out of well heated magnetite, but with this second ellipsoid further 
phenomena were observed which have not yet been explained-but 
which seem to be of secondary importance. The zero point deduced 
from the mean of the two scale readings differed noticeably from 
the observed zero, while in any one series of measurements at the 
same temperature it remained practically constant. Further — and 
this is more worthy of notice — the deviations differ according to 
the direction of the field. It would clearly be very rash to attempt 
to ascribe to magnetite a hemimorphous symmetry like that of 
tourmaline from this sole observation. It seems more probable that 
some experimental error has here escaped our notice, and this can 
the more readily be accepted seeing that magnetite gives results much 
less regular than those of the metals. The following table contains 
an extract from the observations; the observations for the positive 
and negative directions of the field are given separately. 
TABLE VIII. 
Magnetite, 
t = 15°.8 C. 
Observed zero — calculated zero -j- 0.9 cm. 
+ F ield — Field 
/ 2 (cm. of scale) /* (cm. of scale) 
71.40 71.72 
71.83 72.00 
71.75 72.57 
71.99 72.57 
71.77 72.45 
H, under atm. pressure (20\3 K.) 
79.78 79.88 
80.69 80.79 
80.73 80.96 
80.34 81.10 
80.08 81.37 
H a solidifying (14°.0 K.) 
80.90 81.10 - 
81.12 81.64 
80.96 81.84 
H (gauss) 
8600 
18100 
21800 
23300 
24200 
8600 
18100 
21800 
23300 
24200 
18100 
21800 
24200 
From these numbers follow these ratios of the intensities at 20\3K. 
and 15°.8 C. 
