334 PROCEEDINGS OF THE AMERICAN ACADEMY. 



both in its natural state and quenched from a red heat, and with cast 

 iron. 5 The same efifect is shown by the same grades of steel when 

 broken off by twisting under a mercury surface, showing that the 

 amalgamation does not depend on the nature of the rupturing stress. 

 This effect was shown in a striking way by one of the hardened tool 

 steel cylinders. (See Plate.) This cylinder broke on the first applica- 

 tion of pressure at 1500 atmos. Examination showed a small harden- 

 ing crack at A from which the crack spread into the sound metal. The 

 mercury, escaping under pressure through the freshly opened crack, 

 produced nearly complete amalgamation of the entire section of the 

 cylinder, as the photograph shows. 



But on the other hand, all attempts failed to amalgamate the freshly 

 broken surface if it had once come in contact with the air. A test 

 piece like the above was supported directly over a mercury surface so 

 that the fragments fell immediately into the mercury when rupture 

 occurred. No trace of amalgamation was obtained here, as was also 

 no trace with several modified forms of the experiment in which im- 

 mersion was not so immediate. 



Experiments were now made to find whether the amalgamation so 

 produced might be made to work its way through the mass of the 

 metal. Fragments of the above amalgamated test pieces were sealed 

 into a bulb containing mercury so designed that the pieces should be 

 kept below the surface of the mercury. The air was boiled out, the 

 bulb sealed, and the whole kept at a temperature of 180° C. for three 

 hours in an oil bath. The pieces were then examined for amalgama- 

 tion by breaking them across. The hardened nickel steel piece 

 showed amalgamation throughout its entire mass, the bessemer showed 

 isolated splotches of amalgamation, while none of the others showed any 

 effect. Similar amalgamated bits from the broken test pieces were 

 now submerged in mercury, which was subjected to a pressure of 6500 

 atmos. at room temperature for six hours. All of the specimens, ex- 

 cept the soft tool steel, now showed amalgamation throughout the 

 interior. The hardened nickel steel piece was amalgamated completely, 

 while the amalgamation of the others was not so perfect, being con- 

 fined to patches near the surface. 



Further, pressure by itself is not capable of producing amalgamation 



" Aluminum may also be amalgamated by rupturinp; under the surface of 

 mercury. AUuninum so treated, when exposed to the air, shows the char- 

 acteristic tree-like growth of the oxide. The same effect is also shown in 

 nickel and cobalt. It should be remarked that the amalgamated iron surface 

 shows no tendency to oxidize in the air, but keeps its silver luster untarnished 

 at least for months. 



