490 
PROFESSOR HENRY A. MIERS: AN ENQUIRY INTO 
Among other possible causes to which the production of particular vicinal forms 
might be ascribed are-(l) the temperature at which growth is taking place, (2) the 
rate at which the temperature is changing. It became important to examine next 
how far these two factors might contribute to the results observed. 
From the example quoted on p. 479 and from other similar examples we may 
endeavour to trace a connection between the angle of the vicinal form iii^ alum and 
the rate of fall of temperature, o represents the theoretical octahedron lace, y t le 
vicinal plane. 
Series I.—Potash-alum. 
Time. 
i 
Temperature. 
oy (mean). 
oy (actual values). 
12.-30 
15°-5 
O ! 
0 11 
l6| 91 12 j 
1.0 
15-2 
14 
14 . 
1.10 
14-9 
19 16 
1.20 
14-9 
j 13i 
131 ; 
Hence a fall of al)out 0-6° ill 50 minutes gives as average oy = 14 , ranging tr 
9d to 19 minutes. 
from 
_ 1 oi' 
Temperature nearly stationary at 14-9 gives oy — lo^ . 
Series II.—Potash-alum. 
I Time. 
Temperature. 
oy (mean). 
oy (actual values). 
6.30 
6.45 
7.10 
12.30 
o 
17 
15-8 
15 
14-7 
5 12 
I7i 
15 
lit 13 I'l 
15a 19 1 
•i 
144 204 16 i 
rj ’■> ; 
134 134 174 j 
Hence a fall of 2° in 40 minutes gives as average oy — 
minutes. ^ 
Temperature nearly stationary at 147'’ gives oy = 15'. 
Series III.—Potash-cJuni. 
Time. 
Temperature. 
oy (mean). 
oy (actual values). 
2.10 
2.20 
1 
18°-3 
17-9 
0 ib| 
94 
/ / ' 
m 
15 2| Hi- 
— 
Hence a fall of 0-4° in 10 minutes gives as average oy = 10', ranging from 
2| to 
15 minutes. 
ctco 
