Sigh Temperatures. 



183 



cylindrical glass vessel, with double walls enclosing a vacuum, 

 such as is commonly used for liquid air (Prof. Dewar's design), 

 was filled with olive oil. Into the oil dipped a porcelain tube 

 with two spiral furrows upon the outer surface, carrying coils 

 of tare constantan wire. Inside the tube a turbine was 

 inserted and held in place above and below with brass clamp- 

 ing rings. The stirrer and heating coil were thus in one piece 

 and could be introduced into any insulating bath at pleasure. 

 A vessel with a vacuum jacket is preferable however, on 

 account of the very small quantity of electrical energy required 

 to heat it, even when the walls are left unsilvered for reading 

 a completely immersed thermometer. With 1*2 1. of oil only 

 100 watts were necessary to maintain a temperature of 250°. 

 Although in using this apparatus we did not have an accident 

 from explosion of the vessel, still, as this now and then occurs 

 with such vessels at low temperatures without any apparent 

 cause, it is well to make provision against possible personal 

 injury in such an event. Table XV contains the comparison 

 of thermo-element and gas thermometer in the nitre bath. The 

 bulb was filled with nitrogen under a pressure of 471-8i mm 

 at 0°. 



Table XV. 

 Observations in the Nitre Bath. 





t ■ 



e 2 (MV) 



Obs.— 

 Calcul. 





t 



e 2 (MV) 



Obs.— 

 Calcul. 



Feb. 6 



340-7° 



2639 



-0-8° 



Feb. 8 



395-8° 



3153 



— 0-8° 





340-5 



2635 



— 0-5 





395-8 



3151 



— 06 





387-5 



3076 



— 0-9 





492-6 



4082 



-0-7 





386-9 



3071 



— 1-0 





492-8 



4084 



-0-7 





439-8 

 439-8 

 501-3 

 500-9 



3573 

 3572 

 4171 

 4168 



— 1-0 



— 0-9 



— 1-3 

 -1-4 



March 29 



359-6 

 359-5 

 400-5 

 402-4 



2803 

 2802 

 3195 

 3217 



+ 0-4 

 + 0-4 



— 0-6 



— 1-0 



Feb. 8 



267-4 



1970 



— 0-6 





498-5 



4140 



— i-0 





291-6 



2191 



— 0-8 





498-3 



4139 



— 1-1 





291-7 



2193 



— 0-9 











4. Formulae for Thermo-elements. 



In a previous paper* we were able to show that the relation 

 between the thermo-electric force and the temperature in 

 metals of the platinum group together with gold and silver 

 could be represented within wide limits with an accuracy of 

 ± 1° by a function of the second degree. 



* Ludwig Holborn and Arthur L. Day, this Journal (IV), viii, 46, ] 899. 



