661 



The observations I to VIII refer to liquid nitrogen, tiie last two 

 to solid nitrogen. The last two columns show that for liquid nitrogen 

 the relation between vapour-pressure and temperature can be success- 

 fully represented by an equation of the same form as for oxygen, 

 with 



A = — 334.64, B = 4.6969, C=~ 0.00476 {p in int. atm.); 

 according to this equation the normal boiling point of nitrogen is 

 T= 77°.3i K. (9 = - 195°.78 C. 



Fischer and Alt ^) give — 195.67 on the hydrogen scale, on the 

 basis of « = 0.0036625. With a = 0.0036627 the result changes to 

 — 195°.66, whence <9 = - 195°.6i C. With the smaller dimensions 

 of their thermometer a smaller accuracy was to be expected. They 

 give their accuracy as being i .05 of a degree'). 



by Travees, Senter and Jaqukrod (London Phil. Trans. A. 200 (1902)) and those 

 of Kameelingh Onnes and Braak, the latter being lower. The former are 

 therefore now only of importance historically. 



1) Ann. d. Phys. (4) 9 (1902) p. 11-19. 



2) The uncertainly in their determination seems to have been larger, for as 



