510 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



drained or evaporated to dryness, or used when of a pasty 

 consistency. This oxide is then put into an earthenware pan, 

 and as much sulphuric or muriatic acid, or sulphuric and nitric 

 acid, is added as will take up the oxide and hold the tin in 

 solution. A mixture of two parts of muriatic acid to one 

 part of sulphuric acid seems to give the best result. This 

 solution of tin is put into the vat in which the articles to be 

 coated or plated are immersed, and as much soft water added 

 as will make a bath of the strength ordinarily used in electro- 

 plating. This is now ready for use. 



In addition to the use of this process for coating new me- 

 tallic objects, it has lately been extensively employed in ren- 

 ovating worn and tarnished articles, experiments upon some 

 that have been completely eaten into by rust showing that 

 they can be so coated as to have the appearance of frosted 

 silver. To accomplish this result, if the articles are of iron 

 and very rusty, they are first placed in a bath of diluted sul- 

 phuric acid, after which they are immersed in a bath of pot- 

 ash and water made hot, which removes all the grease. They 

 are then removed to the plating vats, which are of novel con- 

 struction. At the end of the vat is a plate of metal in con- 

 nection with one ot the poles of a galvanic battery, while 

 over it are metal bars in connection with an opposite pole. 

 The articles intended for plating are then hung in the solu- 

 tion from the bars by means of copper wire, when galvanic 

 action takes place, and they remain more or less time, accord- 

 ing to thickness of the plating required. When withdrawn 

 from the vat, the articles are of a dull, whitish color, and 

 need to be subjected to the action of a metallic brush, moist- 

 ened with a cleansing solution, if the dull appearance be not 

 desirable. The articles thus treated have the appearance of 

 silver, with almost the cheapness of tin. 3 A, April 25, 1874, 

 523. 



MALLEABLE BRASS. 



An alloy may be prepared as follows, which resembles red 

 brass in color, and which may be hammered into any shape 

 when first prepared, while warm, without splitting or crack- 

 ing, but which when rapidly cooled, and again heated to red- 

 ness, is brittle under the hammer, but recovers its malleability 

 it gradually cooled. First fuse 33 parts of copper in a loosely 



