1659 
a solution of one molecule of fructose in 0.11 m. H,BO, the following 
result was obtained : 
R—= 400 {2 ; Cap. = 0.1661. R= 400 22 ; Cap. = 0.1629. 
R di 1 d | "7 | 1 | 
t Seale | KX!08 | AEK || ¢ | a | KX108 | K+K 
5 = pee Î 
10 | 511 400 10 | 504 | 403 | 
14 493 429 0.040 | 14 | 488.5 | 429 0.036 
18 | 481 | 450 | 0.041 || 18 | 476 451 0.039 
23 472.5 465 0.039 || 23 466.5 469 0.041 
30 | 464.5 | 481 | 0.042 || 30 | 461 480 0.039 
| 
35 | 462 486 0.041 | 40 | 455 491 0.042 
| \| | 
| « | .460 490 wo | 452 496 
| | 
Hence, there is a fairly satisfactory agreement between the con- 
stant of the mutarotation and that of the conductivity change; both 
are still considerably higher than that of the muta-rotation of the 
a-fructose at O° in pure water. (Found = 0.0124). 
0.5 mol. fructose in 0.02 mol. H,BO, gave as constant for the 
conductivity change 0.032. 
From our measurements it will be seen that the conductivity at 
the transformation c—3-fructose rises; from this it follows that in 
the ordinary fructose the distribution of the hydroxyl-groups is less 
favourable than in its mutarotation isomeride. With this the configuration 
of the two fructoses is now known; it is indicated in the above symbols. 
Delft, March 1916. 
Physics. — “The viscosity of liquefied gases. IV. Apparatus and 
method. V. Preliminary measurements on liquid mixtures of 
oxygen and nitrogen.” By Prof. J. E. VerscnarreLt and Dr. Cu. 
Nrcatse. Communication 1495 from the Physical Laboratory 
at Leiden. (Communicated by H. KaMERLINGH ONNES). 
(Communicated in the meeting of March 25, 1916). 
IV. Apparatus and method. 
1. Introduction. 
In the three preceding communications of this series (Comm. 1485 
c and d) one of us has developed the theory of the rotational oscil- 
lations of a sphere in a viscous liquid, with a view to an experi- 
mental investigation concerning the viscosity of liquid gases at low 
temperatures, especially of liquid hydrogen, which we have under- 
