2.3 



UNDULATORY FORCES. ELECTRO-METALLURGY. [PI^TI.NA, ETC., sourrioio. 



connect them with about three pain of Smeo's batteries 

 the gold anode with the platinised silver by one wire, 

 and the copper cathode with the cine by another wire, 

 allowing the current to pan, until, by transferring the 

 cathode for a short time to the outer liquid, it receive* a 

 good deposit of gold, the solution being maintained at a 

 temperature of about 160 Fab. ; the liquid of the poroui 

 cell should then be transferred to the outer solution, and 

 the process stopped. The amount of gold dissolved is 

 not of material consequence provided the deposit be good, 

 a* a solution may contain from half an ounce to four 

 ounces to the gallon, and be a good depositing liquid. 



100. Gilding Solution of M. Ruolz. "Dissolve ton 

 parts of cyanide of potassium in 100 parts of distilled 

 water; ; filter it, and add one port of cyanide of gold, 

 prepared with care, well washed, and dried out of the 

 influence of light; keep the mixture in a closed glass 

 Teasel, at the temperature of 00 to 77 Fall., for two or 

 three days, out of the presence of light, and frequently 

 stir it" 



1GJ. M. BecquertFi Gilding Liquid. "Dissolve one 

 port of terchlondo of gold and ten parts of ferro-cyanido 

 of potassium in 100 ports of water ; filter the liquid, to 

 remove the separated cyanide of iron ; add 100 parts of 

 a saturated solution of ferro-cyanide of potassium, and 

 dilute the mixture with one or two volumes of water. 

 In general, the tone of the gilding varies according as 

 the solution is more or less dilute ; the colour is most 

 beautiful when the liquid is most dilute, and most free 

 fiom iron. To make the surface bright, it is sufficient 

 to wash the article in water, acidulated with sulphuric 

 acid, rubbing it gently with a piece of linen cloth." 



162. G tiding Liquids of M. Fizeau. "1st. Dissolve one 

 part of dry chloride of gold in 160 parts of distilled water ; 

 then odd, little by little, a solution of carbonate of 

 potash in distilled water until the liquid begins to become 

 cloudy; we may use this liquid immediately." And, 

 2nd, used by M. Lerebour : "Dissolve one gramme* of 

 chloride of gold, and four grammes of hyposulphite of 

 soda, in one litre of distilled water." 



163. M. LevoFt Solution for Gilding Silver." Dissolve 

 neutral chloride of gold, then add an aqueous solution 

 of sulpho-cyanide of potassium, until the precipitate first 

 formed is rodissolved. The liquid will retain a slightly 

 acid reaction ; if it lose tliis, it must be renewed by 

 adding a few drops of hydrochloric acid." 



1C4. liyM. de Eriant. " Dissolve thirty-four grammes 

 of gold in aqua regia, and evaporate the solution until it 

 becomes neutral chloride of gold ; then dissolve the 

 cldoride in four kilogrammes of warm water ; and add to 

 it 200 grammes of commercial magnesia, carefully sifted. 

 The gold is precipitated in union with the magnesia; 

 filter and wash with pure water ; digest the precipitate 

 in forty parts of water mixed with three parts of nitric 

 acid to remove the magnesia ; then wash the oxide of 

 gold remaining with water, until the wash-water ex- 

 hibits no acid reaction. Next dissolve 400 grammes of 

 forro-cyanide of potassium, and 100 grammes of caustic 

 potash, in four litres of water ; add the oxide of gold, 

 and boil the solution about twenty minutes. When the 

 gold is dissolved there remains a small amount of iron 

 precipitated, which may bo removed by nitration, and 

 the liquid, of a fine gold-yellow colour, is ready for use. 

 It may be used either hot or cold. " 



165. Formulat of M. J. L. "1st. Take thirty-one 

 grammes and twenty-five centigrammes of oxide of gold, 

 live hectogrammes of cyanide of potassium, and four 



The following table of lomc French weight*. Ac., mar be of uw to 

 the ituclcnt. We may obtcrrc, that French weight* and meaiurm hare 

 an invariable relation to the uulrt, which U equal to about 39 inchn 

 Hriliih. A gramme, which U the unit of French weight*, U equal to 

 about 1SJ grain* IlritUh, and repreaent* the weight of a cube of water at 

 40 Fan., the aides of which meuure the l-100th of a metre 



Faixn. 



'I ;. Li iri.ii.i- 



-100th of a metre each. 

