of Bronzes from Machu Picchu, Peru. 555 



may be determined. The present discussion is intended to 

 convey a rational conception of the connection between defor- 

 mational and recrystallization phenomena from a qualitative 

 standpoint. As far as the present bronzes go, it is possible to 

 detect incipient recrystallization after severe deformation with- 

 out inquiring into the details of the treatment effected. Cases 

 of this sort will be pointed out later. Semi-quantitative 

 conclusions bearing upon subsequent growth of grain seem 

 justified from every point of view. 



It may be remarked that a diagram of this sort may be 

 drawn to represent the condition developed by anneal during 

 a fixed period of time, or by anneal for the period necessary 

 in order to bring about an equilibrium effect. The latter 

 (ideal) condition was kept in mind throughout the foregoing 

 discussion. The former condition would entail displacement 

 of all recrystallization curves without affecting the general 

 principles involved. 



Owing to the difficulty of distinguishing between recrystal- 

 lized and unrecrystallized units, counting data obtained from 

 partially recrystallized conglomerates are not especially useful 

 or significant. It is possible to obtain at first an increase and, 

 later on, a decrease in the number of visible grains as the 

 period of anneal at constant temperature, or as the temperature 

 for constant period of anneal, increases. This does not signify 

 that the individual grains first disintegrate (contrary to 

 thermodynamical requirements) and later coalesce, but that the 

 original strain-hardened grain fragments (each of which is 

 counted as a single unit) are rapidly developing secondary 

 grains in the early stages of the anneal, while, later, coalescence 

 itself constitutes the predominant factor. Such a condition is 

 represented by the curve lettered (a) in fig. 7. This curve 

 represents the number of distinguishable grains after annealing 

 an alloy containing 96 per cent copper at 625° for periods 

 ranging from one half hour to five hours. Beyond one hour, 

 growth is normal, in that the distinguishable grains increase 

 in size and decrease in number. Between one half hour and 

 one hour, however, the reverse effect is encountered. This 

 reversal evidently takes place earlier in the alloy containing 

 94 per cent copper, as indicated by the trend of the curve 

 (b) in this vicinity, while, in the alloy containing 92 per cent 

 copper, it must take place at a still earlier stage of recrystal- 

 lization, since the corresponding curve (c) shows normal growth 

 of grain at the very start. Viewed under the lowest powers, 



