therein. If a thin coating be desired, the patentees prefer using the solution boiling, when from a few seconds to a minute will produce the required effect; but if a thicker coating be desired, for the better description of goods, as plated ware, then the preferred mode is to use the solution cold, and apply a current of electricity to the articles to be coated ;-this may be effected by any of the ordinary means; but the patentees prefer using those batteries known as sustaining batteries. Should the articles be submitted to this latter process, the metal deposited upon them will assume a chrystalline appearance; if, therefore, a bright surface should be required, they must be finished with a wife brush, as is well understood; but if a deadened surface be desired, it may be obtained by annealing and boiling in dilute sulphuric acid, according to the usual method.

The patentees state, that it will be found necessary to add, from time to time, a fresh supply of the oxide to the solution, in order that it may be kept saturated with that salt.

When using the battery, the chloride, cyanide, or other salts, insoluble in water, may be used; and the patentees have sometimes employed a solution of the iodide in hydriodate of potash or soda, and occasionally the nitrate, oxide, or chloride of silver, in pure ammonia; but these are not so available. Other solutions may also be used, such, generally, as the ammoniacal solutions, or solutions of the chloride in the muriates of potash or soda; but these are found to be difficult of treatment.

Another mode of applying the battery is, first, to coat the article with silver, by the process first above described, or by other means; and, this being done, a further deposit may be effected by using a simple solution of silver, constituting a neutral salt; but this is not preferred.

The above modes are described as applicable only to

copper and its alloys; but, should it be required to silver surfaces of iron, it may be done by first cleaning the metal as hereafter described. Zinc and tin may also be coated as above.

The patentees claim, under this head of their invention, firstly, coating metals with silver by the use of oxide of silver, dissolved in prussiate of potash or other analogous salt, or in pure ammonia; secondly, the use of a solution of silver in prussiate of potash or other analogous salt, or in pure ammonia in combination with a galvanic current ; and thirdly, the use of a solution of silver in acid, so as to constitute a neutral salt in connection with a galvanic current; the articles in this case having been previously coated with silver.

The third head of the invention is as follows:-Two ounces of fine gold, converted into oxide, are to be dissolved in a solution of two pounds of prussiate of potash or soda in one gallon of water, and the whole boiled half an hour, when the solution will be ready for use. The articles to be gilt are immersed in the solution while boiling, and if a thin coating only be desired, the operation will be complete in from a few seconds to a minute; but if it be required to obtain a thicker deposit, the solution should be used cold, and in connection with a current of electricity, taking care to keep it saturated with the salt.

The patentees sometimes employ a solution of protoxide of gold (purple of cassius) in the muriates of potash, soda, or other soluble muriates; but this they do not find so desirable in practice, generally preferring those salts combining with gold in a low state of oxydation, and forming compound salts, having double bases, and which are found principally in that class termed "haloid salts;" those also capable of dissolving gold in a metallic state, as prussiate of potash, are applicable, but with different degrees of

efficacy. The best of all the above solutions the patentees consider to be that of oxide of gold in prussiate of potash.

Should it be desired to gild surfaces of iron with the assistance of the battery, a similar plan may be adopted to that described with reference to silvering by first slightly gilding the articles by any convenient method, and subsequently introducing it into one of the above solutions, and in connection with the voltaic battery.

The patentees claim, under this head of their invention, the use of a solution, for the purpose of gilding, formed of oxide of gold, dissolved in prussiate of potash, or soda, or any other analogous salt, and combining the action of a galvanic current with the use of a salt of gold as above, preferring the solution of gold formed by dissolving oxide of gold in prussiate of potash; and, further, the patentees claim, with reference to the two last heads of their invention, the application of a galvanic current, in combination with solutions of gold or silver for coating or plating with gold or silver, whether the articles to be so coated are formed entirely of metal, or only partly so.

The last head, viz.,that of preparing surfaces of iron to receive a coating of copper or other metal, consists in causing such iron surfaces to assume an electro-negative state while under the action of the acid, which is the cleaning medium. To effect this, the articles are to be connected to a piece of zinc, and placed in a solution composed of one part of sulphuric acid to one of water; after a short time the scales and dirt will fall from the iron, leaving its surface perfectly clean and bright; after which, if it be intended to coat the articles with copper, they are placed in a brass vessel containing a saturated solution of sulphate copper, with the addition of a little sulphuric acid; when, after keeping them there a short time, they will have obtained a firm coating of copper, and may be treated, if desired, as described with reference to the second and third head of these improvements.

The claim under this portion of the invention, is the method of coating iron with other metals, by the employment of the above mode of cleaning, as preparatory.—[Inrolled in the Inrolment Office, September, 1840.]

To THOMAS SPENCER, of Liverpool, carver and gilder, and JOHN WILSON, of the same place, lecturer on chemistry, for certain improvements in the process of engraving on metals by means of voltaic electricity.— [Sealed 7th October, 1840.]

In order to engrave on copper by the process of the patentees, the surface thereof is to be coated with etching ground or other protecting substance, the design traced thereon, and subsequently removed with an etching point, as is now ordinarily practised by engravers; after which it is to be immersed in a solution of sulphate of copper, and connected to the negative pole of a voltaic battery, another plate of copper being placed opposite to it, and in connection with the positive pole of the battery; the effect will be the biting away or corroding of those parts of the metal which have been left unprotected by the removal of wax with the etching point; the width and depth of the lines depending upon the distance between the two plates, the quantity or intensity of the battery, or the length of time devoted to the operation.

When the surface required to be engraved is of a cylindrical form, the plate connected to the positive pole of the battery should also be of that figure, and placed so as to surround the metal to be engraved, equidistant at all parts of its circumference.

If engraving on surfaces of iron or steel, the patentees

use, instead of the sulphate of copper, a solution of common salt, and connect the positive pole of the battery to another plate of iron or steel. When the metal to be operated upon is of silver, a solution of sulphate of soda or sulphate of silver is preferred, and a silver surface connected to the positive pole; or if it be required to engrave on gold, the solution into which it is placed is hydrochloric acid, gold forming the connection with the positive pole.

In like manner the patentees state other metals (metallic surfaces) may be engraved; they, therefore, do not confine themselves to those particularly mentioned, or to the form of apparatus described, but they claim the use or application of voltaic electricity for engraving on metals generally. —[Inrolled in the Petty Bag Office, April, 1841.]

TO JOSEPH LOCKETT, of Manchester, in the county of Lancaster, engineer, for certain improvements in manufacturing, preparing, and engraving cylinders, rollers, and other surfaces, for printing or embossing calicos or other fabrics.―[Sealed 27th August, 1840.]

THESE improvements in manufacturing, preparing, and engraving cylinders, rollers, or other surfaces, for printing or embossing calicos or other fabrics, consist, firstly, in the application of the power of galvanic or voltaic electricity; and by this means re-coating, covering, or thickening those cylinders, rollers, or other surfaces, which have been manufactured by this or any other process; the engraving or etching upon which is required to be obliterated, or which may have been reduced by former use, or to manufacture a new roller or cylinder by the same process.

To form a roller or cylinder by this process, a mould or

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