104 



BELL SYSTEM TECHNICAL JOURNAL 

 TABLE I 



T = Top of cast. 

 B = Bottom of cast. 



whether or not consideration of other factors may show it to be unsatis- 

 factory as a wiping solder. 



Plasticity Studies 

 Experimental Procedure 



The plastometer used in the investigation is a modification of the 

 instrument used by Williams ^ in studies on rubber compounds. It 

 has been fully described elsewhere ^ by one of the writers. A heat- 

 insulated cylindrical steel block provided with heating elements and 

 thermocouples contains a central cylindrical well 2}4 inches (6.35 

 cm.) in diameter and 5 inches (12.70 cm.) deep. The block itself is 

 about 12 inches (30.48 cm.) in diameter, being made large to prevent 

 rapid temperature fluctuations. A flat-bottomed cylindrical plunger, 

 also carrying heating elements and a thermocouple, fits into the well 

 with a small clearance. The load on the plunger may be adjusted to 

 suit the conditions of test. A sample of the material to be tested is 

 placed under the plunger, given 90 minutes to come to temperature and 

 the plunger released and allowed to compress the sample. The 



2 I. Williams, Ind. & Eng. Chem., 16, 262 (1924). 



3 R. L. Peek, Jr., "Parallel Plate Plastometry" (now being prepared for pub- 

 lication). 



