5 12.7 11.7 14.3 13.7 18.5 11.7 11.9 17.0 6 15.2 14.0 17.2 16.4 22.2 14.0 14.2 20.5 7 17.9 16.4 20.0 19.2 25.9 16.4 16.6 23.9 8 20.3 18.8 22.9 21.9 29.5 18.7 19.0 27.3 9 22.8 21.1 25.7 24.6 33.2 21.1 21.4 30.7 10 25.4 23.5 28.6 27.4 36.9 23.4 23.7 34.1 11 27.9 25.8 31.4 30.1 40.6 25.7 26.1 37.5 12 30.4 28.1 34.3 32.9 44.3 28.1 28.5 40.9 13 32.9 30.5 37.2 35.6 48.0 30.4 30.9 44.3 14 35.5 32.9 40.0 38.3 51.7 32.8 33.2 47.7 15 38.0 35.2 42.9 41.2 55.4 35.1 35.6 51.1 1G 40. G 37.6 45.8 43.9 59.1 37.5 38.0 54.6 TABLE II. — CAST METAL BALLS. Diam. — Ins. Iron. — lbs. Copper. — lbs. Brass. — lbs. Lead. — lbs. 1 2 3 1.1 1 6 1.3 3 1.3 3 14 1.7 3 3.7 4.5 4.3 5.8 4 8.7 10.7 10.2 13.8 5 17.0 20.8 19.9 26.9 6 29.5 35.9 34.3 46.4 7 46.8 57.1 54.5 73.7 8 69.8 85.2 81.4 110.1 9 99.4 121.3 115.9 156.7 10 13G.4 166.4 159.0 215.0 120 TABLES. TABLE III. — CAST IRON PIPES. This table shows the weight of cast iron pipes 1 foot long, of bores from 1 inch to 12 inches diam- eter, advancing by J of an inch ; and of thicknesses from J inch to 1 J inch, advancing by J of an inch. Bore. K % M % % % 1 iy 8 W± In. M.s. lbs. lbs. lbs. lbs. lbs. lbs. lbs. lis. 1 ;;.l 5.1 7.4 10.0 L2.9 16.1 19.6 23.5 27.6 m 3.7 6.0 8.6 11.5 14.7 18.3 22.1 26.2 30.7 VA 4.3 6.9 9.8 13.0 16.6 20.4 24.5 29.0 33.7 m 4.9 7.8 11.1 14.6 18.4 22.6 27.0 31.8 36.8 2 5.5 8.8 12.3 16.1 20.3 24.7 29.5 34.5 39.9 2^ 6.1 9.7 13.5 17.6 22.1 26.8 31.9 37.3 43.0 V/l 6.7 10.6 14.7 19.2 23.9 2S.9 34.4 40.0 46.0 2^4 7.4 11.5 16.0 20.7 25.7 31.1 36.8 42.8 49.1 3 8.0 12.4 17.2 22.2 27.6 33.3 39.3 45.6 52.2 &A 8.6 13.3 18.4 23.8 29.5 35.4 41.7 48.3 55.2 2>y 2 9.2 14.2 19.6 25.3 31.3 37.6 44.2 51.1 58.3 m 9.8 15.2 20.9 26.9 33.1 39.7 46.6 53.8 61.4 4 10.4 16.1 22.1 28.4 35.0 41.9 49.1 56.6 64.4 i\i 11.1 17.1 2.3!4 30.0 36.9 44.1 51.6 59.4 67.6 4M 11.7 18.0 24.5 31.4 38.7 46.2 54.0 62.1 70.6 m 12.3 18.9 25.8 33.0 40.5 48.3 56.5 64.9 73.6 5 12.9 19.8 27.0 34.5 42.3 50.5 58.9 67.6 76.7 5M 13.5 20.7 28.2 36.1 44.2 52.6 61.4 70.4 79.8 hYo 14.1 21.6 29.5 37.6 46.0 54.8 63.8 73.2 82.8 5M 14.7 22.6 30.7 39.1 47.9 56.9 66.3 76.0 85.9 6 15.3 23.5 31.9 40.7 49.7 59.1 68.7 78.7 88.8 6 K l<;.o 24.4 33.1 42.2 51.5 61.2 71.2 81.2 92.0 G% 16.6 25.3 34.4 43.7 53.4 63.4 73.4 84.2 95.1 m 17.2 26.2 35.6 45.3 55.2 65.3 76.1 87.0 98.2 7 17.8 27.2 36.8 46.8 56.8 67.7 78.5 89.7 101.2 7^ 18.4 28.1 38.1 48.1 58.9 69.8 81.0 92.5 104.3 iy 19.0 29.0 39.1 49.9 G0.7 72.0 83.5 95.3 107.4 ?% 19.6 29.7 40.5 51.4 62.6 74.1 85.9 98.0 110.5 8 20.0 30.8 41.7 52.9 64.4 76.2 88.4 100.8 113.5 8^ 20.9 31.7 43.0 54.5 66.3 78.4 90.8 103.5 116.6 sS 21.7 32.9 44.4 56.2 68.3 80.8 93.5 100.5 119.9 8% 22.1 33.6 45.4 57.5 70.0 82.7 95.7 109.1 122.7 9 22.7 34.5 46.6 59.1 71.8 84.8 98.2 111.8 125.8 9K 23.3 35.4 47.9 60.6 73.6 87.0 100.6 114.6 128.9 9>3 23.9 36.4 49.1 62.1 75.5 89.1 103.1 117.4 131.9 9?4 24.6 37.3 50.3 63.7 77.3 91.3 105.5 120.1 135.0 10 25.2 38.2 51.5 65.2 79.2 93.4 108.0 122.8 138.1 1014 25.8 39.1 52.8 66.7 81.0 95.6 110.4 125.6 141.1 10H 26.4 40.0 54.0 68.3 82.8 97.7 112.9 128.4 144.2 io?| 27.0 41.0 55.2 69.8 84.7 99.9 115.4 131.2 147.3 11 27.6 41.9 56.5 71.3 86.5 102.0 117.8 133.9 150.3 ! 1 1 ■ 28.2 42.S 57.7 72.9 88.4 104.2 120.3 136.7 153.4 11)1 28.8 43.7 58.9 74.4 90.2 106.3 122.7 139.4 156.4 u$| 29.5 44.6 60.1 75.9 92.0 108.5 125.2 142.2 159.5 162.6 12 30.1 45.6 61.4 77.5 93.6 110.6 127.6 145.0 TABLES. 121 TABLE IV. — CAST METAL CYLINDERS.* Diam. — Ins. Iron. — lbs. Copper. — lbs. Brass. — lbs. 1 Lead. — lbs. 1 2.5 3.0 2.9 3.9 2 9.8 12.0 11.4 15.5 3 22.1 27.0 25.8 34.8 4 39.3 47.9 45.8 61.9 5 61.4 74.9 71.6 96.7 6 88.4 107.8 103.0 139.3 7 120.3 146.8 140.2 189.6 8 157.1 191.7 183.2 247.7 9 198.8 242.7 231.8 313.4 10 245.4 299.5 286.2 387.0 TABLE V. — SPECIFIC GRAVITY AND WEIGHT OF MATERIALS. METALS. Specific Wt. of l "Wt. of 1 Gravity. cubic foot. cubio inch. oz. lbs. oz. Antimony, cast .... 6702 418.9 3.878 Arsenic . 5763 360.2 3.335 Bismuth, cast 9822 613.9 5.684 Brass, cast 8396 524.8 4.859 Brass, wire . 8544 534.0 4.944 Bronze . 8222 513.4 4.753 Cobalt, cast 7811 488.2 4.520 Copper, cast 8788 549.3 5.086 Copper, sheet 8915 557.2 5.159 Copper, wire 8S78 554.9 5.136 Gold, pure . 19258 1203.6 11.161 Gold, hammered 19362 1210.1 11.205 Gold, standard 17647 1102.9 10.230 Gun metal 8784 549.0 5.083 Iron, bars wrought 7786 486.6 4.506 Iron, cast 7207 450.4 4.171 Lead, cast . 11352 709.5 6.569 Mercury, solid . 15632 977.0 9.046 Mercury, fluid 13568 848.0 7.852 Nickel, cast 7807 487.9 4.518 Platinum, pure 19500 1218.8 11.285 Platinum, hammered 20336 1271.0 11.767 Silver, pure 10474 654.6 6.061 Silver, hammered 10511 656.9 6.083 Silver, standard . 10534 65S.4 6.096 Steel, tempered 7818 488.6 4.524 Steel, soft . 7833 489.6 4.533 Tin, cast 7291 455.7 4.244 Type metal . 10450 653.1 6.047 Zinc, cast 7190 449.4 4.161 11 * The cylinders are solid, each one foot in length. 122 SPECIFIC COHESION OF METALS. TABLE VI. — SPECIFIC COHESION AND STRENGTH OF METALS. In the following table of specific cohesion, the co- hesion of plate glass is assumed as unity. If any of the numbers in this table be multiplied by 9240, the product will express the force in pounds, which would tear asunder a bar of the corresponding ma- terial, of one inch square of transverse section. Thus, the specific cohesion of steel, razor temper, is 15.927 ; whence the extreme cohesion of a bar one inch square is 15.92T X 9240 = 147,165.48 pounds. Specific cohesion. Antimony, cast 0.113 Bismuth, cast . 0.345 to 0.319 Copper, wire 6.606 " cast, Barbary . 2.396 " " Japan 2.152 Gold, wire 3.279 cast • • < 2.171 Iron, wire 12.004 to 9.108 " bar . 8.964 to 5.839 " " best quality 7.006 " " German, B R . 9.880 to 6.514 SPECIFIC COHESION OF METALS. 123 Iron, bar, Swedish, L " " Liege " " German, L " " Spanish . " " Oosement " " fine grained " " medium fineness " " coarse grained " cast, French . " " German < " English Lead, milled . " wire " cast, English Platinum, wire Silver, wire . cast • • Steel, razor temper " soft . Tin, wire " cast, English block " " Banca . " " Malacca . Zinc, wire " patent sheet . " cast, Goslar . Specific cohesion. 9.445 to 7.296 8.794 to 6.621 9.119 to 7.382 8.685 8.142 to 7.296 5.306 3.618 2.172 7.470 to 4.000 7.250 5.520 to 4.334 0.354 0.334 to 0.270 0.094 5.995 to 5.625 4.090 4.342 . 15.927 . 12.739 0.757 0.706 to 0.565 0.391 0.342 2.394 1.762 0.312 to 0.286 124 DIRECT COHESION OF METALS. TABLE VII. — DIRECT COHESION OF METALS. The numbers in this table of experiments express the direct cohesion of bars one inch square in tons, of 2240 pounds. Tons. lbs. Iron bar, cast horizontally 8 32 " " vertically 8 69 Cast steel, previously tilted . 59 93 Blistered steel, reduced by hammer 59 43 Shear " " " 56 97 Swedish iron " " 32 15 English " " " 24 93 Hard gun metal .... 16 23 Wrought copper, reduced by hammer 15 8 Cast " " " 8 51 Fine yellow brass .... 8 01 Cast tin .... 2 11 Cast lead ..... 81 Wrought iron, mean of 26 experiments, Brunei 31 20 " " 9 Brown 29 25 " " 8 Telford 25 00 Iron cable, " 13 Brown 21 25 RESISTANCE OF METALS. 125 TABLE VIII. — RESISTANCE OF METALS TO PRESSURE. In this table of experiments the number of pounds are the weights required to crush cubes of one-quar- r inch in the edge. lbs. Iron, cast vertically 11136 " " horizontally . 10114 Copper, cast 7318 " wrought . 6440 Brass .... 10304 Tin, cast . 966 Lead, cast 483 TABLE IX. — RESISTANCE OF METALS TO TORSION. This table of experiments by Brandreth, exhibits only the relative resistance to torsion, that of lead being assumed as unity. 11* 126 5 1 SOLDERS. lbs. Cast steel 19.56 Shear steel . 17.06 Blister steel . 16.69 English iron . 10.13 Swedish iron 9.50 Hard gun metal 5.00 Fine yellow brass 4.69 Copper . 4.31 Tin 1.44 Lead 1.00 GOLD AND SILVER SOLDERS. Hard Solder for Gold is prepared from gold and silver, or from gold and copper, or from gold, silver, and copper. Gold Solder. — 66.6 parts of gold, 16.7 parts of silver, and 16.7 parts of copper. Hard Solder for Silver. — Equal parts of silver and brass ; but made easier of fusion by the admix- ture of one-sixteenth of zinc. ON SOLDERS AND SOLDERING. 127 Another Silver Solder. — 19 parts fine silver, 1 part copper, 10 parts brass. Another Silver Solder. — 66.6 parts silver, 30.4 parts copper, 3.4 parts brass. BRASS SOLDER. Brass mixed with a sixth, an eighth, or even one- half of zinc. Another Brass Solder. — 12 pounds copper, and 11 pounds of zinc. METHOD OE SOLDERING GOLD AND SILVER. After the solder is cast into an ingot, it would be more ready for use if you were to draw it into small wire, or flat it between two rollers. After that cut it into little bits, then join your work together with fine soft iron wire, and with a camel's- hair pencil dipped in borax, finely powdered and 128 TO CLEANSE AFTER SOLDERING. well moistened with water, touch the joint intended to be soldered, placing a little solder on the joint. Apply it on a large piece of charcoal, and with a blow-pipe and lamp blow upon it through the flame until it melts the solder, and it is done. TO CLEANSE SILVER AFTER IT IS SOLDERED. Make it just red hot, and let it cool ; then boil it in alum water, in an earthen vessel, and it will be as clean as when new. TO CLEANSE GOLD AFTER IT IS SOLDERED. Put it through the same process as silver, but, instead of alum-water, boil it in wine and sal-ammo- niac. SILVER-SOLDER FOR JEWELLERS. 19 dwts. of fine silver, 1 dwt. of copper, and 10 dwts. of brass. ALLOYS AND SOLDER. 129 TRINKET COMPOSITION. 75 parts gold, 25 parts copper, and a little silver. SILVER-PLATE AND MEDAL ALLOY. 95 parts silver, and 5 parts of copper. GOLD COIN OF AMERICA ALLOY. 90 parts gold, 2.5 silver, and 7.5 copper. SOLDER FOR IRON. Nothing here is necessary but good tough brass, with borax, applied, mixed with water to the con- sistence of cream. 