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On a Re-arrangement of the Molecules of a Body after Solidifi- 

 cation* By Robert Warington, Esq.* 



Having occasion lately to prepare some alloys of lead for the purpose 

 of lecture-illustration, 1 was much surprised at an alteration taking place 

 in the arrangement of the particles of one of these alloys, as shewn by 

 the appearance of the surfaces of fracture, after the metal had assumed 

 tlie solid form. The alloy experimented on was that known as Newton's 

 fusible metal, composed of 8 parts of bismuth, 6 of lead, and 3 of tin. On 

 pouring this alloy, in the melted state, on a marble slab, and breaking it 

 as soon as solid, and when it may be readily handled, the exposed sur- 

 faces were found to exhibit a bright, smooth, or conchoidal metallic ap- 

 pearance, of a tin white lustre ; and the act of disjunction at one part 

 will, frequently, cause the whole to fly into a number of fragments, ana- 

 logous to the breaking a piece of unannealed glass. 



The metal after this becomes so hot as to burn the fingers if taken up ; 

 and when this evolution of heat has ceased, the alloy will be found to 

 have entirely altered its characters, having lost its extreme brittleness, 

 requiring to be bent to and fro several times before it will break, and 

 presenting on fracture a fine granular or crystalline surface of a dark 

 colour and dull earthy aspect. Similar phenomena accompany the cast- 

 ing of the fusible alloy of V. Rose, composed of 2 parts of bismuth, 1 of 

 lead, and 1 of tin. 



The fact of the evolution of heat from the alloy of Newton, and its 

 cause, are thus noticed by Berzelius in his Traiti de Chimie : — " If this 

 alloy is jilunged into cold water, and quickly withdrawn and taken in 

 the hand, it becomes sufficiently hot, after a few moments, to burn the 

 fingers. The cause of this phenomenon is, that during the solidification 

 and crystallization of the internal parta, the latent heat of these is set 

 free, and communicates itself to the surface before the fixing and cool- 

 ing." The alteration in the internal arrangement of the particles, as 

 proved by the surfaces of fracture, is not however noticed, and the ex- 

 planation is defective, as it supposes the interior not to have assumed the 

 solid state until the evolution of the heat occurs. If such were the case, it 

 would be seen on breaking it in the first instance. The phenomena can 

 only be accounted for by admitting a certain degree of mobility among 

 the particles, and that a second molecular arrangement takes place after 

 the metal has solidified. This may arise from their not having assumed, 

 in the first state, that direction in which their cohesion was the strongest. 



That a verj- marked and extraordinary alteration in the characters and 



• Communicated by the Chemical Society ; having been read January 4. — Phil, 

 Mag, S. 3, vol. xx, No. 134 ; Suppl. July 1842. 



