Alloys qf Ferro-Manganesi and Copper. 



475 



The influence of temper upon the temperature-coefficient of 

 a number of similar alloys was investigated by the method 

 just described. The alloys showed, when hard rolled, a co- 

 efficient very near to zero, sometimes positive, sometimes 

 negative. After annealing at 300° to 400° a well defined 

 negative coefficient, after annealing at a red heat, a still larger 

 positive coefficient, was developed. It was found that the 

 positive coefficient produced by annealing, could be reduced 



iin by rolling the alloy. Table IY shows the character of 

 the results obtained. They were verified in every essential 

 detail by frequent repetitions. 



Table IV. 



Influence of alternate annealing and hardening upon the temperature-coefficient. 



Alloy No. 7. (Copper, 80'40#, Ferro-manganese, 19'60#). 

 Condition of the alloy. Coefficient (20°— 100°). 



Hard + '000022 



Partially annealed — -000032 



Thoroughly annealed. + -000066 



Re-rolled (hard). + -000021 



Again annealed +"000045 



To determine the relation of the composition of these 

 alloys to their temperature-coefficients, Mr. Blood tested twelve 

 specimens, in which the amount of copper ranged from 70 per 

 cent to 99*5 per cent, and also the copper itself from which 

 the alloys were made. The percentage of copper present in 

 each test-piece was determined to within one hundredth of one 

 per cent, by the method of electro-deposition. The results of 

 these determinations are incorporated in Table Y. 



Table V. 









Temperature-coefficient, 



;20M00 ). 





Percentage 











Percentage of 



of Ferro- 



Sp. resistance 









copper. 



manganese. 



(copper=lU0) 





Alloy semi- 











Alloy hard. 



annealed. 



Alloy annealed. 



100-00 



o-oo 



1-00 



•003202 







9958 



042 



107 



•002579 







9926 



0-74 



119 



•002167 







91-88 



8-12 



11-28 



•000138 





•000184 



91-03 



8-97 



11-74 



•000120 







88-97 



11-03 



14-07 



•000065 







86-98 



13-02 



20 40 



•000016 



-•000021 



•000080 



83-72 



16-28 







•000010 





•000023 



80-88 



19-12 



30-38 



•000012 





•000046 



80-40 



19-60 



27-50 



•000022 



-•000032 



•000066 



7780 



22-20 









•000053 



77-20 



22-80 



35-90 



-•000012 





•000010 



70-65 



29-35 



45-10 



-•000024 





•000021 



Am. Jour. Sci.— Third Series, Vol XXXIX. No. 234.— June, 1890. 

 31 