130 SOLDERING AND BURNING METALS. SOLDERING AND BURNING METALS. Besides the more common processes of soldering, properly so called, the process of burning together must frequently be employed, as in making small additions to old castings, and repairing small defects in new ones. In operations of this kind, very high degrees of heat are often required. This caused the introduc- tion of the blow-pipe into the workshop. Perhaps the most powerful and convenient form of this in- strument is that invented in France, by Count de Richemont, and patented in England by Mr. Del- bruch. A figured description of the same, with its use explained, we now present to our readers. SOLDERING AND BURNING METALS. 131 The elastic tube h supplies hydrogen from the generator, and the pipe a supplies atmospheric air from a small pair of double bellows 5, worked by the foot of the operator, and compressed by a constant weight iv ; the two pipes meet at the arch, and pro- ceed through the third pipe e to the small jet/, from whence proceeds the flame. All the connexions are by elastic tubes, which allow perfect freedom of motion, so that the portable blow-pipe is carried to the work. In soldering by the autogenous process, the works are first prepared and scraped clean as usual ; the hydrogen is ignited, and the size of the flame is pro- portioned by the stop-cock li; the air is then ad- mitted through a, until the flame assumes a fine pointed character, with which the work is united. The gas generator bears some resemblance to Pepys' gasometer. . When it is first charged, the stopper 1 is unscrewed, and the lower chamber is nearly filled with curly shreds of sheet zinc, and the stopper is replaced. The cover is now removed, and a plug with a long wire is inserted from the top into the hole near 3 ; the upper chamber is next filled with dilute sulphuric acid (1 acid and 6 water), until it is just seen through the central hole to rise above the plate immediately beneath it. This mea- 132 AERO-HYDROGEN BLOWPIPE. sures the quantity of liquid required to charge the vessel without the risk of overflow. The plug is now withdrawn from 3, and the cocks 4, and h, being opened, the air escapes from the lower vessel by the pressure of the column of water which enters beneath the perforated bottom 5, upon which the zinc rests. The cocks 4 and li are now closed, and by the decomposition of the water hydrogen is gene- rated, which occupies the upper part of the lower chamber, and drives the dilute acid upwards, through the aperture 3, so as to place matters in the posi- tion of the engraving, which represents the gene- rator about two-thirds filled with gas. The gas issues through the pipe h when both cocks are opened, but it has to proceed through a safety-box, 6, in which the syphon-tube clips two or three inches into a little plain water, introduced at the lateral aperture 7 : by this precaution the con- tents of the gasometer cannot be ignited, as should the flame return through the pipe 7i, it would be in- tercepted by the water in the safety-box. After three or four days' constant work, the liquid be- comes converted into the sulphate of zinc, and is withdrawn through the plug 8 ; the vessel is then refilled with fresh dilute acid, as already explained, but the zinc lasts a considerable time. AERO-HYDROGEN BLOWPIPE. 133 The generators are made of lead, or, where porta- bility and lightness are required, of copper washed with lead, and all the exposed parts of the brass work are washed and united with lead to defend them from the acid. Occasionally the air is likewise supplied by aerometers, or vessels somewhat resem- bling the gas generator, but which are only filled with common air, and therefore do not require the zinc or acid. The difference between the aero-hydrogen blow- pipe described above, and the oxy-hydrogen blow- pipe of Dr. Hare, is this : — in the latter the pure gases (oxygen and hydrogen) are mixed in the exact proportions of two volumes of hydrogen to one of oxygen — which quantities, when combined, con- stitute water, and during combination evolve the greatest amount of heat. The aero-hydrogen blow- pipe is supplied with common air and pure hydro- gen. 12 134 SOFT SOLDERS. SOFT SOLDERS. Tin and lead in equal parts. Easier of fusion still is tin, lead, and bismuth, in equal parts ; or one or two bismuth, one lead, and one tin, easier still. For soft soldering brass, tin-foil makes a fine juncture, applied between the joints, care being taken to avoid too much heat. This is most excellent for fine brass work. The tin-foil must be moistened in a strong solution of sal-ammoniac. A SOLDER FOR LEAD. 2 parts lead and 1 part tin. Its goodness is tried by melting it and pouring the bigness of a dollar piece upon the table ; for if it be good there will arise little bright spots in it. Apply rosin when you use the solder. SOLDER, PEWTER, AND WHITE METAL. 135 PLUMBER S SOLDER. 1 part bismuth, 5 parts lead, and 3 parts tin. forms a compound of great importance in the arts. COMPOSITIONS OE PEWTER. 1. 100 parts tin, 17 parts of antimony ; the French add a little copper. 2. 12 pounds of tin, 1 pound of antimony, 4 ounces of copper. 3. 7 pounds of tin, 1 pound of lead, 6 ounces cop- per, 2 ounces zinc. Melt the copper first. WHITE METAL. 10 ounces lead, 6 ounces bismuth, and 4 drachms of antimony ; or, 2 pounds of antimony, 8 ounces of brass, and 10 ounces of tin. 136 COMPOSITIONS OF SOFT METAL. MOSAIC MIXTURE. Equal parts of tin, bismuth, and mercury, forms a metal used for various ornamental purposes. SILVERY-LOOKING METAL. A very fine silvery-looking metal is made from 100 parts tin, 8 parts antimony, 1 part bismuth, and 4 parts copper. METAL FOR FLUTE VALVE KEYS. 4 ounces of lead and 2 ounces of antimony. GERMAN TITANIUM. 2 drachms of copper, 1 ounce of antimony, and 12 ounces of tin. COMPOSITIONS OF SOFT METAL. 137 SPANISH TITANIUM. 8 ounces of scrap iron or steel, 1 pound of anti- mony, and 3 ounces of nitre. The iron or steel must be heated to whiteness, and the antimony and nitre added in small portions. Two ounces of this compound are sufficient to harden one pound of tin. BRITANNIA METAL. 4 ounces of plate brass, 4 ounces of tin ; when fused add 4 ounces of bismuth, and 4 ounces of an- timony. This composition is added at discretion to melted tin. COLUMBIA METAL. 4J pounds of tin, \ pound of bismuth, \ pound of antimony, and \ pound of lead ; or, 100 pounds of tin, 8 pounds of antimony, 1 pound of bismuth, and 12* 138 TYPE METALS. 4 pounds of copper. This alloy is used for making tea-pots, and other vessels which imitate silver. TYPE METAL. 10 pounds of lead, and 2 ounces of antimony. The antimony is added when the lead is in a state of fusion. The antimony gives hardness to the lead, and prevents its contraction when cooling. For Small Types. — 9 pounds of lead, 2 pounds of antimony, and 1 pound of bismuth. The anti- mony and bismuth are added when the lead is melted. This alloy expands in cooling ; the mould is there- fore entirely filled when the metal is cold, and no blemish is found in the letters. Stereotype plates are formed of this alloy. Some employ tin instead of bismuth. Type Metal of the French Letter Founders. — Four-fifths of lead, and one-fifth of regulus of anti- mony. The letter founders of Berlin use 11 pounds of GERMAN SILVER. 139 antimony, 25 pounds of lead, and 5 pounds of iron. Many add tin, copper, and brass ; while some make their types from 3 parts lead, to 1 of antimony. GERMAN SILVER. 1. 25 parts nickel, 20 parts zinc, and 60 parts copper. If for casting add 3 parts of lead. 2. 16 parts copper, 8 parts zinc, and 3J parts nickel. 3. 8 parts of copper, 3 J parts of zinc, and 2 parts of nickel. 4. 28 parts copper, 13 parts zinc, and 7J parts nickel. 5. Copper, 8 parts ; zinc, 3 J parts ; nickel 3 parts. This last is a very beautiful compound. It has the appearance of silver a little below standard. By some persons it is even preferred to the more ex- 110 SPECULUM METALS. pensive compound. Manufacturers are strongly re- commended not to use a metal inferior to this. SPECULUM METAL. 1. Copper, 64 parts ; grain tin, 29 parts. Melt the metals separately, under a little black flux. In- corporate thoroughly by stirring with a wooden spatula ; then run the metal in the mould, so that the face of the intended mirror may be downwards. 2. Copper, 32 parts ; tin, 14 parts ; arsenic, 2 parts. A very good metal. 3. Copper, 32 parts; tin, 13J parts; arsenic, 1J parts. 4. Copper, 32 parts; tin, 15 parts; arsenic, 2 parts. Better than 2 and 3. 5. Copper, 32 parts ; tin, 15 parts ; brass, 1 part ; silver, 1 part; arsenic, 1 part. A most excellent metal, and by far the whitest, hardest, and most re- flective metal I have ever yet met with. SPECULUM METALS. 141 6. Copper, 6 parts; tin, 2 parts; arsenic, 1 part. Sir Isaac Newton's mixture. It is a compact metal enough, but very yellow when polished. 7. Copper, 3 parts ; tin, 1J parts. Compact, and whiter than the last. 8. Brass, 6 parts ; tin, 1 part. Compact, but too yellow. 9. 2 parts of 7th composition, and 1 part of 8th. Compact, but much too yellow when polished. 7, 8, and 9, are experiments by Professor Molyneux, F. R. S. 10. Copper, 32 parts ; tin, 2 parts ; arsenic, 1 part. A pretty good metal, but polishes too yellow. Professor Mudge's composition. 142 REMARKS. REMARKS. In melting arsenic, nitre is a good flux for fixing it with other metals. In using iron filings in your compositions, use corrosive sublimate (viz. chloride of mercury) for fixing it. Powdered flint glass also makes a most excellent flux for copper, tin, and arsenic. No. 5. This metal, when broken, should appear of a bright, glassy, and quicksilver complexion. If it appears hard and of a dead white, more tin must be added. The copper will sometimes take sixteen ounces of tin, if it is very pure. If it appears bluish and rough, more copper or brass must be added. It is somewhat singular that arsenic, though par- ticularly recommended by Sir Isaac Newton, Dr. Olynthus Gregory, and others, for giving homo- geneity to metallic compositions, should be so hastily thrown aside by the founders. This imprudent dis- use of it, I can only attribute to the disagreeable fumes or vapours, which arise when it is introduced into the crucible, to the melted mixture, which may produce disagreeable effects upon the operators, if REMARKS. 