No. of 
sample. 
Acidity 
(per cent). 
Temperature 
(°C.). 
Time of 
heating 
(minutes). 
Curdled 
= + ; not 
'curdled = — . 
1 
0.711 
65 
+ 
2 
.594 
65 
1 
+ 
3 
. 576 
65 
2 
+ 
4 
.567 
65 
1 
+ 
5 
.554 
60 
2 
+ 
6 
.531 
65-67 
2 
4- 
7 
.513 
65 
2 
+ 
8 
.478 
60 
• 5 
+ 
9 
.450 
65 - 
1£ 
+ 
10 
.441 
66 
1 
+ 
11 
.387 
65 
5 
+ 
12 
.351 
65-67 
2 
+ 
13 
.351 
65 
5 
+ 
14 
.351 
65 
5 
+ 
15 
.342 
78.5 
2 
+ 
10 
.342 
66 
5 
- ' 
17 
.315 
70 
10 
+ 
18 
.315 
70 
5 
- 
19 
.315 
65 
5 
- 
20 
.306 
75 
3 
+ 
21 
.306 
65 
5 
- 
22 
.288 
70 
5 
- 
23 
.261 
65-74 
5 
- 
24 
.252 
100 
1 
- 
25 
.252 
70 
5 
- 
26 
.243 
100 
1 
- 
27 
.243 
72-74 
10 
- 
28 
.243 
65 
10 
- 
29 
.234 
65 
5 
- 
30 
.225 
65-67 
2 
+ 
31 
.198 
65 
5 
- 
32 
1 1 
.180 
65 
5 
— 
* Immediately. 
It will be seen from our results that of those samples of milk 
which coagulated on heating, sample 30 contained the smallest 
amount of acid at the time of coagulation, viz, 0.225 per cent. This 
sample curdled in two minutes at 65°-67° C. It will be observed 
that milks containing from 0.306 to 0.315 per cent of acid curdled 
at temperatures varying from 65°-78.5° C., in from two to ten min- 
utes, and that as a general rule those milks are rhost easily coagulated 
by heat which have the highest acidity. On the other hand, while 
one of the samples having an acidity of only 0.225 per cent curdled 
at 65°-67° C., in two minutes, another sample containing 0.243 per- 
cent of acid did not curdle even on boiling. Thorner (15) found 
the acidity necessary to coagulate milk on heating to be 0.207 per cent. 
On the other hand, Rideal (16) found the amount of acid required 
to effect the coagulation to be somewhat higher than this. According 
to him the tendency to coagulate is not very marked even when the 
