The Trials of Cream Separators at Doncaster. 
519. 
NOTE ON THE EFFICIENCY OF SEPARATION. 
The extent to whicli each machine was able to effect the 
removal of the cream from the skim-milk was made an important 
feature in these trials. Accordingly, weighed quantities of milk 
were given out, its quality being tested by analysis, the resulting 
products severally weighed, and the skim-milk subsequently 
analysed to see how much butter-fat was left in it. In Table 
II. (p. 507) are given the results obtained. One item, however, 
that under the heading " Loss, &c.," requires some explanation. 
In this is included, not only what was actually missing, i.e., 
lost by spilling or evaporation, but also what was left in the 
drum or bowl of the separator. The trials varied in duration 
from twenty minutes to half an hour, or, in the case of the 
power machines, somewhat longer. Hence, in calculating the 
quantities per hour, the amount left in the drum has been 
reckoned more than once, although it is clear that had the 
operation gone on uninterruptedly for the full hour there would 
have been at the end only one and the same quantity as at the 
close of the shorter run. This makes the loss appear higher 
than it would otherwise be. 
In two cases, No. 1237 (hand) and No. 1234 (power), there 
was at the first of the trial runs a leak in the machine, which 
caused an abnormally high loss to appear. This was remedied 
at subsequent trials. 
Hand Machines. — For testing the efficiency of separation, 
one lot of milk was taken and thoroughly mixed in a large tank, 
quantities being weighed out from it to the different machines, 
according to their capacities. The whole-milk gave on 
analysis : — 
AVater ....... 8772 
Biitter-fat 3-41 
Solids-uot-fat ...... 8-87 
100-00 
The observations and records as to quantity separated, &c., 
were taken from three different trial runs on June 17, 19, and 
20 respectively. The variations of temperature shown in the 
table are due to different temperatures being used in different 
trials. The results show very perfect separation indeed. With 
six out of the seven machines the percentage of butter-fat left in 
the skim-milk fell into the second place of decimals, and, as will 
be seen, practically 98 per cent, of the butter-fat in the milk 
was extracted by them. The most perfect separation was that 
effected by the " Victoria " machine, and the result is the best 
