88 REPORT — 1853. 



meltings, ne constant reproduction of tlie same metal was carefully preserved, 

 and that under the same circumstances of fusion, as respects coke and flux, 

 as those previously melted, until the whole of the metal was exhausted. 



In these consecutive meltings, it will be observed that the same quantity 

 of coke and limestone was used, but at each separate process the quantity of 

 iron was diminished until the waste and the abstraction of a few specimen 

 bars — reserved each time for the succeeding experiments — had exhausted 

 the quantity with which the furnace was originally charged. These pre- 

 cautions became the more essential, as any admixture, or any change in the 

 furnace might alter the conditions under which the castings were produced, 

 and thus render them to some extent abnormal for those researches and 

 points of comparison which, under all the circumstances, it was necessary to 

 observe. To avoid these discrepancies, the furnace was retained of uniform 

 dimensions, of nearly the same temperature, and having the coke and lime- 

 stone carefully weighed at every charge; the castings were, by these means, 

 obtained from a uniform system of treatment maintained from the beginning 

 to the end of the process. 



The bars derived from each successive melting were placed upon two iron 

 brackets, a, a, exactly 4 feet 6 inches apart, screwed to the sides of a 

 wooden frame of the form and dimensions shown in the annexed figure. 



On the centre of the cross bar A the socket b was fixed, and through this 

 socket the rod c, screwed on the top end, was passed. This rod had a slit at 

 the bottom to admit the bar ; and the wheel D having a nut in its centre and 

 fitting the screw, the scale with the weights B could be raised or lowered 

 upon the middle of the bar according as the weights were successively laid 

 on to measure the deflection, or taken off to ascertain the defects of elasticity 

 or permanent set. 



The pig iron used in these experiments, and from which the following 

 results were obtained, was No. 3 Eglinton Hot-blast. From its blue tinge 

 and large crystalline structure, it had the characteristics of No. 1 more than 

 No. 3 ; and judging from its appearance, it indicated a ductile and superior 

 quality of iron ; probably of more value for its working properties than its 

 powers of resistance to strain. This .property in the metal was not how- 

 ever objectionable, as it enabled us to continue the experiments through a 

 longer series of meltings before it arrived at the point of maximum strength, 

 and those chemical changes which affected the formation of its crystalline 

 structure. Under the circumstances, and considering the objects to be at- 

 tained in the research, it was probably as good a selection as could have been 

 made for such an inquiry. 



For the purpose of ascertaining progressively the effiect of the load upon 

 the bars, it was considered expedient to lay on weights not exceeding 56 lbs. 

 at a time, and by careful attention to the gauge and the scale made in the form 

 of a wedge, and divided into the tenths and hundredth parts of an inch, the 

 deflection produced upon the bar was ascertained with the utmost accuracy. 

 Reading off the deflections was accomplished with great care; and in order 

 to indicate the amount of permanent set produced by the different weights 

 as they were laid on, the scale was screwed up at every second or third in- 

 crease of the load, and applying the scale to the gauge, the defects of elasti- 

 city were easily determined, and recorded in the Tables in the usual way. 

 Having thus selected the metal and prepared the apparatus, the experiments 

 were proceeded with as exhibited in the following Tables. 