 BaiTUH. 



i nearly. 



ho Gramme 151 gr 



XUogramm. (1,000 gramme.) j! K 



., Litre (1 kilogramme) 



Thb bring the unit of French liquid meaiure, equal, the weight of a 

 lube of water, each of the aide* of which mcuurc* the tenth part of a 



The Centigramme U the one-hundredth part of a gramme." 

 The lUttofTuuM 1* equal to on* hundred gramme*. 



litres of water, and boil them together half-an hour. 

 The resulting solution must be worked hot, and may be 

 used to gild copper, brass, and silver. 2nd. Dissolve 

 ten parts of forro-cyanide of potassium and one purt of 

 dry terchlondo of gold in 100 parts of water ; oxide of 

 iron will be precipitated. Boil the solution two or three 

 hours, in a porcelain or glass vessel, until a precipitate 

 collects at the bottom and the supernatant liquid is 

 transparent and of a canary-yellow colour ; filter the 

 solution, and dilute it with three times its volume of 

 water." 



166. A process or branch of trade, termed "solid 

 depositing," has of late years been gradually extending 

 itself. It consists in making solid articles of gold and 

 silver, by electro-deposition, upon gutta-percha or other 

 moulds such, for instance, as watch and clock faces, 

 ornamental snuff-boxes, and other articles elaborately 

 chased or engraved, or which have very complex or 

 under-cut ornaments upon them; the expense of multi- 

 plying these by the electro-process being less than by 

 the ordinary means. Mr. Alexander Parkes took out a 

 patent, dated March, 1841, for a solution for depositing 

 solid articles in gold. It is formed thus : Dissolve one 

 ounce of pure gold in aqua regia, and evaporate the 

 solution to dryness ; then add two gallons of water and 

 sixteen ounces of cyanide of potassium, and work the 

 resulting liquid at a temperature of about 120 or 

 130 Fan. 



167. Salts of Pltitiita. The only common salt of 

 plat ina is the bichloride: it is formed by adding]" 



of platiua foil to hot aqua regia as long as gas is evolved 

 from them ; the solution, which is then of a deep-red 

 colour, should be evaporated nearly to dryuoss, and left 

 to cooL 



168. Platina Solutions. For platinising silver by 

 simple immersion process, we may use a solution con- 

 sisting of bichloride of platiua, dissolved in water con- 

 taining one-fourth its volume of nitric acid, or wo 

 may use simply a very hot aqueous solution of tho 

 bichloride alone. Nearly all metals decompose the bi- 

 chloride solution, and become coated with platina in it by 

 simple immersion. For the battery process wo may use 

 solutions of the iodide, bromide, or bichloride, or the 

 double chloride of platina and sodium. The solution of 

 the double chloride of platina and sodium is mado by 

 dissolving one equivalent (1697 parts) of bichloride of 

 platina and one equivalent (68 '5 parts) of common salt, 

 in water ; it requires a small anode of platina and a 

 very weak battery to obtain a regulino deposit. A good 

 solution for depositing reguline platina may also be mode 

 by dissolving bichloride of platina and common salt in a 

 solution of caustic potash. 



169. Palladium Solution*. A solution of double cya- 

 nide of palladium and potassium may be used for de- 

 positing palladium. It may be made by chemical m. 



by dissolving palladium in nitric acid, precipitating the 

 solution by a solution of cyanide of potassium, washing 

 the precipitate, and dissolving it in a solution of cyanide 

 of potassium to saturation, and then adding a little free 

 cyanide ; or it may be easily made by the battery pro- 

 cess, bypassing a current through a large palladium 

 anode in a solution of cyanide of potassium, until a clean 

 smooth cathode receives a good deposit. This is au ex- 

 cellent solution for depositing reguline metal; it acts 

 upon tho anode with uncommon energy, conducts freely, 

 and deposits plenty of reguline metal : a thin deponit of 

 palladium obtained in this solution has been used for 

 fixing Daguerreotype pictures, instead of gold, and is 

 said to give them a finer tone. 



170. Selecting Practical Liqtiidt. Having enumerated 

 nearly all the solutions which have been used for de- 

 positing different metals, and described the mode 

 forming them, we now offer a selection of those which 

 are in most general use in the trade. 



1st For depositing zinc, which is not very often at- 

 tempted, tho sulphate solution (105) may be used. 



2nd. For depositing copper upon all ordinary metals 

 except zinc, tin, lead, iron, and steel), and upon gutta- 

 percha, wax, and elastic moulds, after being mado 



