Constants of Solid Bodies. 269 



found for a and b does not, with individual exceptions, exceed a 

 few per cent., which may be considered surprising when the 

 possible sources of error are taken into account, and we remember 

 the difficulty of obtaining constant results for similar determi- 

 nations in the case of liquids. 



As the formula holds for annealed wires, the author does not 

 think with Karmarsch that the metal is first condensed on the 

 surface by the pressure in the draw-plate and its texture advan- 

 tageously altered. It does not follow thence that the increase in 

 the density of the metal necessitates an increase of those con- 

 stants a and b. On the contrary^ the theory says that this in- 

 crease must be greater for b than for a, in accordance with ex- 

 periment. 



Karmarsch gives the thickness of wires in millimetres, the 

 tenacity in pounds. Taking /as the tenacity in grammes for 

 wires of the diameter r in millimetres, or 



/=*27rr + £77T 2 , 

 we have 



«=-500, /3 = «-500; .... (2) 



7T IT 



and the values of the constants a. and ft are then easily deduced 

 from the values of a and b given by Karmarsch. The following 

 Table gives some values of a, where a is the constant of capil- 

 larity of solid metals at ordinary temperature (15°), and mea- 

 sures the pull exerted upon 1 millim. of surface. The numbers 

 may be readily compared with the ordinary capillarity-constants 

 of liquids, which are usually given in milligrammes. (Vide Fort- 

 schritte der Physik, 1863, vol. xix. pp. 68-74.) 



Capillarity-constants of solid Metals. 



Hard-drawn. Annealed, 



gr. gr. 



Iron 5731 1592 



Platinum . . . 3025 2388 



Copper .... 2388 



Silver .... 2388 478 



Gold 1592 478 



Zinc 557 



Steel 6685 955 



Argentan . . . 6685 1114 



Silver .... 5253 2547 



Gold (14 carats) . 3661 2228 



Brass (wire) . . 2547 1751 



Brass (string) . . 1751 637 



The values thus found are very great if compared with the 



