ON THE MECHANICAL PROPERTIES OF METALS. 



107 



The slight deteriorations and loss of strength from the first up to the 

 eighth melting, and the progressive and striking increase which took place 

 from the eighth up to the maximum* or the twelfth melting, indicate some 

 curious and interesting pheenomena in the fusion of cast iron. It will be 

 observed that after the first melting, there is a steady and progressive de- 

 crease of strength till the fourth melting, when it again begins to rise and 

 keeps steadily on the ascent till the thirteenth melting, when it again begins 

 to decrease, at first progressively up to the fifteenth, when it suddenly falls 

 from 603 to 371, and from this again downwards to the last or eighteenth 

 melting, when it falls as low as 312; and at which time the iron becomes 

 perfectly useless, from its flinty hardness and its obdurate nature in resisting 

 the attacks of the hardest steel. 



The general summary will, however, exhibit the peculiar properties of the 

 irons produced from each melting. Some of them, but more particularly 

 those towards the close of the experiments, presented appearances in their 

 sectional fractures of an extremely curious character. These I have en- 

 deavoured to describe at the bottom of each table ; and I now refer to the 

 following summary, where the results of each experiment will be found ta- 

 bulated in the order in which they were made. 



General Summary of Results. 



