On a New Method of Testing Milk 
587 
In these trials Feser's instrument showed the percentage of 
fat a little under the mark in the case of samples No. 1 and 
No. 3, and slightly too high in sample No, '4 ; whilst in the 
milk No. 2 the indications were decidedly below the real amount 
of fat. 
After removal of the cream, the skim-milk produced from these 
samples was analysed, and the following results were obtained : — 
Composition of Skim-Milk. 
No. 1. 
Kg. 2. 
No. 3. 
No. 4. 
91-33 
-45 
8-22 
90-87 
1-01 
8-12 
90-82 
1-58 
7-60 
89-03 
1-84: 
9-13 
100-00 
100-00 
100-00 
100-00 
"Specific gravity at 18° C 
Feser's lactoscope showed : — 
Percentage of pure butter-fat 
1-032 
per cent, 
a to 1 
1-0305 
per cent. 
2 to 2i 
1-0285 
per cent. 
■^4 
1-034 
per cent. 
2 to 2i 
In the case of skim-milk it appears that Feser's indications 
were too high. The skim-milk from milk No. 2 was rather 
more acid than the three remaining samples ; this probably 
accounts for Feser's lactoscope showing a larger percentage of 
fat than the skim-milk really contained. When skim-milk turns 
slightly acid on keeping, without coagulation, I find that it 
becomes more opaque than it is in a fresher condition, and for 
this reason the lactoscope in this case gives the percentage of 
fat too high. 
In the next place I purposely watered some of the milk No. 4, 
by adding to 100 measures 10 measures of water in one trial, 
20 in another, and 30 in the third. 
On standing for eighteen hours the three samples of watered 
milk threw up the following percentages of cream : — 
Milk No. 4 watered with 
10 Percent, 
added Water. 
20 Per Cent, 
added Water. 
30 Per Cent, 
added Water. 
11 
101 
9 
Feser's lactoscope sliowed in these watered 
milks : — 
per cent. 
•ih 
per cent. 
3i 
per cent. 
2i 