143 proper care be not taken to prevent them from being received into the lungs. All the precaution necessary, is to bruise the arsenic coarsely, and in- troduce it into the crucible with a pair of tongs, having tied it up in a piece of paper, giving it then a stir with a wooden spatula made of birch, during which time retaining your breath — avoid it till you can see no more vapours arise from the crucible, when the metal will be ready to pour. The common black flux is made of two parts of tartar, and one of nitre. I have always found from adding a small quantity of arsenic, viz., from one-half ounce to one ounce to the pound of metal, that it would considerably im- prove even porous metal, and make it harder, like- wise, as well as whiter. In making speculums, the casting should be taken from the mould red-hot, and put into a quantity of hot ashes to anneal it, or else it will break in the sand. Let it remain in the ashes till the whole be- comes cold. Professor Nevil Masculyne, speaking of arsenic, says — I have been assured by two ingenious experi- mental philosophers that the fumes of arsenic, even when the garlic smell is very strong, are not in the least prejudicial to the lungs. 144 ' PLATINA. A careful study of the above remarks will be of inestimable advantage to the practical brass founder, saving him both loss of work, as well as loss of time. PLATINA. Mirrors for telescopes, &c, are made of pla- tina, of exquisite beauty. The Spaniards are in the habit of mixing it with iron, in order to form gun- barrels, which are said never to rust, and which are much stronger than iron barrels alone, as it gives to the iron a remarkable toughness. It forms a valu- able coating for copper and iron, and may hereafter become precious for the formation of coins and medals. Platina, in its malleable state, may be cut with a knife ; but with steel it forms an alloy not to be touched with a file. The nitro-muriatic acid is the proper solvent for platina. ARSENIC. 145 ON THE PROPERTIES OF ARSENIC. Arsenic is a brittle metal, and, in the recent frac- ture, of a lively bright colour, between tin-white and lead-graj ; but on exposure to the air it soon loses its metallic lustre, and turns prismatic, dull, and at last black. Its specific gravity is, according to Professor Mudge, between 8.310 and 5.763, ac- cording to its texture. Its hardness surpasses that of copper, but its ductility is so little, and it brittleness so great, that it is readily converted into a powder by the hammer. It is entirely volatilized when heated to 356° Fahr. It sublimes in close vessels, and then crystallizes in tetrahedra, or octahedra. When heated with the excess of air, it emits a strong smell of garlic, and burns, with a bluish white flame. It combines with sulphur by fusion. It unites to phosphorus, and combines with most of the metals. Besides giving a white colour to copper, it renders many of the ductile metals brittle. "When mixed with hyper-oxygenated muriate of potash, it deto- nates strongly by the stroke of a hammer. It is soluble in hydrogen gas by heat. It does not decom- 13 ' 146 EXPERIMENTS. pose water alone ; it decomposes sulphuric acid by heat. The nitric and nitrous acid oxidate it rapidly. The muriatic acid attacks it with heat. The oxy- genated muriatic acid (now termed chlorine), when in a gaseous state, inflames it instantly. It is nearly unalterable by the fluoric, boracic, phosphoric, and carbonic acids. It unites with alkaline sulphurets and hydro-sulphurets. It is a deadly poison. If you insert a little arsenic, reduced to fine powder, between two polished plates of copper, and bind closely together with iron wire, and heat them, the inner surfaces of the copper plates will be ren- dered white by the arsenic. Experiment No. 1. Experimental proofs of the properties of arsenic. Arsenic burns and is vola- tilized by heat. — Introduce into a crucible, made red-hot in a coal fire, a small quantity of arsenic, and it will begin to burn and become volatilized. If this crucible be covered with another, and the joinings luted with clay, the arsenic will be found in the upper one in brilliant crystals. Experiment No. 2. — The union of arsenic with copper may likewise be effected by fusing 1 part of arsenic with 4 of copper, in a common crucible. FONTAINEMOREAU'S ALLOYS. 147 The alloy produced is a white metal. It is neces- sary in this experiment to cover the substances in the crucible with common salt, to prevent the action of the air. FONTAINEMOREAU'S NEW" ALLOYS OF ZING, A SUB- STITUTE FOR BRONZE, COPPER, AND BRASS. An invention of a new alloy of zinc, with small proportions of other metals, found to possess very peculiar advantages, has lately been introduced into England, where it has been patented in the name of M. Fontainemoreau. It is likely to prove of great utility in the manufacture of machinery, and in castings relating to the fine arts. As a substi- tute for copper and bronze it already bids fair to be extensively adopted. The proportions of metals which have been found most advantageous in forming varieties of the alloy, after very numerous and extensive experiments, are as follows : — No. 1. Zinc, 90 parts; copper, 8 parts; cast iron, 1 part ; lead, 1 part ; 100 parts. 148 FO'NTAINEMOREAU'S ALLOYS. No. 2. Zinc, 91 parts ; copper, 8 parts ; lead, 1 part ; 100 parts. No. 3. Zinc, 92 parts ; copper, 8 parts ; 100 parts. No. 4. Zinc, 99 parts ; copper, 1 part ; 100 parts. No. 5. Zinc, 97 parts ; copper, 2J parts ; cast iron, J part ; 100 parts. No. 6. Zinc, 97 parts ; copper, 3 parts ; 100 parts. No. 7. Zinc, 99J parts; cast iron, j- part; 100 parts. No. 8. Zinc, 91 J- parts ; copper, 8 parts ; cast i iron, J part ; 100 parts. The proportions stated of any of these metals may be slightly varied, so long as by such variation the alloy is not made too brittle, or too soft. For instance, the proportion of copper may be varied from about 1 part to about 12 parts, in every hun- dred ; but any greater proportion of copper than this, and less than that used in forming common brass, would make the alloy brittle. The propor- tion of cast iron may be varied from about one- quarter of a part, to about two parts in every hun- dred. The proportion of lead may be varied from about one, to about twenty-four parts in every hun- FONTAINEMOREAITS ALLOYS. 149 dred parts ; bat the presence of some third metal is necessary to produce a proper combination of the zinc and lead. Instead of pure copper, or any other of the simple metals before to be used, brass, or the other alloys formed of these metals, may be used. But where this is done, the quantity of copper and the simple metals contained in such alloys must be taken into account in calculating the relative pro- portions of simple metals which the new alloy is to contain in reference to the tables of component parts. The principal object of the addition of the small quantities of copper, cast iron, and lead to the larger proportions of zinc, is to change the manner of the crystallization of the zinc after it has been fused and set to cool. The new alloys are of a closer texture, more homogeneous, and malleable, than simple zinc, and some kinds of iron ; are less liable to oxidation, and of a much finer grain than zinc — somewhat resem- bling that of steel, especially when the allo3 r s are rolled. They are also easier filed than either zinc, copper, or brass, and the filings do not stick in and clog the file. N. B. By casting the new alloys in metallic moulds, their hardness and homogeneity is increased, 13* 150 BRONZING THE ALLOYS. and a sort of temper is imparted to them, resembling or approaching to steel. For the purpose of rendering the alloys which are of a silvery-gray colour, perfectly suitable as substitutes for copper, bronze, brass, and other metals, the colour proper to the metals of which they are intended to be substitutes, is imparted to them by means of any solution of copper. The hydrochlorate of copper is found to answer best — Firstly. — For giving the alloys a blackish-bronze colour, they are treated with a solution of the salt of copper, diluted with a considerable quantity of water, and a small quantity of nitric acid may be added. Secondly. — To impart a red or copper colour, add to the solution of salt of copper, liquid ammonia, and a little acetic acid. The salt of copper may be dissolved in the liquid ammonia. Thirdly. — To impart a brass, or antique bronze colour, either of the three following means may be adopted : 1. A solution of copper, with some acetic acid. 2. The means before described for copper colour, with a large proportion of liquid ammonia. 3. Water acidulated with nitric acid, by w T hich beautiful bluish shades may be produced. It must be observed, however, that this last process can only BRONZING THE ALLOYS. 151 be properly employed on the alloys which contain a portion of copper. In either of these methods of colouring, a solution of sal-ammoniac may be substituted for the liquid ammonia. The quantities of each ingredient have not been stated, as these depend upon the nature of the alloy, the shade or hue desired, and the dura- bility required. The blackish-bronze colour may be superadded to the reel or copper colour, whereby a beautiful light colour is produced on the prominent parts of the article bronzed, or on the parts from which the blackish-bronze colour may have been rubbed off. These new alloys may be used as substitutes for various metals now in general use, such as iron, in various parts of machinery ; iron, lead, tin, or cop- per, in pipes and tubes, and bronze, brass, and cop- per, in machinery and manufactories, as well as for most of the other purposes for which more expensive metals are employed. 