1881.] Library. 43 



explanation be the true one, then other metals which are obviously crystal- 

 line in structure should also exhibit the phenomenon under favourable 

 conditions, but it is exceedingly difficult to place other metals in a crystal- 

 line state under proper conditions, e. g., cast iron and cast zinc in thin rods 

 break before they can be bent sufficiently to emit audible sounds, while 

 rolled zinc has had its crystalline structure destroyed by rolling and so is 

 not in a condition to emit sound when bent. Boiled zinc is very tough 

 as compared with cast zinc, and its fracture is not crystalline, but of an 

 even fine-grained bluish tint destitute of the brilliant lustre presented by 

 this metal in a crystalline state. If, however, a piece of rolled zinc be 

 heated for a few minutes to a temperature somewhat below its melting 

 point, the metal becomes much less tough, and its fracture is decidedly 

 crystalline. On bending a piece of zinc so treated it emits a sound weaker 

 than, but of the same nature as, the sound emitted by tin. Cast zinc can- 

 not be bent readily, but if it be pinched between the teeth or with pliers it 

 emits the sound distinctly. 



It appears therefore that the cry of tin is due to crystalline structure, 

 that it is not characteristic of tin as generally accepted, but may be emitted 

 by zinc and probably by other metals when crystalline in texture ; that 

 rolling in the case of tin and zinc and probably in other cases, destroys the 

 property with the alteration of texture ; that in the case of zinc which has been 

 rolled, the crystalline texture may be produced without melting the metal 

 but by merely heating it, and this is so readily done that it affords a ready 

 illustration of the effects of high temperatures on rolled metal. If as sup- 

 posed this sound is characteristic of the crystalline structure of metals, it 

 may afford a means of great practical use whereby by the sound a metal emits 

 we may draw conclusions as to its texture and hence its fitness for certain pur- 

 poses, or by the sound emitted by a beam when bent we may draw conclusions 

 as to its safety, the microphone or other appliance being called in to aid us 

 where the sounds are exceedingly weak. 



