270 Mr. G. T. Beilby on the Hard 
very far short of that of the completely transformed amorphous 
iron, if we were only able to produce it. : 
52. From quite different considerations from the foregoing 
many metallurgists are disposed to associate the hardening of 
iron under thermal treatment with the existence cf an allo- 
tropic form of the metal itself, From observations made in 
another connexion, I am disposed to think there are grounds 
for believing that metals may be transtormed into and retained 
in the amor phous phase at temperatures above the transition- 
point by the mechanical action of gases. The suggestion 
here is that gas molecules passing in and out among the metal 
molecules may retain the metal in the mobile condition of 
phase M, and thus effectually prevent its crystalline rearrange- 
ment in the C phase, (See also paragraph 71.) Itis evident 
that if this gaseous disturbance were to continue till the metal 
had cooled to the transition-point, the opportunity for ery- 
stalline aggregation would be lost, and the amorphous condition 
would be ster eotyped i in the solid metal, 
53. Kendal has found that nickel may be kept at a tempe- 
rature of 1300° for any length of time without losing its 
tenacity if hydrogen is kept diffusing through the hot metal. 
It seems not impr -obable that this is a case in which the mobile 
and amorphous phases result from the mechanical interference 
of gaseous molecules with the phase transformation. 
54. In a similar way it may be found that to the evolution 
ot hydrogen from a mass of cooling iron which takes place 
when a temperature of 850° is reached, is due the hardness 
which is believed by Osmond to be an intrinsic quality of 
iron above the first arrest-point in the cooling curve, 
55. The coexistence of the two phases in the same mass of 
metal may explain the variety in the texture of specimens 
of pure metal which have been subjected to different methods 
of working. In hammering, tbe crystalline aggregates are 
flattened and spread out, and with their covering films of the 
hardened phase may form a laminated or flake-like structure, 
In rolling or wire-drawing these flakes are elongated longi- 
tudinally, thereby producing a more fibrous structure. 
56. MM. Osmond, Frémont, and Cartaud +t, from a study 
of the modes of deformation and rupture of iron and soft steel, 
have been led to the conclusion that the behaviour of these 
metals under overstrain demands that they should possess 
simultaneously three types of structure, amorphous, cellular, 
* “The Action of Ammonia on Metals,” Beilby and Henderson, Chem, 
Soc. Journ vol. lxxix. p. 1245. 
+ Revue de Métallurgie, January and April, 1904, 
