M. TECHNOLOGY. 539 



perature the yield was considerable ; and gold bronze, after 

 repeated purification with hot nitric acid and with caustic 

 soda, appears by sunlight as a beautiful gold-yellow uniform 

 powder; by higher temperature it acquires a cast of red. 

 The violet bronze (the potash compound) needs a higher 

 temperature. 14 C\ CCXL, 484. 



NEW PROCESS FOR NICKEL PLATING. 



Martin and Delamotte use organic acids with the salts of 

 nickel instead of the mineral acids usually employed. The 

 bath is prepared by dissolving 3858 grains of citric acid, 

 1543 grains of sal ammoniac or sulphate of ammonia, and 

 1543 grains of nitrate of ammonia in 6.3 pints of water, 

 heating the solution to 176, gradually saturating it with 

 freshly precipitated hydrated oxide of nickel, and then al- 

 lowing it to cool. One pint of ammonia is next added, and 

 the whole diluted with water to 10.5 pints. Into this solu- 

 tion (which contains about 385 grains of nickel to the pint), 

 when cold, 1543 grains of carbonate of ammonia are intro- 

 duced, and the liquid filtered after settling. The liquid is 

 deep blue, and of about 11 Baume, and, under the influence 

 of the current, readily affords a compact, brilliant, white de- 

 posit of nickel. The temperature of the bath during use 

 must be retained at about 122. Addition of caustic pot- 

 ash or soda renders heavier deposits possible. 15 C\ 1873, 

 xxiv., 384. 



TINNING LINEN AND COTTON FABRICS. 



Linen and cotton goods, according to Jacobson, may be 

 tinned by first applying to their surfaces commercial zinc 

 dust, rubbed to a thin mass with weak albumen, by means 

 of a brush or roller. When dry, the albumen is coagulated 

 by steam, and the goods are immersed in a solution of tin 

 chloride. The tin is deposited in a finely divided state upon 

 the zinc, and is then to be burnished. Linen prepared in 

 this way is said to be a good water-proof substitute for tin- 

 foil in many cases. 21 A, July, 1874. 



BRONZING WOOD. 



Saturate the article first with hot parchment glue, previ- 

 ously filtered and not too weak, and, when dry, coat while 



