588 
On a New Method of Testing Milk. 
The skim-milk from the sample No. 4 was likewise watered 
bj the addition of 10, 20, and 30 measures of water to 100 
measures of skim-milk. 
Thus watered the three samples of skim-milk had the following 
specific gravity : — 
Skim-Milk from Sample No. 4 with 
10 Per Cent, 
added Water. 
20 Per Cent, 
added Water. 
30 Per Cent, 
added Water. 
1-0315 
1-029 
1-027 
Feser's lactoscope showed : — 
per cent. 
If 
per cent. 
n 
per cent. 
1 
Although Feser's lactoscope in these experiments does not 
appear to have given very accurate results, it will be seen that 
the instrument shows most distinctly whether new or skim-milk 
has been watered. 
On the 31st of July, 1879, I received a sample of milk from 
Sir Henry Dashwood, Kirtlington Park, Oxon, and analysed it 
on the same day on which I received it, and at the same time 
tried some experiments with Feser's lactoscope. 
The composition of this milk was as follows : — 
Water 86-85 
Pure butter-fat 3-80 
*Caseine (curd) 3-0 
Milk-sugar 5-56 
Mineral matter (asli) 0*73 
100 -cc 
*Containing nitrogen 0-49 
Specific gravity at 20 ■ 6° C 1-032 
Percentage of cream by volume after standing\ ^ . ^ 
24 hours / ^ " 
The preceding analysis represents fairly the average compo- 
sition of good genuine country milk. The milk was sent to me 
by rail in a small tin only half filled, and evidently had been 
shaken about a good deal before reaching me, which accounts for 
its throwing up only 5 per cent, of cream, although it contained 
nearly 4 per cent, of butter-fat. 
In this milk Feser's lactoscope showed 3i to 3| per cent, of 
pure butter-fat, which agrees closely with the actual proportions 
of fat as determined by chemical analysis. 
After the addition of 10, 20, and 30 measures of water to 
