4 
Journal of Agricultural Research 
Vol. IT, No. i 
QUANTITATIVE ESTIMATION OF THE VOLATILE ACIDS 
The Duclaux method of fractional distillation was employed for the 
quantitative estimation of the volatile acids. 
In order to illustrate fully this method, complete data for one cheese 
will be given. The soluble-acid portion of the distillate from 150 grams 
of this cheese required for neutralization 57.20 c. c. of decinormal barium 
hydroxid, and the insoluble-acid portion, 12.15 c. c. 
> The soluble-acid portion was divided into four fractions, which were 
distilled in the order of numbering. The remaining 10 c. c. of one fraction 
was always added to the succeeding fraction before making up to 110 c. c. 
Therefore, the only acids not taken into account would be in the last 
10 c. c. of the final fraction. These can be readily calculated, since the 
100 c. c. of distillate collected contained all of the caproic, 97.5 per cent 
of the butyric, and 80 per cent of the acetic acid. 
The data for the analysis of the soluble-acid portion are given in 
Table II. A represents the titer of each successive 10 c. c. portion of the 
distillate; B, the sum of these titers; C, the percentage of B in terms of 
the acidity of 100 c. c. of distillate, and D, the corresponding figures calcu¬ 
lated from the Duclaux constants for the combination of acids indicated. 
Table II .—Data for the quantitative estimation of the soluble acids in Roquefort cheese . 
Fraction I . 1 
Item. 
10 c. c. 
20 c. c. 
30 c. c. 
40 c. c. 
50 c. c. 
60 c. c. 
70 c. c. 
80 c. c. 
90 c. c. 
IOO c. c. 
A.... 
3.01 
2. 29 
1.71 
I. 04 
O. 71 
0. 49 
0. 34 
O. 27 
p 
H 
00 
0. 14 
B.... 
3.01 
5 * 30 
7. 01 
8. 05 
8. 76 
9 - 2 5 
9 - 59 
9. 86 
10. 04 
00 
H 
d 
H 
C.... 
2 9 ‘ 57 
52.06 
68. 86 
79.08 
86. 05 
90. 86 
94. 20 
96.86 
98. 62 
IOO. 00 
D_ 
29. 05 
49 - 73 
67. 66 
78. 72 
86.37 
91.64 
94. 42 
96 . 75 
98.76 
IOO. 00 
Fraction II . 3 
A.... 
04 
H 
O 
2. 20 
1. 64 
1. 12 
• 85 
• 65 
•47 
• 36 
.27 
. 19 
B.... 
3. 10 
5 - 30 
6. 94 
8. 06 
8. 91 
9 - 56 
10. 03 
10.39 
10. 66 
10.85 
C... . 
28. 57 
48. 85 
63. 96 
74. 29 
82. 12 
88. 11 j 
92.44 
95 - 76 
98.25 
100. 00 
D... . 
26. l8 
45 * 70 
62. 62 
74.04 
82. 44 
88. 68 i 
92.44 
95 - 6 9 
98. 24 
100. 00 
Fraction III . 3 
A.... 
2.88 
2. 22 
J - 7 1 
I. 32 
1.02 
.82 
• 65 
• 
•37 
*30 
B.... 
2.88 
Ol 
H 
O 
6.81 
8. 13 
9-15 
9- 97 
10. 62 
11. 13 
11. 50 
11. 80 
C.... 
24. 41 
43. 22 
57- 7 1 
68. 90 
77- 54 
84. 49 
90. 00 
94-3 2 
97-45 
100. 00 
D. .. . 
2 3* 45 
41. 64 
57-49 
69. 00 
77.87 
84. 85 
89. 61 
93*83 
97- 2 5 
100. 00 
1 72 parts of caproic and 28 parts of butyric acid; 7.33 c. c. of caproic and 2.85 c. c. of butyric acid. 
3 54 parts of caproic and 46 parts butyric acid; 5.86 c. c. caproic and 4.99 c. c. butyric acid. 
3 40 parts caproic, 55 parts of butyric, and 5 parts of acetic acid; 4.72 c. c. of caproic, 6.49 c. c. butyric, 0.55 
c. c. acetic acid. 
