1888.] 



Properties of Metals and the Periodic Law. 



427 



quantity, bat, unfortunately, slight variations in high melting points 

 are very difficult to determine with even approximate accuracy, 

 and it appeared to be better to ascertain the effect of metallic and 

 other impurities on the cohesion of the gold, as indicated by the 

 amount of force externally applied in an ordinary testing-machine, 

 and in that way to ascertain whether the effect of added metals is 

 amenable to any known law. 



The purest gold attainable has a tenacity of 7'0 tons per square 

 inch, and an elongation of 30*8 per cent, on 3 inches. Professor 

 Kennedy found that a less pure sample which contained 999*87 parts 

 of gold in 1000, broke with a load of 6'29 tons per square inch ; it 

 had an elastic limit of 2*12 tons per square inch, and elongated 18" 5 

 per cent, before breaking. In the following experiments only the 

 purest gold that could be prepared was employed. The effect on the 

 tenacity of gold produced by adding to it about 0*2 per cent, of 

 various metals and metalloids is shown in the following table, in 

 which the results are arranged according to the tensile strengths : — 



Name of element 

 added. 



Tensile 

 strength. 



Elongation, 

 per cent, (on 

 3 inches) . 



Impurity 

 per cent. 



Ato adc 

 volume 

 of im- 

 purity. 





Tons per sq. in. 











Less than 0" 5. 



Not perceptible. 



Less than '2 



45-1 





0-5 (about) 



0-210 



20-9 





3-88 





0-186 



2 J- 5 





4-17 



4-9 



'240 



18-0 



Thallium 



6 21 



8*6 



0-193 



17-2 



Tin 



6 21 



123 



196 



16-2 





6 -0 (about) 



qy- 



0-203 



17 9 





6*88 



44-0 



0-202 



12-9 





7-10 



33 3 



0-200 



10-1 





7-10 



32-6 



0-205 



9-4 





7-54 



28 -4 



0-205 



9*1 





7-76 



25-0 



0-21 (about) 



8-4 



Manganese 



7-99 



29-7 



0-207 



6-8 





7-99 



26-5 



0-290 



15-3 





8-22 



43 5 



193 



7-0 





8-87 



21 



0-201 



11-8 





8'87 



25 5 



0-186 



10-1 



Reasons are given for adding the comparatively large amounts of 

 impurity (two-tenths per cent.), notwithstanding that even " traces " 

 of certain metals would have produced very marked effects upon gold, 

 and evidence is adduced to show that exact concordance in the 

 respective amounts of matter added to the gold is not of much im- 

 portance. 