152 ON COVERING IRON WITH ZINC. ON ZINC AS A PROTECTIVE COVERING FOR IRON ; AND THE ADAPTATION OF THE PROCESS OF ELECTRO- DEPOSITION FOR THAT PURPOSE. BY F. PELLATT, ESQ. Read at the Institution of Civil Engineers, London. The object of this paper is to direct attention to the properties of zinc as a protecting coating to iron; to describe the processes already employed for this purpose ; the reason of their failure ; and the peculiar adaptation of the electro-deposition of the metal for the end desired. It would be a needless waste of time to say any- thing regarding the superior value of iron as a ma- terial ; but a few remarks respecting its chemical influences may not be misplaced. The cause of iron becoming corroded is its superior affinity for oxygen. If the iron and water are both pure, this is not, indeed, found to be the case ; but under ordinary circumstances, neither of these exist in a state of purity. The iron, therefore, owing to its own impurity, and that of the water, is subject ON COVERING IRON WITH ZINC. 153 to a powerful destructive influence, which is best known to those most experienced in its use ; and there is no circumstance in which we can place iron to be free from the action of water, it being present in the air and earth. So powerfully is this metal affected in the earth, or in contact with some salts, that it loses all its essential properties, and is converted into a substance so soft that it may be scratched by a finger nail. These facts render it of the utmost importance that some means be obtained for its protection, which, at the same time, will not interfere with the natural properties of the iron. The substances hitherto used for protecting iron are tin and paint. These, as lasting coatings, are not effective. The tin being electrically negative to the iron, renders it a means of destruction, instead of protection, when any part of the iron is exposed. By the laws of electricity, when metals are in con- tact, the negative metal is protected at the expense of the positive. Circumstances, such as different chemical men- strua, may alter the relative electrical states of metals. But under all ordinary circumstances this rule holds good ; and zinc being the positive metal, it becomes, in consequence, a protector to the nega- tive metal, iron. This electrical property of zinc in 154 ON COVERING IRON WITH ZINC. connexion with iron and other metals, has induced those to "whom it was known, to recommend it as a coating. The difficulty hitherto has been the ob- taining of zinc pure, and the application of it with- out injuring the texture of the iron. From the known qualities of zinc, it has been lately much employed for various purposes, but has entirely disappointed the expectations formed from its properties. The reason of this is, that no zinc of commerce is pure, and that the impurities existing are destructive to it, from the electrical law we have alluded to. The impurities existing, more or less, in all zinc, are lead, iron, arsenic, and one or two other metals, all of which are electrically negative to zinc ; the consequence being that every atom of impurity, in connexion with the zinc, forms a galvanic battery of many thousands, or rather millions, of pairs of plates, the impurities being pro- tected, and the zinc destroyed. It has no doubt surprised many who have made use of zinc, to find it in a few weeks or months, according to circumstances, perforated with small holes, and completely destroyed. We say according to circumstances, because the ordinary time zinc lasts depends not only on the amount of impurities contained in it, but also on the exciting fluid to ON COVERING IRON WITH ZINC. 155 which it is subjected. Exposed to the action of water from the atmosphere, the destructive influence operates comparatively slowly ; but with more ex- citing fluids very rapidly. Thus, a roof erected in the neighbourhood of a vinegar distillery, was completely destroyed in six weeks; and vessels used for dairy purposes have lasted but a very short time, owing to the presence of acids — these causing a rapid galvanic action be- tween the zinc and its imparities. It is then quite evident that impure zinc, being itself valueless, can- not afford protection to any other metal. Now, the only process yet in use for the purpose of coating iron with zinc, is that of immersing the iron in melted zinc. This we conceive open to many objections. The iron by this process being raised to a temperature of at least 800°, causes it to combine with the zinc, form- ing an alloy on the surface, which changes its state, and becomes brittle. But upon this subject, we shall refer to the report made by M. Dumas to the French Academy. He says — " The zincing of iron, made by steeping iron in a bath of melted zinc, has many inconveniences ; be- sides, the iron combining with the zinc, constitutes a very brittle, superficial alloy. The iron loses its tenacity — a circumstance which is not perceived, 156 ON COVERING IRON WITH ZINC. however, except in trying to zinc fine iron wire, or very thin plate. Besides, the surface, being covered with a layer of not very fusible metal, is always in- formed. Thus, fine iron wire cannot be zinced by this process, as it becomes fragile and deformed; bullets cannot be zinced, as. they become misshapen, and no longer of the same calibre." We have reason to believe that very nice manipu- lations, and annealing the iron after zincing, may remove some of M. Dumas' objections to this pro- cess. Still, two fatal objections, in our opinion, would exist to its use : first, the impossibility of ob- taining pure zinc, except at an enormous expense, the only process being sublimation or distillation; and secondly, the impossibility of retaining its purity, during the process of applying it to iron. Setting aside the fact of an alloy of iron and zinc being produced by the action of heated iron immersed in melted zinc, the presence of foreign matter neces- sary to retain the zinc in fusion, renders it impure ; these matters forming less fusible compounds, and zinc being very volatile, a great amount of waste is created. But it is well known to all those acquainted with the deposition of metals from soluble salts by the electro process, that pure metal only is deposited ; ON COVERING IRON WITH ZINC. 157 so that this process is not open to the objection upon this head, which may be made to every other, more especially in treating a metal of so intractable a character as zinc. It is also applicable to all sizes and shapes of work, requires no expensive erections, and, what is important in large operations, may be performed anywhere, and by any person. Although the protecting influence of zinc (we of course speak of pure zinc) upon other metals is practically unknown, it has been well known to men of science ; and we shall take the liberty of quoting the opinions of some of the best chemists upon the subject ; bearing in mind that zinc is electrically positive to other metals, and as such protects them from oxidation at a very trifling loss to itself — and that, by a well known law of electrical science, one body being electrically excited, that body induces its opposite state in other bodies with which it is in contact. Keeping these three points in view, we would call attention to the following opinions : — Dr. Kane says, " Zinc preserves the other metals, even if it be iron, from oxidation ;" and, again, " Zinc, when exposed to the air even in presence of water, becomes covered with a varnish of a gray substance, probably a definite sub-oxide, which is not further 14 158 ON COVERING IRON WITH ZINC. altered by exposure." Professor Graham, alluding to iron in water, says, " Articles of iron may be completely defended from the injury occasioned in this way, by the more positive metal zinc, while the protecting metal itself washes away slowly;" and further, when speaking of zinc, " When exposed to air, or placed in water, its surface becomes covered with a gray film of sub-oxide, which does not increase ; and this film is better calculated to resist both the mechanical and chemical effects of other bodies than the metal itself, and preserves it." And Professor Daniel, in his new work, says, " That a plate of pure zinc, when immersed in water, speedily becomes dulled by the formation of a thin coat of oxide ; but the oxidation proceeds no further, be- cause the adhesion of the metal prevents a renewed contact of the metal and the water." From these authorities we notice that pure zinc has a double protecting influence, the iron being protected by the zinc, and the zinc by its own oxide, besides that peculiar galvanic influence induced by the positive state of the zinc with respect to the iron. With regard to the peculiar adaptation of the electro processes to the zincing of iron, we shall again quote from M. Dumas' Report. He says, " Manufacturers, and those concerned in military ON COVERING IRON WITH ZINC. 159 affairs and the fine arts, will learn with interest that these processes enable us to zinc, in an economical manner, iron, steel, and cast iron, by means of the pile or battery, with the solution of zinc, by operat- ing without heat, and consequently not interfering with the tenacity of the metal ; by applying it in thin layers, and by thus preserving the general forms of the pieces, and even the appearance of their minutest details. The thinnest plate may receive this preparation without becoming brittle, and may be turned to account in roofing buildings." We hope these authorities fully support what we have asserted, that pure zinc affords a perfect pro- tection to iron, is not itself susceptible of rapid de- cay, and is easily applicable to the electro process. We are aware that other opinions upon this subject have been given ; some have almost denied its gal- vanic influence, and have reduced it to what they term a mere " tendency" whilst others have much overstated it. Effects which may be witnessed every day, prove that there is a secret galvanic agency at work when metals