M. TECHNOLOGY. 537 



the stopper should be held firmly against a flat surface of 

 common cork until the rubber is completely perforated. 1 

 A, August 20,1872,104.. 



UTILIZATION OF SCRAPS OF TINNED IRON. 



The method of utilizing scraps of tinned iron, devised by 

 Dr. Adolph Ott, is said to answer an excellent purpose, and 

 to be in successful operation in various German tin-plate es- 

 tablishments in ISTew York. For the purpose in question the 

 scraps are j^laced in large perforated copper vessels, and ro- 

 tated from thirty to forty minutes in a tank containing warm 

 hydrochloric acid, when the tin, lead, and about five per cent, 

 of iron will be dissolved. The copper drum is then lifted 

 from the acid into a vessel of water, then into one of alkali, 

 and again into water, when the scrap will be found free from 

 tin, and may be sent to the puddling furnace. 



The lead may be separated from the solution by the addi- 

 tion of sulphuric acid, and the tin may be obtained in the 

 metallic state by immersing plates of zinc in the liquid. Thus 

 regained, it requires only washing in water to be ready for 

 melting and casting into blocks. 



The solution left behind after the separation of the tin, 

 containing chiefly chloride of zinc and iron, is said to be 

 serviceable in preserving timber by impregnation. 1 D, 

 August, 1872, 82. 



IMPROVED MODE OF NICKEL PLATING. 



Mr. Keith announces an improved method of nickel plat- 

 ing, by which he obtains a flexible and tenacious deposit, the 

 ordinary coatings of this metal being so brittle that the arti- 

 cles will not admit of the least bending. The invention con- 

 sists in adding to the various solutions of nickel, whether 

 formed of single or double salts, materials which, by their 

 presence, prevent the decomposition of the solution of the 

 plating bath, and the deposition of oxide of nickel and other 

 impurities upon the articles receiving the coating of nickel. 

 There is added to the solution of nickel one or more salts, ei- 

 ther single or double, acid or neutral, or associate, formed by 

 the union of organic acids, acetic, citric, and tartaric, with the 

 alkalies and alkaline earths, ammonia, soda, potash, magnesia, 

 or alumina. These additions will, it is asserted, counteract 



Z2 



