1050 
the higher latitudes. A difference of Om4 in 7’ corresponds to a 
difference of 0.00006 in 4 o. Therefore, if we had used for each 
latitude its own value of w or o, only the last decimal of ”/, would 
have been affected. In that case, however, we must also dismiss the 
assumption 5, = 0. Of the true value of B, we know nothing, but 
we can assert with considerable certainty that it will be of the same 
order of magnitude as the difference between the northern and 
southern rotations, i.e. that it will, like the other causes of uncer- 
tainty discussed above, not exceed the fifth decimal place. 
The deviations from the ellipsoid are, of course, far beyond the 
reach of direct micrometrical measures. In fact they are always 
below O".01. The effect on the times of the phenomena of the satel- 
lites is, at latitude 60°, O8.034 for satellite L and 05.070 for satellite 
IV, which also is beyond the accuracy of the observations. Thus 
for all practical purposes we can treat the surface of Jupiter as a 
true ellipsoid. 
Chemistry. — “The Allotropy of Cadmium V”. By Prof. Ernst 
Coner and W. D. HELDERMAN. 
The heat of Transformation in the reaction Cd(a) 2 Cd(y). 
1. As we pointed out some time ago in our sixth communication 
on the thermodynamics of standard cells,*) in calculating the chemical 
energy of the Weston cell we have to take into account that cad- 
mium is able to exist in different allotropic moditications.. While 
this problem will be treated later in full, it may be pointed cut 
here that it is very important to know the quantity of heat which 
is involved in the reaction 
Cd(a) = Cd(y). 
The investigations to be described here have reference to this 
problem. 
2. Up to the present such a heat of transformation of a metal 
has only been determined in one single case. Some months ago 
BRONSTED °) carried out some measurements on the heat of the trans- 
formation 
grey tin — white tin. 
1) Chem. Weekblad 11, 740 (1914). 
2) Zeitschr. f. physik. Chemie 88, 479 (1914), 