are in contact. Take, for in- stance, the decay of iron when in contact with lead. Every one has observed that iron railings let into stone work with lead, are much decayed within a 1G0 ON COVERING IRON WITH ZINC. short space of the contact of those two metals, "while the remaining portion is comparatively sound. This effect is from the iron being positive to the lead, Which is therefore protected at the expense of the iron. It is matter of regret that zinc cannot be used with the same protecting property to articles in use at sea. This arises from its strong affinity for muriatic acid, thereby forming muriate of zinc, which being readily soluble is taken off" by the water, leaving a new sur- face of zinc to be acted on, thus rapidly destroying the zinc. In situations where the articles are not exposed to the run of salt water, the zinc will be found a protection. The zinced iron solders readily. All other metals may be treated by this process for ornamental pur- poses. Copper will be found very useful. The de- positions by alkaline solutions are perfectly firm, and not subject to the objection to which those made by acid solutions are: these being always insecure from the formation of an oxide upon the iron, in- duced by the acid of the solution. The deposited Copper may be bronzed or gilt, and will be found most useful for ornamental work. ON COVERING IRON WITH ZINC. 1G1 Many specimens of zinced iron, some of which had been exposed to the action of the weather for months, were exhibited to the meeting, as well as specimens of iron coated with copper by the same process. 14* 162 WATER IN PIPES. WATER IN PIPES. This table shows the quantity and weight of water contained in one fathom of length of pipes of different bores from 1 inch to 12 inches in diameter, advancing by J inch. The weight of a cubic foot of water is taken at 1000 ounces avoirdupois, and the imperial gallon at 10 lbs. Diameter in Quantitjr in Quantity in Im- Weight in lbs. inches. Cubic inches. perial gallons. Avoird. 1 2" 14.14 0.051 0.51 1 50.55 0.205 2.05 n 127.23 0.400 4.00 2 220.19 0.818 8.18 2| 353.43 1.278 12.78 3 508.94 1.841 18.41 SJ 092.72 2.500 25.00 4 904.78 3.272 32.72 4J 1145.11 4.142 41.42 5 1413.72 5.113 51.13 6J 1710.00 0.187 01.87 6 2035.75 7.303 73.03 8J 2389.18 8.041 80.41 7 2770.88 10.022 100.22 71 3180.80 11.505 115.05 8 3019.11 13.090 130.90 6J 4085.04 14.777 147.77 9 4580.44 10.507 105.07 Q 1 5103.52 18.459 184.59 10 5054.87 20.453 204.53 101 0234.49 22.550 225.50 11 0842.39 24.748 247.48 ih 7478.50 27.049 270.49 12 - 8143.01 29.452 294.52 ON CRUCIBLES. 163 ON CRUCIBLES. The manufacture of crucibles is a branch of the potter's art, requiring great care to insure success ; and until lately, was at the best a very uncertain process. The chief requisites in a good crucible are, refractoriness in the strongest heats, capability of withstanding the corrosive effects of any substances that may be ignited in them, and the effects of sud- den alterations of temperature. They must also be composed of a material sufficiently solid in its texture to prevent the passage of the solid metal through its pores. The composition producing pots of the best qua- lity is formed by pure fire clay mixed with finely ground cement of old crucibles, to which is added a portion of black lead or plumbago. The clay is pre- pared in the same manner as observed in pottery generally. The vessels, after being worked to the proper conical shape, are slowly dried, and then baked in a kiln. The composition used in the Royal Foundry of Berlin is formed of eight parts in bulk of Stour- bridge clay and cement, five of coke, and four of 164 ON CRUCIBLES. graphite or plumbago. Crucibles manufactured from this mixture are capable of withstanding the greatest possible heat in which wrought iron melts, being equal to from 150° to 155° Wedgewood. They also bear sudden cooling without cracking. In the Ber- lin foundry they have been employed for twenty- three consecutive meltings of seventy-six pounds of iron each, which perhaps is the most complete and trying test that could be adopted. Another composition is as follows : — 8 pounds Stourbridge clay, 4 pounds burned clay cement, 2 pounds coke powder, and 2 pounds pipe clay ; the whole being compressed in moulds while in a pasty state. The Hessian crucibles from Great Almerode and Epterode, resist the action of fluxes, and are tole- rably lasting. They are made from a fire clay con- taining a small amount of iron, but no lime. This is incorporated with silicious sand. These crucibles are rather porous, but they resist the effect of saline and leaden fluxes, and are not liable to crack, but they melt below the fusing point of bar iron. The black lead crucibles bear a much higher heat. Their composition is two parts of graphite and one of fire clay; this is mixed into a pasty mass by means of water. The crucibles are baked slightly ON CRUCIBLES. 105 in the kiln, but are not completely hardened until put in the furnace for use. They are of a smooth surface, and are consequently suitable for gold and the precious metals generally. These crucibles are perhaps the very best yet manufactured, and many of the brass founders throughout Europe, and, for aught I have yet seen to the contrary, all the brass founders of America, are adopting them in pre- ference to ordinary clay ones. Mr. Anstey's patent process for the manufacture of crucibles is as follows : — 2 parts of finely ground raw Stourbridge clay, and 1 part of the hardest gas coke, previously pulverized, and sifted through a sieve of one-eighth of an inch mesh, are mixed well together with water. This mixture is moulded on a revolving wooden block, somewhat similar to the process pursued in pot throwing, a gauge being used to regulate the thickness of the pot, and a cap of linen placed upon the core previous to the appli- cation of the clay, in order to prevent its adhering when removed. The pot is then dried in a gentle heat, and is not thoroughly completed until required for use. It is then warmed before a fire, and laid in the furnace, with the mouth downwards — the heat of the fire having been previously lowered by the application of fresh coke. It is gradually brought ]66 PLUMBAGO. up to a red heat, reversed, and fixed in its proper position in the furnace, and is then ready to receive the charge of metal. PLUMBAGO. Plumbago, or black lead, of which pencils are made, is a compound of iron and carbon, in the pro- portion of 9 parts carbon to 1 of iron. It has nothing similar to lead about it, unless its inquinat- ing property, by which paper is so readily marked. In this combination we have a metallic alloy less cohesive than almost any other substance, mercurial amalgam excepted ; whilst the very same ingredients, in different proportions, produce another alloy, steel, which has properties diametrically opposite, as it is capable of cutting the hardest substances, with very few exceptions. The softest steel is harder than the hardest iron. HARDENING STEEL. 167 HARDENING STEEL. The process of hardening steel is called temper- ing or attempering, and consists in that novel ar- rangement of the particles which is produced when steel, while hot, is plunged into cold liquids, as water. The colder the liquid, or the more sudden the operation of cooling, the harder will the steel be. Case-hardening is the superficial conversion of the surface of iron into steel, by heating it in contact with animal carbon, in close vessels. Bar iron is converted into steel in the same way, only that powdered charcoal is the substance in which it is imbedded. ON BORON. This is the basis of a substance which has been long and extensively used in the arts and in medi- cine, under the name of borax. It is found abund- antly in Thibet and in South America, but in a JG8 ON BOEON. state too impure to be used without refining. This was long a secret process practised by the Venetians and Dutch, who imported the crude salt into Europe, under the name of tincal. Borax has a sweetish taste, and is " soluble in twelve parts of cold, and two parts of boiling water." Its crystals are transparent, but effloresce and be- come opaque in a dry atmosphere ; and they appear luminous by friction in the dark. It melts at a heat a little above that of boiling water, and gives out its water of crystallization, after which it forms a spongy mass, well known as calcined borax. When further heated to ignition, it passes into a glassy-looking substance, known as glacial borax. Boracic acid is obtained in unlimited quantity from the lakes of Tuscany. The water requires simply to be evaporated until the acid solution has been sufficiently concentrated to afford crystals. The acid thus obtained is chiefly taken to M. Pay en's works, at Marseilles, where it is manu- factured into borax. Dry borax, at a high temperature, has the re- markable property of melting and vitrifying the metallic oxides into glasses of different colours. On this account it is a most useful reagent for the blow- ON BORON. 169 pipe. With oxide of chrome it forms an emerald green glass, and with oxide of cobalt an intensely blue glass. Oxide of copper tinges it pale-blue ; oxides of iron, bottle-green ; oxide of tin, opal ; oxide of manganese, violet ; oxide of nickel, pale yellowish-green. With the oxides of silver and zinc, and with several of the earths, it forms white enamels. Borax, in consequence of this property of vitrify- ing the metallic oxides, is used to clean the surface of metals, in processes of soldering with hard solder, and of welding cast steel. It is also valuable in the fusion of metals to pro- tect their surface from oxidizement. And it is worthy of remark, that, when mixed with shell-lac, in the proportion of one part to five, borax renders that resinous substance soluble in water, and forms with it a species of varnish. 