OF METALS CONSIDEKED IN RELATION TO THE PERIODIC LA.W. 347 



both singly and in association, has been investigated. Questions of much industrial 

 interest present themselves, especially iu connection with iron; with regard to this 

 metal, the evidence as to the action of other elements upon it would appear to tend in 

 the same direction as in the case of gold, although the question is greatly complicated 

 by the relations of iron to oxygen, and by the presence of occluded gases. It may 

 be sufficient for the present to point out that the atomic volume of iron is 7 P 2 ; carbon, 

 the atomic volume of which is small (4'0), when present in quantities varying from 

 0'2 to 1 per cent, increases its tenacity. Silicon, notwithstanding that it has a larger 

 atomic volume (ll'l) than iron, apparently increases its tenacity, although little can 

 as yet be said as to its influence in very small quantities. The same observation 

 applies to small quantities of manganese. This metal has an atomic volume of 6*8, 

 and when present in very large quantities, 12 to 15 per cent., confers great extensi- 

 bility on iron. Sulphur and phosphorus, on the other hand, have large atomic volumes, 

 15'1 and 13'2 respectively, and both these elements have, as is well known, a preju- 

 dicial effect on the qualities of iron. 



It should not be forgotten that the knowledge of the effect produced on metals by 

 small quantities of added matter has had a remarkable effect on the development of 

 chemistry, mainly by sustaining the belief of the early chemists in the possibility of 

 "ennobling" base metals or "degrading" precious ones. This is specially evident 

 from the writings of GEBER, BIWNGUCCIO, GELLERT, and ROBERT BOYLE ; and it is 

 hardly strange that, in the absence of a knowledge of analysis, they should have 

 believed in the efficacy of a transmuting agent, when it is remembered that in the 

 specimens submitted to the Society the presence of yioth part of such metals as lead, 

 bismuth, and potassium has entirely altered the appearance of the fractured surfaces 

 of pure gold. 



ADDENDUM, 



August 1, 1888. . 



The test-pieces were all cast in the same mould, and their sectional area was about 

 0'06 of a square inch ; the sixth column of the Table, p. 344, gives the reduction per 

 cent, in sectional area of many of the test pieces at the point of fracture, so far as it 

 was possible to measure them, but the irregular nature of the fractured surface 

 rendered the measurements for the most part untrustworthy, and it would therefore 

 be of but little use to plot these data on a curve. The behaviour of several of the 

 test-pieces under longitudinal stress resembled that of a viscous solid, and in such 

 pieces the fracture was wedge-shaped, with a more or less sharp edge, the section 

 remaining rectangular. 



In some cases, notably in that of the test-pieces containing palladium and lithium, 

 tin- fractures revejilcd tin- presence <>f a minute cavity, which, doubtless, determined 



2 Y 2 



