226 REPORTS ON INVE;STIGATI0NS AND PROJElCTS. 



Campbell, William, Columbia University, New York, N. Y. Grant No. 1 79. 



Study of the eff-cct of heat treatmoit 2ipon the tnicrostnictiire and physical, 



properties of steel and iron. (For previous reports see Year Book No. 



3, p. 124, and Year Book No. 4, p. 249.) $1,500. 



Abstract of Report. — The work of last year has been continued by the 



examination of the series of high-carbon steels (0.7 to 2.0 per cent carbon) 



after quenching from temperatures between 600° and 1400° C. A series of 



18 steels, carbon o.i to 1.5 per cent, is being investigated as to overheating 



and refining by heat treatment. 



Six weeks have been spent at a large iron and steel plant, studying, for 

 the most part, the finishing temperatures of structural and rail steel with a 

 Wanner optical and a Le Chatelier thermo-electric pyrometer. The average 

 finishing temperature for 85-pound rails was 1105° to 1145° C, for 8-pound 

 rails 1050° to 1100° C, for low-carbon structural steel of small dimensions 

 about 985° C. The number of temperature readings obtained was very 

 great indeed, and numerous specimens were saved for further investigation 

 along microscopic lines. 



Carhart, Henry S., University of Michigan, Ann Arbor, Michigan. Grant 

 No. 151. Detenninatioji of the electromotive force of Clark and Weston 

 cells, etc. (For previous reports see Year Book No. 3, pp. 124-126, and 

 Year Book No. 4, p. 250.) $500. 



Abstract of Report. — During the summer and autumn of 1906 five series of 

 determinations of the electromotive force of the Weston normal cell have 

 been made in conjunction with my colleague, Prof. George W. Patterson. 

 The apparatus used was the absolute electrodynamometer described by 

 Patterson and Guthe in the Physical Review, vol. 7, p. 257, and by Guthe in 

 the Bulletin of the Bureau of Standards, vol. 2, No. i, p. 33. Our instru- 

 ment differs from the one described by Guthe chiefly in the fact that the 

 suspending bronze wire is about two and a quarter meters long as compared 

 with one of about one-third that length used by Guthe. 



The current measured by the electrodynamometer is measured simultane- 

 ously by means of a standard resistance and a Wolff's potentiometer, assum- 

 ing a value of the electromotive force of a Weston standard cell set up about 

 three years ago. Then the ratio of the current measured by the electro- 

 dynamometer and the apparent current measured by the standard resistance 

 and the potentiometer is the same as the measured electromotive force and 

 the electromotive force assumed. 



The results for the five series must be taken as preliminary only. The 

 elaborate calculation to find the correction for the irregularities of the wind- 

 ing of the stationary coil has been gone over but once. It must be recalcu- 

 lated as a check. Further investigation of the period of the suspending wire 