15 170 ON SULPHUR. ON SULPHUR. This element, popularly known as brimstone, stands sufficiently well characterized by its brittle- ness, non-metallic appearance, and peculiar yellow colour. As a combustible it is universally known. Exposed to a temperature of 218° it melts almost into a liquid. When heated a few degrees higher, it becomes tenacious ; and when heated to the tem- perature of 800°, it takes fire, burns away with a lambent blue flame, and leaves no residuum. As the temperature rises the flame becomes more white ; and in pure oxygen gas the combustion goes on with great brilliancy. If, while melted and viscid, sulphur be poured into cold water, it acquires somewhat the consist- ency of soft sealing-wax, and in this state it is very commonly used for taking impressions, from seals and medals. Native sulphur is brought into this country chiefly from Sicily, where it occurs in beds of a blue clay formation, occupying the central half of the south coast of the island, and extending inwards as far as the district of Etna. ■ Sulphur is also an abundant ingredient in various minerals : iron pyrites and ON SULPHUR. 171 galena, sulphurets of iron and lead, are particularly abundant in some localities ; and at one time a large portion of the sulphur used in England was obtained from the copper pyrites of the mines of Anglesey. It was, however, less pure than the fine sulphur of Sicily, and other volcanic districts, being commonly mixed with arsenic and other metallic impregnations, which are difficult to separate. Sulphur is sometimes employed for cementing iron bars into stone ; and at present it is in repute for taking impressions of seals and cameos. When used for this purpose, it is commonly kept previously melted for some time, to give the casts the appear- ance of bronze. The principal consumption of it, however, is in the manufacture of sulphuric acid, gunpowder, and vermillion. When the end of a sulphur match is lighted, the flame emits copious fumes, which are a compound of oxygen and sulphur. These fumes are intensely acid to the taste ; they constitute what is called sul- phurous acid, the first of the combinations of sul- phur and oxygen. The gas has a strong affinity for the water, and the solution which it forms with it is known as liquid sulphurous acid. This, if left ex- posed to the air, absorbs more oxygen, and passes into sulphuric acid. 172 SELENIUM. Sulphur also combines with hydrogen, forming the highly poisonous and offensive gas known as sul- phuretted hydrogen, and which not unfrequently contaminates the coal gas supplied to us for illumi- nation. Sulphur and carbon also combine, and form a beautifully transparent and colourless liquid, ex- ceedingly volatile, and giving off an odour the most foetid and nauseous which it is possible to conceive. Sulphur likewise enters into combination with metals, forming sulphurets, and is a most excellent flux in the making of brazing solder. SELENIUM. This is a rare elementary substance, nearly allied to sulphur in its properties, although it in some re- spects partakes of the nature of a metal. It was discovered by Berzelius, in 1817, in the refuse of an oil of vitriol manufactory, where it was derived from the iron pyrites employed in the works, and which contain a mixture in very minute proportions of a similar compound of selenium and iron. It has also been found sparingly in combination with seve- ON CHLORINE. 173 ral other metals, as lead, cobalt, copper, and bis- muth ; and with sulphur, in the volcanic products of the Lipari Islands. It is separated from its combinations with diffi- culty, and hitherto only in minute quantities. When obtained free of admixture, selenium, at common temperatures, is brittle, solid, of a reddish-brown colour, and metallic lustre, without taste or smell. But when finely powdered the powder assumes a deep-red, inclined to purple. It softens at the tem- perature of 180° ; is pasty at 200°, and melts at a few degrees above the boiling point of water. When warm it exhales a strong odour of decayed horse- radish, and is so ductile that it may be drawn into threads, which are red by transmitted, but gray by reflected light. It boils at 600°, and in close vessels throws off deep-yellow vapours, which condense into black, metallic-looking drops. ON CHLORINE. Chlorine enters into numerous highly important and interesting combinations. Various bodies, when immersed in it when in a liquid state (that is, when, 15* 174 ON CHLORINE. submitted to a pressure of four atmospheres, it be- comes a yellow transparent liquid), take fire sponta- neously. A candle burns in it with a red flame, and a piece of phosphorus introduced into it, burns with a pale-white light. Copper, tin, zinc, antimony, and arsenic, when introduced into it in their leaves, or reduced to filings, take fire, and, combining with the gas, form compounds analogous to the oxides, and which are therefore called chlorides. Mercury also enters rapidly into combination with it, forming chloride of mercury, a substance better known as corrosive sublimate. The grand source of chlorine is the water of the ocean. This is an enormous solution of salt — a universally known and indispensable article of con- sumption with the human race ; an article, indeed, which seems to be essentially necessary to maintain the body in a healthy condition. Now this salt is a compound of chlorine and a metal. It is, in fact, a chloride, consisting, when pure, of 60 of chlorine, and 40 of sodium, in 100 parts; and whether it be obtained by evaporation of sea water, or be dug out of the salt mines of Wieliczka or North wich, it has the same composition. METALLIC OXIDES. 175 Some of the minerals contain but one earth ; but minerals are found in which the earths are combined in different proportions, by processes which produce that apparently endless variety of objects which mineral nature presents for our contemplation. Science has of late years demonstrated that none of the earths are simple substances, that is, chemical elements. Sir Humphrey Davy has proved that none of them are entitled to that character, that they are in fact compounds of certain metals with oxygen — that is, metallic oxides. This has been shown by the very direct method of abstracting oxygen from them, and thereby separating the me- tallic base. Thus, alumina (being the basis of alum) is the oxide of a gray and hard metal like platinum, and which burns with great brilliancy when heated with access of air, and reproduces the earth by ab- sorption of oxygen from the atmosphere. It is very singular that soda, as distinguished from potash, has been known with us only of late years ; whereas it was familiar to the Greeks and Hebrews. It was also known in Egypt, where it is found na- tive, and is known by the name of natron — which 176 METALLIC OXIDES. occurs in the Bible. Thus Jeremiah speaks of wash- ing in natron.* From the preceding summary we may reckon ourselves justified in concluding that the solid strata of our globe — that is, the superficial shell with which we are acquainted, if not the vast mass of the globe itself — are nothing more than masses of metals of different kinds, disguised by oxygen : that they are in fact oxides, and bear evidence, in many cases, of being the products of combustion. * Jeremiah, ii. 22. APPENDIX. (177) AN APPENDIX USEFUL AND VALUABLE RECEIPTS. TO BROWN GUN BARRELS. Take of nitric acid, half an ounce ; sweet spirit of nitre half an ounce ; blue vitriol, two ounces ; tincture of steel, one ounce. Mix all together in eight gills of water. Apply this mixture with a sponge, then heat the barrel a little, and move the oxide with a hard brush. This operation may be repeated a third and fourth time, till you have the brown required. It is then to be carefully wiped, and sponged with boiling water, in which there has been put a small quantity of potass. The barrel being taken from the water, must be made perfectly dry, and then rubbed smooth with a burnisher of hard wood ; afterwards heated to the height of boiling water, and varnished with the following varnish : — (179) 180 VARNISH FOR GUN BARRELS. Varnish for gun barrels that have undergone the process of browning. Take of spirits of wine two parts, dragon's blood, powdered, three drachms ; shell-lac bruised, one ounce ; dissolve all together. This varnish being laid on the barrel, and become perfectly dry, must be rubbed with a burnisher to render it smooth and glossy. ETHEREAL SOLUTION OE GOLD. Saturate nitro-hydrochloric acid with pure gold. Crystallize, and with the crystals saturate water. Shake this aqueous solution in a phial with an equal volume of pure ether ; then two fluids will result, the lighter of which is the ethereal solution of gold, and may easily be separated. This must be kept in a darkened bottle, as by exposure to light it quickly decomposes, flakes of gold being deposited. Any substance moistened with this will receive a coating of metallic gold, and hence metals may be rendered not liable to corrosion. Even in the dark it cannot be preserved long, but undergoes slow decomposition. TINNING. 181 TO COAT SMALL NAILS, ETC., WITH TIN. Put half an ounce of powdered tin (which may be procured of any operative chemist), into a com- mon Florence flask, pour on about two ounces of concentrated muriatic acid, and boil over a spirit lamp until the tin is dissolved. When cool, pour into any convenient vessel and dilute with about an equal bulk of pure water. Drop in the nails required to be coated, holding the vessel so that they may all fall to one side. Immerse a piece of sheet-copper into the solution, as far apart from the nails as pos- sible, and connect it with the latter by means of a piece of copper wire. The effect of this arrange- ment is the developement of a current of voltaic electricity, which causes a rapid decomposition of the fluid, and the deposition of tin on the surface of the nails. After being subjected to this treatment for about an hour, the nails will be found to have re- ceived a thick coating of metal, and may then be removed from the liquid, dried, and polished. Recourse is frequently had to the above process for the purpose of coating the nibs of steel pens with tin, in order to prevent them from rusting. It succeeds better than any other method ever tried. 