160 H. S. H. WARDLAW. 
also be seen that the first portion of the deposit comes 
down at arate a good deal greater than that of the succeed- 
ing portion. The rate of deposition decreases to a minimum 
and then begins to rise again during the course of about 
four hours’ spinning. In one case the final rate of depo- 
sition was even greater than the first rate of deposition, 
but as a rule the rate of deposition, after passing through 
the minimum, did not rise as high as the first rate in the 
time for which the spinning was continued; it might do so 
if the spinning were continued longer. There is a variation 
in the ash-content of the deposit in the opposite direction 
to the variation in the rate of deposition (see below). 
3. Ash-content of the Deposit. 
The ash of the deposits obtained from milk as described 
above varies somewhat from one milk to another. The 
ashing was performed ina muffle furnace; the rear only of 
the muffle was heated, the porcelain dish containing the 
deposits being gradually moved from the mouth of the muffle 
to the hotter parts. As the deposit formed a thin layer on 
the bottom of the dish, the ashing was very rapid and com- 
plete. The following table gives the ash-contents of a series 
of these deposits. 
Table 1V.—Ash-content of Centrifuge-deposit from Milk. 
Milk. \Weight of Deposit.) Weight of Ash. |Percentage of Ash. 
4 0:4457 gm. 0:0310 gm. 6°94 
6 1:4041 ,, O1001 Fe 713 
9 0:6275 ,, 0-0618'",, 9°85 
10 0°5304 ,, 0:0431 ,, 8:12 
12 1:5251 ,, O-1lot ap ee 
13 1-055!) -,, 0:0913 ,, - 8°65 
15 0:5594 ,, 0:0452 ,, 8:09 
Li 0°6052 ,, 0:0503 ,, 8°32 
22 0°3433 ,, 00257 8°65 
35 0:2070 ,, 0:0180 ,, 8°70 
37 0:1084 ,, O-OL0T 05 9°87 
38 0-1 286 .., 0-01.22... 9°48 
39 0-1339' 5; 0-0120' ,, Oo7T 
4] 0°3634 ,, 0:0247 ,, 6°80 
42 0:2725 ,, OOl32 7°04 
