430 
Journal of Agricultural Research 
Vol. II, No. 6 
Milk fat is such a complex substance that the exact differences in com¬ 
position between the milk fats of the various mammals are difficult to 
determine. That there are marked differences has been shown by Pizzi 
(1894), who determined the Reichert-Meissl number of the milk fat of 12 
mammals. His results are summarized as follows: 
Table II.— Reichert-Meissl number of the milk fat of 12 mammals , according to Pizzi 
Mammal. 
Reichert- 
Meissl 
number. 
Mammal. 
Reichert- 
Meissl 
number. 
Mammal. 
Reichert- 
Meissl 
number. 
Sheep. 
32.89 
28. 60 
27. 00 
26. 18 
Rabbit. 
16. 06 
I 3-09 
II. 22 
4 . 4 O 
Rat. 
2.97 
I. 65 
I. 42 
I. 21 
Goat. 
Ass. 
Sow. 
Cow. 
Mare. 
Woman. 
Buffalo. 
Cat. 
Doe. 
Such differences in the volatile-soluble acids as are shown in the above 
results suggest differences in the relative proportions of the other acids 
present. 
A thorough search of the literature of the subject has not revealed any 
report of a complete analysis of sheep’s-milk fat. Fodor (1912) deter¬ 
mined some of the chemical constants through an entire period of lacta¬ 
tion. He obtained the fat by separating it from fresh Liptauer cheese 
made from sheep’s milk. Martin (1914) examined the fat of milk known 
to be genuine sheep’s milk from the locality of Roquefort at weekly 
intervals from January 28 to June 2. The results of these two investi¬ 
gators, together with the results of Eckles and Shaw (1913) for two 
breeds of dairy cows, are summarized in Table III. 
Table III. —Chemical constants of the fat of sheep's and cow's milk 
Investigator. 
Source of milk fat. 
Reichert- 
Meissl 
number. 
Iodin 
number. 
Saponifi¬ 
cation 
number. 
Polenske 
number. 
Caprylic-acid 
number 
(Dons). 
Fodor. ... 
Martin . . . 
Eckles and 
Shaw. 
Do. 
Liptauer cheese. 
Sheep’s milk. 
26. 84 
28. 48 
26.73 
26. 28 
39-3 
231- 5 
231- 58 
228. 9 
229. I 
4. 40 
2.9 
Jersey milk. 
3 °- 52 
34. 20 
Holstein milk. 
The Polenske and caprylic-acid numbers are figures based upon arbi¬ 
trary procedures and are proportional to the volatile-insoluble acids. 
Polenske states that his number for a cow’s-milk fat having a Reichert- 
Meissl number of 26 to 27 is 1.9 to 2. Dons gives the caprylic-acid 
number for cow’s-milk fat as 1.75. 
From these chemical constants it appears that the quantity of volatile- 
insoluble acids of sheep’s-milk fat is about double that of cow’s-milk fat. 
The oleic-acid content of the former is also greater than that of the latter. 
VOLATILE ACIDS OF ROQUEFORT-CHEESE AND COW’S-MILK FAT 
Four Roquefort cheeses of different brands and ripened as little as any 
to be found in the market were procured and the fat separated by the 
Schmidt-Bondzynski method. In order to remove any free fatty acids, 
