MECHAXKX .\XD USEFUL ARTS. Gl 



ON THE COMPARATIVE STRENGTH OF LEAD AND TIN PIPE. 



As the substitution of block tin pipe in place of lead, is rapidly taking 

 place, for the conveyance of water, the following results of experiments 

 instituted by Dr. W. H. Ellet, of New York, on the comparative strength 

 of the two metals, to resist hydraulic pressure, will prove interesting. Dr. 

 Ellet, in his report, says : For the purpose of determining the power of 

 tin to resist pressure, absolutely, as well as relatively, to that of lead, I 

 caused to be manufactured coils of pipe of the two metals, of precisely the 

 same dimensions. They were made, by hydraulic pressure, with the 

 same machine, the metals being urged through the same die, and passed 

 over the same mandril. The interior diameter of these pipes, was five- 

 eighths of an inch, the exterior seven-eighths, and their thickness was, of 

 course, one-eighth of an inch. The lead pipe was tried first. A pressure 

 of 50 Ibs. to the square inch, was applied, without any sensible effect. 

 The pressure was now gradually increased, and when it had risen to some- 

 where about 200 Ibs. to the inch, the pipe began to swell uniformly. Con- 

 tinuing to increase the pressure, the dilatation increased likewise, until 

 having reached a force of 397 Ibs. to the inch, a sort of aneurismal tumor 

 appeared at one point, where the metal rapidly thinned out, and at length 

 parted, with a longitudinal fissure, having sharp edges. The dilatation in 

 the rest of the pipe, had increased its diameter from seven-eighths of an 

 inch to one and one-eighth. 



The tin pipe was next put under trial. The initial pressure here was 

 that at which the lead pipe had given way, viz. : 397 Ibs. to the inch. On 

 increasing the pressure rapidly, dilatation was not observed until the force 

 employed was somewhere between 800 and 900 Ibs. to the inch. The pipe 

 burst at the pressure of 1,212 Ibs. to the inch, presenting, at the point of 

 rupture, piecisely the same appearance as the lead had done. The gener- 

 al dilatation had increased the diameter, from seven-eighths of an inch to 

 precisely one inch. These experiments show, most conclusively, that the 

 strength of tin pipe to resist internal pressure, is more than threefold that of 

 lead. 



The greatest pressure on the distributing pipes of the Croton, in the city 

 of New York, does not exceed SO Ibs. to the square inch. 



IMPROVEMENTS IN THE MANUFACTURE OF IROX. 



Mr. H. Leachman, of Islington, England, has patented an invention, 

 which consists in treating iron by means of certain materials, or a certain 

 combination of materials, for the purpose of producing more plastic and 

 malleable iron than heretofore. For this purpose, common brick- dust, 

 salt, black oxide of manganese, and pig-iron, are employed, as herein-after 

 mentioned. The first three mentioned materials are mixed together, in the 

 following proportions, that is to say : Common brick-dust, 120 Ibs.; com- 



