MECHANICS AND USEFUL ARTS. 77 



taken out, and, without being washed, dried, or undergoing any other treat- 

 ment whatever, are passed immediately, though slowly, into the bath of 

 melted alloy that forms the coating. Mr. Poleux employs muriatic, nitric, 

 or sulphuric acid, of the ordinary degrees of concentration in commerce, 

 (namely, muriatic, of 18 Beaumc ; nitric, 38 Beaume; and sulphuric, 66 

 Beaume, or thereabouts), without dilution. Scientific American. 



PRESERVATIVE PREPARATION FOR COATING METALS. 



A preparation for coating metals, highly spoken of in the English Mechan- 

 ical journals, consists of a composition formed by mixing gutta-percha with 

 common resin, tar, pitch, or asphaltum, and dissolving them in impure ben- 

 zine, or coal naphtha, or other volatile hydro-carbons obtained from bitumin- 

 ous shales or schists. The method pursued in preparing is to dissolve two 

 pounds of gutta-percha and four pounds of common resin, or tar, or pitch, 

 and one ounce of gum shellac, in four gallons of coal naphtha, these ingredi- 

 ents being placed in a suitable vessel and heated to about one hundred and 

 sixty degrees Fahrenheit, until the solids are completely dissolved. "When 

 the composition is applied as a paint, coloring matter is added to give the 

 required tint. 



IMPROVED ELASTIC TUBES FOR COUPLINGS. 



A method of making elastic tubes suitable for effecting the junctions of 

 pipes exposed to variable temperatures, or of pipes which are otherwise 

 strained or required to bend, as the tube-couplings connecting locomotives 

 with their tenders, hose for fire-engines, etc., has been patented by Mr. 

 James Webster, of Birmingham, England. The improved tubes are com- 

 posed of brass, copper, or other metal or alloy, and in them a series of cor- 

 rugations are made in planes perpendicular to the axis of the tube, to give 

 elasticity to the tube, and permit of its flexure within certain limits. "Web- 

 ster prefers to make the corrugations as deep as is compatible with the 

 nature of the metal or alloy of which the tube is made, and so narrow that 

 the shoulders between the corrugations shall touch each other on slight 

 flexure of the tubes. Tubes made according to this invention are elastic, 

 both longitudinally and transversely; that is to say, they are capable of 

 elongation and flexure, within certain limits, without taking a set. 



IMPROVEMENT IX THE MANUFACTURE OF MALLEABLE IRON. 



Mr. S. Fisher, of Birmingham, England, has patented some improve- 

 ments in the manufacture of anchors, shafting for mill and engine purposes, 

 axles, cranks, and spindles ; and in the furnaces, or muffles, used in those 

 operations. The improvements consist in casting the articles named in mal- 

 leable iron, and afterwards annealing them in a peculiar kind of muffle. 

 This muffle is built in the requisite shape to suit the article to be annealed, 

 of fire-bricks moulded to a suitable form instead of using an iron muffle, 

 which rapidly burns through. As the fire-brick muffle will last for numer- 

 ous annealings, the new process will be productive of great economy in the 

 cost of the operations to which it may be applied. 



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