THE VARIATION OF ANGLES OBSERVED IN CRYSTALS. 
491 
Se ries IV. —Animonia-aliim. 
Time. 
Temperature. 
oy (mean). 
oy (actual values). 
9.10 
o 
15-1 
o / 
0 13 
2U 4| 
11.25 
14-5 
18 
174 13 22 191 
1.15 
14-3 
164 
134 19i 
o .3 
Fall of 0‘8° in 240 minutes gives as average oy — 16', ranging from 4f to 22 
minutes. 
Temperature nearly stationary at 14’3° gives oy = I6|-'. 
Series Y^. —Ammonia-alum. 
Time. 
Temperature. 
oy (mean). 
oy (actual values). 
11.15 
12'’-2 
0 21 
21 
24 
181 
12.45 
12-1 
164 
18 
154 
Fall of 0-1° in 90 minutes gives as average oy = 18|'. 
Temperature nearly stationary at 12‘V gives oy = 16V. 
Series Y^I.—Ammonia-alum. 
Time. 
Temperature. 
oy (mean). 
oy (actual values). 
11.30 
o 
18 
5 234 
231 
12.0 
16-3 
204 
224 184 
O xJ 
Fall of 1 ' 7 ° in 30 minutes gives an average oy — 21|'. 
Series VII.—Ammonia-alum. 
Time. 
Temperature. 
oy (mean). 
oy (actual values). 
11.0 
12°-8 
o / 
0 144 
16^ 
13 
11.30 
12-8 
13 
15 
11 
Temperature nearly stationary at 12'8° gives oy = 13|-'- 
3 R 2 
