MECHANICS AND USEFUL ARTS. 97 



or retort heated at from 212 to 302 F., and, when thoroughly dry, it is 

 removed to another furnace, where it is brought to a cherry-red heat ; 

 the adhering vitreous matter now fuses, and when the fusion is com- 

 plete and the glass seems to have flowed over the whole surface, the 

 article is removed from the furnace and placed in a close chamber, 

 from which the air is entirely excluded, where it is kept till it has 

 cooled dow r n to the temperature of the atmosphere. The vitreous 

 compound used consists of the following substances: Powdered 

 flint-glass, 130 parts ; carbonate of soda, 203 parts ; boracic acid, 12 

 parts. These must be melted together in a " glass pot," and a fusi- 

 ble glass will be the result; when cold, this must be pounded with 

 care, so as to be reduced to a powder fine enough to pass through a 

 silk sieve. If the first coating is found to be imperfect, a second one 

 may be applied ; but in all cases the vitreous matter and the metal 

 must be quite free from all foreign matter. Civil Engineer and Ar- 

 chitect's Journal, Feb. 



COATING FOR CAST-IRON. 



MR. W. WYATT has patented a glaze, consisting of three parts, by 

 weight, of white-lead (or one part of red-lead and two parts of white- 

 lead) to two parts of borax and one part of calcined flint, which are to 

 be fused, run into water, and ground in a glaze-mill to the consistency 

 of cream. The article coated is to be placed in a kiln in such away 

 that no flame or sulphur shall touch it, and heated till the glaze melts. 

 London Builder, May. 



COATING IRON WITH COPPER. 



MR. E. G. POMEROT, of St. Louis, has patented a process for coat- 

 ing iron with copper. All impurities are first removed by an acid, 

 after which the iron is dipped into clay moist enough to leave a thin 

 coating upon it. It is then dried over a brisk fire, and immersed in 

 molten copper, when enough of the latter adheres to it to cover it 

 completely. It may afterwards be smoothed and polished by rollers. 

 Hammering does not separate the copper from the iron. Farmer 

 and Mechanic, Sept. 19. 



TENACITY OF METALS. 



As the results of numerous experiments, M. Baudrimont has ar- 

 rived at the following conclusions : 1. The tenacity of metals varies 

 with their temperature. 2. It generally decreases, though not with- 

 out exception, as the temperature rises. 3. With silver, the tenacity 

 diminishes more rapidly than the temperature. 4. With copper, 

 gold, platinum, and palladium, it decreases less rapidly than the tem- 

 perature. 5. Iron presents a very peculiar and remarkable case ; at 

 212 F. its tenacity is less than at 32, but at 392 it is greater than 

 at 32. Comptcs Rcndus, July 29. 



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