It has long been known that fine gold or gold coin can be dissolved, if fastened to the negative pole of a galvanic battery and immersed in a strong solution of cyanide of potassium, but I believe that, previous to my discovering the fact, it has not been known that gold can be dissolved in cyanide of potassium without the use of any acids or of the battery, simply by procuring a lot of refuse gold from the bookbinder's or sign painter's (at SO cents per dwt.) and immersing it in a solution of cyanide of potassium, and in a short time it will disappear, having been dissolved in that menstrum. In like manner the gold contained in the rags used by the gilder, for removing superfluous gold leaf, may be reclaimed simply by soaking the rags in the solution for a short time, taking them out and pressing the liquid. The gold is taken up in the liquid without injuring the rag in the least. The result is a saving of time, trouble, and expense. To the truth of the two first, the electro plater will readily affirm, for he may by using the battery lately discovered (a strip of zinc pointed with copper and immersed in the cyanide gold solution), dispense entirely with nitro muriatic and sulphuric acids, either in their use of dissolving or depositing the gold. The gold-beater here does for us, by mechanical means, what we were heretofore under the necessity of doing with powerful chemical solvents, namely, distending the surface of the gold almost infinitely, thereby diminishing its attraction of cohesion so much that it is readily dissolved in this feeble solvent. Refuse gold leaf can be bought for 80 cents per dwt., whereas coin ol equal fineness is worth one dollar—leaving a saving of 20 per cent. Cyanide of potassium is also an excellent means of removing misplaced gilding irom books, signs, or picture frames. For this purpose, by means of a sponge, the gilding is kept moist for a short time with the liquid, when the gold will be found to be dissolved without injuring those articles in the least. J. F. MASCHER.
This article was originally published with the title "Interesting Discovery in Electro Gilding" in Scientific American 8, 36, 288 (May 1853)