Intelligence and Miscellaneous Articles. 77 



does in the circuit in a time t, is C 2 (R 1 + 'R 2 )t ; of which an amount 

 C 2 B^ is done inside the cell, and the balance C 2 B 2 £ outside. This 

 latter amount is necessarily equal to the product of the quantity of 

 electricity passing, Ct, into the difference of potential between the 

 ends of the external resistance, which latter quantity is E 2 ; that is, 



c 2 b 2 *=e 2 c*. 



Hence E 2 =CB 2 = -^_ E, ; 



or, E 2 is less than E x by an amount which is the greater the larger 

 is B x in reference to\ : if B X = B 2 , E a =iE t . In Mr. Shida's 

 experiments B x was 2-02 ohms, whilst B 2 was successively 80*86, 

 110*86, and 130*86 ohms, averaging 107*53 ohms. The mean 

 electrostatic value obtained by Mr. Shida was consequently nearly 

 2 per cent, too small ; so that the value of v finally deduced by divi- 

 ding the electromagnetic value by the electrostatic value must have 

 been just as much in excess of the truth. 



THE PHENOMENON CALLED THE 

 BY J. C. DOUGLAS. 



If a piece of tin be bent it emits a sound ; this, being regarded 

 as a property peculiar to tin, has been termed " the cry of tin." 

 This phenomenon is explained by the peculiar crystalline structure 

 of the metal. If the explanation be the true one, then other metals 

 which are obviously crystalline in structure should also exhibit the 

 phenomenon under favourable conditions. But it is exceedingly 

 difficult to place other metals in a crystalline 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. Rolled zinc is very 

 tough as compared with cast zinc ; and its fracture is not crystal- 

 line, 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 cannot 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 structure ; that rolling in the case of tin and zinc, 

 and probably in other cases, destroys the property with the altera- 

 tion 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 temperature on rolled 



