598 Wisconsin Academy of Sciences^ Aris^ and Letters. 
Proximate Analysis 
Ash and silica. The inorganic substance of all the catches 
was determined by first carbonizing the material under exam¬ 
ination with a small flame. Ashing was then completed in an 
electric muffle furnace at a temperature of 500° to 600° C. 
The plant catches as a rule show the highest ash content. The 
algal catch “E” has a much lower ash content^ however^ then 
might be expected by analogy with samples ^'A’’ and 
The ash was taken up with dilute hydrochloric acid, heated 
on the steam-bath and the siliceous residue filtered off. In order 
to remove any silica which might have passed into the filtrate, 
the latter was evaporated to dryness, dried at 120° C., again 
taken up in hydrochloric acid, heated, and filtered through the 
same filter as before. The residue was then burned, weighed, 
treated with sulphuric and hydrofluoric acids in the usual way, 
evaporated and ignited, and the loss in weight calculated as 
silica. 
The ash and silica contents are tabulated below: 
Sample 
Ash 
Silica’ 
A........ 
26.05 
17 90% 
B ............ 
27.16 
20.82 
C......... 
13.98 
2.37 
D...... 
14.51 
0 70 
E.. 
6.52 
0.17 
154........ 
7.62 
0.07 
5138(2)...,..... .... 
41.44 
34.37 
Ether extract. All samples were extracted, with washed an¬ 
hydrous ether in a Soxhlet extraction apparatus for twenty- 
four hours, the extract filtered into a tared dish, the ether al¬ 
lowed to evaporate spontaneously, the residue dried over sul¬ 
phuric acid and weighed. The extracts obtained from the plant 
catches ‘^A,’’ and were quite unlike those obtained 
from the Crustacea catches and and the Daphnia 
catch, number 154, which had all the physical characteristics of 
an oil. The odors of the latter were decidedly those of a fish 
oil. The ether extract from the Daphnia catch solidified on 
exposure to the air, a fact which differentiates it from the 
1 Silica determinations by A. J. Duggan of the Survey. 
2 Determination by N. A. Bailey of the Survey. 
