M. TECHNOLOGY. 513 



luted with water to 10.5 pints. Into this solution (which 

 contains about 385 grains of nickel to the pint), when cold, 

 1543 grains of carbonate of ammonia are introduced, 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 deposit of nickel. 

 The temperature of the bath during use must be retained at 

 about 122. Addition of caustic potash or soda renders 

 heavier deposits possible. 15 C, 1 873, xxiv., 384. 



RESTORING BURNED STEEL. 



Mr. J. L. Davis announces to the London Iron what he 

 calls a simple and efficacious plan of restoring to steel which 

 has once been burned its usual valuable qualities, claiming 

 that this can be accomplished by the use of a fluid which 

 leaves scarcely any thing to be desired on the score of cheap- 

 ness. The process consists in the use of a resin oil, with 

 which is intimately mixed about one fourth of its weight of 

 the residue of paraffin e stills. Chisels that have become use- 

 less may thus be restored and made as valuable as ever. The 

 burned steel must be heated red-hot, then plunged into the 

 liquid for a few seconds, then reheated and cooled in the or- 

 dinary way, when the steel is said to be perfectly restored. 

 3 A, May 30, 1873, 677. 



VERY ADHESIVE MUCILAGE, OR VEGETABLE GLUE. 



The addition of a solution of 30 grains of crystallized sul- 

 phate of alumina, in 300 grains of water, to a solution of 1050 

 grains of gum arable, in 2625 grains of water, affords a muci- 

 lage that will fasten lightly sized paper, printing-paper, etc., 

 or wood to wood, paper to metal, etc. 13 C, July 1, 1874, 

 858. 



TEMPERING STEEL. 



It is not generally known that steel can be made so hard 

 that it will pierce any substance but a diamond. Many jew- 

 elers and lapidaries experience great difficulty in getting the 

 points of their drills hard enough to pierce an amethyst. For 

 their benefit, as well as for that of miners and others using 

 drills requiring a very hard point, the following method of 

 treatment is recommended : The drills should be held, if 



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