42 STORRS AGRICULTURAL EXPERIMENT STATION. 
LABEL RATE: 
A Comparison of the Gravimetric Analyses and of Babcock Tests 
of Skim Milk. 




PER CENT. OF FAT. 



SAMPLE NUMBER. , STEAM TURBINE TESTS. 
Gravimetric | 
Analyses. | 
| 17.6 ec. Acid. aa 
No. I, - . : = - - / iA y. .O45 .060 
NOs re. ts 5 fe © : - | .143 | 2055 .055 
NO ve 99 Sce - - - - - .149 | .O15 .030 
ING ath 4 - - - - - | Bo nel 025 .055 
Now 5s. - - - - - | REST / .080 080 
NOs sO a= - : - - - | 118 | .060 .090 
INGOs Talis - - - - | rrAay | .055 .085 
Noces.: i - - - - - | ,213 | .065 .OgO 
NGsno0? - - - - - | 2135 | .020 .035 
No. TO, ~ - - - - - | 158 .040 | .050 
ea Se ees eal elt hs ee ere lle At, | POR a ek Sek 
| 
Average, - 2 2 ee : 144 | .046 | 063 



These results show that even when an excess of acid was used 
the Babcock readings were lower than gravimetric analyses. 
In the testing of samples of skim milk, it has been recom- 
mended to whirl the bottles in a steam-heated tester in which 
the temperature rises to nearly 200° F. The excess of acid, 
the long Whirling, and the high temperature all aid in the 
separation of the last trace of fat. 
The Wisconsin Station Report (1903) gives a comparison of 
results of gravimetric analyses and of Babcock tests of skim 
milk. . The average gravimetric analyses of ten samples of 
skim milk was 0.077 per cent. of fat. With the Babcock 
method, when an excess of acid was used and the tests run for 
six minutes at a temperature of 200° F., the results were 
0.056 per cent., and at a temperature of 140°, 0.03 per cent. fat. 
HRRORS IN READING BABCOCK TESTS. 
The readings of Babcock tests should be made at a tempera- 
ture of 140° F. In turbine testers that prevent the free escape 
of steam, milk samples may come .2 or .3 per cent. too high, 
and cream samples as much as 1 per cent. too high in some 
cases. The effect of differences in temperature of the fat on 