16 182 BRONZING ELECTROTYPE CASTS. BRONZING ELECTROTYPE CASTS. Chemical Bronze. There are many modes of bronzing employed in the arts ; the intent of each is to bring out the work- manship of the object. The selection is entirely a matter of taste. To prevent too great a sameness of appearance in a cabinet, it is, perhaps, better not to confine oneself to a solitary method. A chemical bronze may be made by boiling two ounces of carbonate of ammonia with one ounce of acetate of copper, in half a pint of vinegar, till the vinegar is nearly evaporated. Into this, pour a solution consisting of sixty-two grains of muriate of ammonia, and fifteen grains and a half of oxalic acid, in half a pint of vinegar. Replace the vessel on the fire till the contents boil ; when cold, strain through filtering paper ; preserve the liquor for use. The remaining sediment may be again treated with another half pint of the solution. This preparation must only be applied to medals bright and clean. Dirty specimens may be polished by an article used in domestic economy, consisting of rotten- stone, soft soap, and water. The medal is to be BRONZING ELECTROTYPE CASTS. 183 well rubbed with a hard brush dipped in this. Care must be taken not to scratch the medal. It must afterwards be washed in water and placed to dry; when dry, the application of the leather and plate- brush will produce the required polish. Medals may also be cleansed by dipping them in nitric acid, either concentrated or diluted. Wax and grease may be removed by boiling in pearl-ash and water, or by pouring the boiling ley on the medals. In applying the bronze, first warm the medal, then dip a camel-hair pencil into the liquor and brush the surface for half a minute ; immediately after, pour boiling water over it. Directly the medal is dry, rub its surface lightly with soft cotton very slightly moistened in linseed oil. Gentle friction with a piece of dry cotton will finish the operation. The colour produced by this means is red ; its tints vary according to circumstances. Medals bronzed thus must be examined occasionally before they are con- signed to the cabinet ; for if perchance the vinegar has not been perfectly washed away, they will be disfigured by the formation of a green powder, — the acetate of copper. Should this occur, it may be removed by means of the moist and dry cotton. 184 BLACK LEAD BRONZE. BLACK LEAD BRONZE. A very beautiful bronze is obtained bj the simple application of plumbago. It is obtained in a few minutes, and with very little trouble. The tint ob- tained seems much to depend on the state of the surface of the original medal. Copies of some medals "take" the black lead better than those of others. To produce the tint in the greatest perfec- tion, the operation should be performed immediately after the medal is separated from the mould. Bright specimens from fusible moulds are best, but all others may be thus treated ; those taken from wax should be cleansed with pearlash or soda. The bronze is obtained by brushing the surface of the medal with plumbago, then placing it on a clear fire till it is made too hot to be touched, and applying a plate brush so soon as it ceases to be hot enough to burn the brush. A few strokes of the brush will produce a dark brown polish, approaching black, but entirely distinct from the well known appearance of black lead. If the same operation is performed on a medal that has been kept some days, or upon one that has been polished, a different, but very brilliant tint is produced. The colour is TO TIN IRON. 185 between red and brown. The richness of colour thus produced is by many preferred to the true dark brown. CARBONATE OF IRON BRONZE. Beautiful tints are produced by using plate- powder or rouge. After moistening with water, it is applied and treated in precisely the same manner as the plumbago. TO TIN IRON. Metal to be tinned must be cleansed, if new work, by putting it in a pickle — a mixture of sulphuric acid and water — then scoured with sand, and cleansed in water : but if old, the pickle should be a mixture of muriatic acid and water. It is then ready for tinning. The article should be placed on the fire, and suf- ficient heat applied to melt the tin. Care should be taken that too great a heat should not be applied, or the article will be burned. It must be rubbed well 16* 186 LIQUID GLUE AND FIRE-CLAY. with a piece of sal-ammoniac placed between two wires, likewise some powder sprinkled upon it, to keep the metal from oxidating. Apply the tin, wipe it over with a piece of tow, then the work is finished. LIQUID GLUE. Shell-lac dissolved in wood naptha (the pyroxilic spirit of the chemists, and the naptha of the oil and colour shops) makes good liquid glue, water-proof, and not requiring the application of heat. A quarter of a pound avoirdupois of shell-lac to be dissolved in three ounces of naptha, apothecaries' measure. Put the former into a wide-mouthed bottle ; pour the latter upon it, and stir the mixture two or three times during the first thirty-six hours. ARTIFICIAL FIRE-CLAY. The fusibility of common clay arises from the pre- sence of impurities, such as lime, iron, and magnesia. These substances may be easily removed by steeping A VALUABLE CEMENT. 187 in hot muriatic acid, then washing with water, and drying. Excellent crucibles may be made from common clay prepared in this manner. A CEMENT WHICH RESISTS THE ACTION OF FIRE AND WATER. Take half a pint of milk, mix with it an equal quantity of vinegar, so as to coagulate the milk ; separate the curds from the whey, and mix the lat- ter with the whites of four or five eggs, well beaten up. The mixture of these two substances being complete, add to them quick-lime, which has been passed through a sieve ; make the whole into a thick paste, to be of the consistence of putty when used. This cement has been applied to close the fissure of an iron cauldron for the boiling of pitch, and which has been in use for five years without requir- ing further repairs. 188 CEMENT FOR THE JOINTS OF CAST IRON. CEMENT FOR THE JOINTS OF CAST IRON. Take of cast iron borings, 20 pounds ; flour of sulphur, 2 ounces ; muriate of ammonia, 1 ounce ; mix intimately in the dry state, and then add a suf- ficient quantity of warm water to render the whole quite wet. Press the mass together in a lump, and allow it to remain until such time as the combined action of the materials renders it quite hot, in which state it must be hammered, with proper tools, into the joints. NIELLO-METALLIC ORNAMENTS. Cover the object to be ornamented with an etch- ing ground similar to that employed by copper-plate engravers ; draw the ornament with a needle, and etch it by means of a corrosive acid ; then carefully remove the etching ground with the proper dissolv- ing fluids (such as oil of turpentine, ether, &c), and afterwards wash the object quite clean, and set for NIELLO-METALLIC ORNAMENTS, ETC. 189 a moment with a weak acid. Place it now in a gal- vano-plastic apparatus, and leave it until it becomes galvano-plastically covered, that is, all the etched lines filled up. When all the lines and cavities are completely filled up in this way, and the deposit in them is 'equally high as, or yet higher than, the plain surface, the object must be taken out of the galvano-plastic apparatus, and the metallic layer, which has been raised by the operation, ground or planed off until brought to the same level with the metal of the object, leaving the etched lines or cavi- ties full. Of course, the metal of the object to be orna- mented and the metallic deposit must be different. The effect produced is extremely pretty, and the means cheap and simple. TRACING PAPER. Mix six parts (by weight) of spirits of turpentine, one of resin, one of boiled nut oil, and lay on with either a brush or sponge. 190 TO FIX DRAWINGS. TO PIX DRAWINGS. A method which is equally simple and ingenious, of giving to drawings in pencils and crayons the fixidity of painting, and without injury, is obtained by spreading over the back of the paper an alcoholic solution of white gum-lac. This solution quickly penetrates the paper, and enters even into the marks of the crayon on the other side. The alcohol rapidly evaporates, so that in an instant all the light dust from the crayons and chalk, which resembles that on the wings of a butterfly, adheres so firmly to the paper, that the drawing may be rubbed and carried about without the least par- ticle being effaced. The following are the accurate proportions of the solution : 10 parts of common gum-lac are dissolved in 120 parts of alcohol ; the liquid is afterwards bleached with animal charcoal. For the same purpose may be used even the ready- made paint that can be purchased at the colour stores, containing a sixth of white-lac, and adding two-thirds of rectified spirits of wine. After it has been filtered, there is nothing further to be done USEFUL RECEIPTS. 