Simpson — Coniributions to Mineralogy of IV.A. 
61 
its water. This constituent was found to ])e very readily lost as 
the following figures show : — 
Dehydration of Mulgine FcrrimoJybdite. 
Total 
time. 
Water loss per 
cent. 
Colours. 
hours. Individual 
Total 
Stage I. 
Picric yellow 
In balance 
2 
1.87 
1.87 
case with 
3 
.50 
2.37 
CaCb 
6 
1.33 
3.70 
12 
2.12 
5.82 
100 
2.93 
8.75 
365 
1.37 
10.12 
440 
.08 
10.20 
Deeper yellow 
Stage II. 
10.72 
Steam oven 
2 
.52 
at 100° 
8 
.38 
11.10 
11 
nil 
11.10 
Dark yellow 
Stage III. 
Air oven 
1 
1.50 
12.60 
at 125° 
2 
.65 
13.25 
4 
.72 
13.97 
12 
3.48 
16.45 
14 
.05 
16.50 
Yellowish green 
Stage IV. 
19.65 
Air oven 
1 
3.15 
at 200° 
3i 
.22 
19.87 
5 
.05 
19.92 
Olive green 
Stage V. 
Air oven 
1 
.23 
20.15 
at 250° 
3 
nil 
20.15 
Olive green 
Very many intermediate weighings were made which are not 
shown in the table. Almost identical figures to those shown 
under Stage 1. were obtained when the mineral was desiccated 
over sulphuric acid. 
It is evident that ferrimolybdite is very susceptible to desic- 
cation, a fact which explains the lower water percentage in B, 
after keeping a few days in the warmer atmosphere of the labora- 
tory. It also explains the lower and variable ratios for H 2 O to 
M 0 O 2 given for the artificial compounds and for the minerals 
from American localities given hy Schaller. The colour changes 
during drvmg were most marked, and have previously bceii noted 
by Schaller in the mineral from American localities. 
