8 Mr. Daniell on the Action of Mercury , 



experiment : at the end of three days, during which it was 

 frequently turned, the terminal edges were cleft all round, and 

 irregular cracks appeared upon various parts of its surface. 

 Two solid pieces, approaching the hemispherical form, but 

 much flatter, were extracted from the ends by the point of a 

 knife, and two cup-like cavities were formed in the bar. By 

 introducing the edge of the knife into the cracks upon the sur- 

 face, its substance was broken away in parts, and a concentric 

 arrangement of the amalgam disclosed round a central nucleus 5 

 the appearance of which is represented at Fig. . The out- 

 side coating, 6, 6, was perfectly brittle, but the centre 

 rod, a, a, still partially retained its malleability, and could 

 be bent two or three times backwards and forwards, before it 

 broke. 



EXPERIMENT XI. 



Another bar of tin was cast, of the form and dimensions of 

 half the preceding cylinder, divided longitudinally. Its ap- 

 pearance, after being treated with mercury as described, is 

 exhibited at Fig. 3. Its two lateral edges were sharply cleft 

 asunder, as at a, a, and some irregular cracks appeared upon 

 its round surface. Part of the substance of the amalgam was 

 broken away, as shewn at b t when a centre cylindrical rod 

 appeared, and the concentric arrangement was apparent, as in 

 the last experiment. 



EXPERIMENT XII. 



Having cast a cylinder of tin, similar to that employed in 

 Exp. x., one half of it was made square by the file, and the 

 whole was then submitted to the action of mercury as before. 

 The cleavage down the lateral edges, which were very sharp, 

 was perfect, and a most beautiful pyramid was formed at the 

 square end. The cylindrical portion of the bar was irregularly 

 cracked, and there seemed to be a tendency of the clefts in the 

 square edges to continue their course into this part. These 

 results are represented at Fig. 4; a is the terminal pyramid, 

 by b the cleft upon one of the edges of the square bar ; c, c the 

 cylinder. 