191 than to spread a layer of either of these solutions at the back of the drawing, in order to give them the solidity required. ANTIDOTE TO ARSENIC. Magnesia is an antidote to arsenic, equally effi- cacious with peroxide of iron, and preferable to it, inasmuch as it is completely innocuous in almost any quantity, and can be procured in any form. TO SOFTEN IVORY. Slice half a pound of mandrake and put it into a quart of the best vinegar, into which immerse your ivory. Let it stand in a warm place for 48 hours, and you will then be enabled to bend the ivory into any required form. TO SEPARATE THE METALLIC PORTION FROM GOLD AND SILVER LACE. Immerse the lace for a short time in nitric acid. ]92 BLUEING AND GILDING STEEL. BLUEING AND GILDING STEEL. The mode employed in blueing steel is merely to subject it to heat. The dark blue is produced at a temperature of 600°, the full blue at 500°, and the blue at 550°. Steel may be gilded by the following process : to a solution of the muriale of gold, add nearly as much sulphuric ether. The ether reduces the gold to a metallic state and keeps it in solution, while the muriatic acid separates, deprived of its gold, and forms a distinct fluid. Put the steel to be gilded into the ether, which speedily evaporates, depositing a coat of gold on the metal by dint of the attraction between them. After the steel has been immersed it should be dipped into cold water, and the burnisher should be applied, which strengthens its adhesion. Figures, flowers, and all descriptions of ornaments and devices, may be drawn on the steel by using the ether with a fine camel-hair pencil, or writing pen. TO HARDEN STEEL DIES. 193 TO HARDEN STEEL DIES. A vessel holding 200 gallons of water, is to be placed at the height of 40 feet above the room in which the dies are to be hardened. From this vessel the water is conducted through a pipe of one inch and a quarter in diameter, with a cock at the bottom, and nozzles of diiferent sizes to regulate the dia- meter of the jet of water. Under one of these place the heated dies, the water being directed on to the centre of the upper surface. By this process the die is hardened in a way as best to sustain the pressure to which it is to be subjected; and the middle of the face, which by the old process was apt to remain soft, now becomes the hardest part. The hardened part of the dies so managed, were it to be separated, would be found to be in the seg- ment of a sphere, resting in the lower softer part, as in a dish, the hardness, of course, gradually de- creasing as you descend towards the foot. Dies thus hardened, preserve their form till fairly worn out. 17 194 PORTABLE GLUE, ETC. PORTABLE GLUE. Boil one pound of the best Russian glue, and strain. Then add half a pound of brown sugar, and boil thick. When cold, the compound may be poured into small moulds, and afterwards cut into pieces. This glue is very soluble in warm water, and is particularly useful to artists for fixing their drawing- paper to the board. PREVENTION OF CORROSION. The best means of preventing corrosion of metals is to dip the articles first into a very dilute nitric acid, to immerse them afterwards in linseed oil, and to allow the excess of oil to drain off. By this pro- cess metals are effectually prevented from rust or oxidation. CEMENT AND SOLUBLE GLASS. 195 CEMENT. Mix ground white lead with as much finely-pow- dered red lead as will make it of the consistence of soft putty. SOLUBLE GLASS. What is called soluble glass is now beginning to come into use as a covering for wood and other practical purposes. It is composed of 15 parts of powdered quartz, 10 parts of potash, and 1 part of charcoal. These are melted together, worked in cold water, and then boiled with 5 parts of water, in which it entirely dissolves. It is then applied to wood-work, or any other required substance. As it cools it gelatinises, and dries up into a transparent, colour- less glass, on any surface to which it has been ap- plied. It renders wood nearly incombustible. 196 JAPANNING. JAPANNING. First. Provide yourself -with a small muller and stone, to grind any colour that you may require. Secondly. Prepare yourself with white hard var- nish, brown varnish, turpentine varnish, Japan gold size, and spirit of turpentine, which you may keep in separate bottles until required. Thirdly. Provide yourself with flake white, red lead, Vermillion, lake, Prussian blue, king's and patent yellow, orpiment, spruce and brown ochre, mineral green, verditer, burnt umber, and lamp- black. Observe that all wood- work must be prepared with size, and some coarser material mixed with it, in order to fill up and harden the grain of the wood — such, indeed, as may best suit the colour intended to be laid on — which must be rubbed smooth with glass-paper when dry ; but in case of accident it is seldom necessary to resize the damaged places unless they are considerable. With the foregoing colours you may match always any one in use for japanning, always observing to grind your colours smooth in spirit of turpentine ; JAPANNING. 197 add a small quantity of turpentine and spirit varnish, and lay it carefully on with a camel's-hair brush, then varnish with brown or white spirit varnish, according to colour. For a black, mix up a little size and lamp-black, and it will bear a good gloss without varnishing over. To imitate black rosewood, a black ground must be given to the wood, after which take some finely levigated red lead, mixed up as before directed, and lay on with a flat, stiff brush, in imitation of the streaks in the wood ; after which take a small quantity of lake, ground fine, and mix it with brown spirit varnish, carefully observing not to have more colour in it than will just tinge the varnish ; but should it happen on trial to be still too red, you may easily assist it with a little umber, ground very fine, with which pass over the whole of the work intended to imitate black rosewood, and it will have the desired effect. If the work be done by a good japanner, according to the foregoing rules, it will, when, varnished and polished, scarcely be distin- guished from the real wood. 17 198 TO PRESERVE POLISHED STEEL, ETC. TO PRESERVE POLISHED STEEL FROM RUST. Mix some oil with caoutchouc; melt in a close vessel, stirring to prevent burning. A high tem- perature will be required. This will form a perfect air-proof skin over the surface, which may very easily be removed by brushing with warm oil of turpentine. CEMENT FOR ATTACHING METAL TO GLASS. Take two ounces of a thick solution of glue, and mix with one ounce of linseed oil varnish, or three-quarters of an ounce of Venice turpentine. Boil together, agitating until the mixture becomes as intimate as possible. The pieces cemented should be fastened together for the space of forty-eight or sixty hours. VARNISHES. 19f VARNISH FOR COLOURED DRAWINGS. Canada balsam, one ounce ; oil of turpentine, Ho ounces. Dissolve. Size the drawings first with a jelly of isinglass, and when dry apply the varnish, which will make them look like oil paintings. JAPANNERS COPA; GARNISH. Take of the best pale African copal, seven pounds ; fuse ; add two quarts of clarified linseed oil. Boil for a quarter of an hour, remove it into the open air, and add three gallons of boiling oil of turpen- tine. Mix well, then strain into the cistern, and cover up immediately. SOFT VARNISH. Callot's soft varnish for etching: — linseed oil, four ounces ; and half an ounce each of gum benzoin and white wax. Boil to two-thirds. 200 VARNISHES. HARD VARNISH. Callot's hard varnish for etching : — Take four ounces each of linseed oil and mastic, and melt to- gether. FLEXIBLE VARNISH. Flexible varnish for balloons, &c. : — India-rubber in shavings, one ounce ; mineral naptha, two pounds. Digest at a gentle heat in a close vessel until dis- solved, then strain. FRENCH POLISH. Dissolve one part of gum-mastic, and one part of gum-sandarach, in forty parts of spirits of wine, and then add three parts of shell-lac. This process may be performed by putting the ingredients into a loosely corked bottle, and then placing it in a vessel VARNISHES. 201 of water a little below 173° Fahrenheit, or the boil- ing point of spirits of wine, until the solution be effected. BRUNSWICK BLACK. Foreign asphaltum, forty-five pounds; drying • oil, six gallons; and litharge, six pounds. Boil for two hours, then add dark gum amber (fused), eight pounds ; hot linseed oil, two gallons. Boil for two hours longer, or until a little of the mass, when cooled, may be rolled into pills. Then withdraw the heat, and afterwards thin down with twenty-five gallons of oil of turpentine. Used for iron-work, &c. MORDANT VARNISH. Take one ounce of mastic, one ounce of sanda- rach, half an ounce of gum-gamboge, and a quarter of an ounce of turpentine. Dissolve in six ounces of spirits of turpentine. 202 VARNISHES. ANOTHER. Place a quantity of boiled oil in a pan, and sub- ject it to a strong heat. When a disengagement of black smoke takes place, set it on fire, and in a few moments extinguish it, by covering over the pan. Then pour the matter while heated into a bottle, previously warmed, adding to it a little oil of tur- pentine. ANOTHER. Mix asphalte and drying oil, diluted with oil of turpentine. For bronzing, or very pale gilding. ANOTHER. Take a quantity of camphorated copal varnish, and add a little red lead. VARNISHES. 203 ANOTHER. Dissolve a little honey in thick glue. For gild- ing, &c. SUPERIOR GREEN TRANSPARENT VARNISH. The beautiful, transparent green varnish em- ployed to give a fine glittering colour to gilt or other decorated work, may be prepared as follows : Grind a small quantity of Chinese blue with about double the quantity of finely powdered chromate of potash, and a sufficient quantity of copal varnish thinned with turpentine. The mixture requires the most elaborate grinding or incorporating, otherwise it will not be transparent, and therefore useless for the purpose to which it is intended. The "tone" of the colour may be varied by an alteration in the proportion of the ingredients. A preponderance of chromate of potash causes a yellowish shade in the green, as might have been expected; and vice versa with the blue, under the same circumstances. This 204 VARNISHES. coloured varnish will produce a very striking effect in japanned goods, paper-hangings, &c, and can be made at a very cheap rate. ETCHING VARNISH. Take of white wax, two ounces ; and of black and Burgundy pitch, each half an ounce. Melt to- gether, adding by degrees two ounces of powdered asphaltum. Then boil until a drop taken out on a plate will break when cold, by being bent double two or three times between the fingers, when it must be poured into warm water, and made into small balls for use. THE END. V* A ■ *V U * a o' -.^, SEP 7 6