WEARING QUALITIES OF SHOE LEATHERS. 
in the tan liquor — is not a material factor in the wear, provided the 
leathers have been well tanned. The time of tanning varied from an 
average of 151 days for oak to 92 days for chestnut, hemlock- tanned 
sole leather being intermediate, with an average of 99 days. 
Effect of Glucose and Epsom Salts Content. 
To study the effect of glucose and epsom salts on the wear of sole 
leather several tanners prepared special lots in which the glucose and 
epsom salts content differed from that in leather of their regular 
tannages, the other factors being kept as constant as possible. A 
comparison of the wear of these leathers is made in Table 3. 
Table 3. — Effect of glucose and epsom salts content on wear of sole leather. 
Lot 
No. 
Description of leathers. 
Oak tannage: 
Regular 
Special (same as lot 
1 except lightly- 
rolled and low in 
glucose and salts). 
Special 
Regular (same as 
lot9exceptlowin 
glucose and salts). 
Chestnut tannage: 
Regular 
Special (same as lot 
13 except lower in 
glucose) 
Regular 
Special (same as lot 
24 except highly- 
oiled and low in 
glucose and salts). 
Hemlock tannage: 
Regular 
Special (same as lot 
29 except un- 
bleached and low 
in glucose and 
salts) 
Regular 
Special (same as lot 
32 except low in 
glucose and salts). 
No. of 
soles. 
20 
20 
Composition of original leather (moisture-free basis). 
Total 
ash. 
Petro- 
leum- 
ether 
ex- 
tract. 
Per 
cent. 
1.46 
.70 
2.50 
.54 
2.02 
1.59 
1.19 
Per 
cent. 
3.37 
4.65 
1.93 
1.89 
1.78 
3.85 
1.79 
7.48 
2.33 
2.62 
2.20 
2.25 
Un- 
com- 
bined 
tan- 
nin. 
Per 
cent. 
14.59 
13.11 
11.84 
13.59 
11.39 
12.79 
16.56 
14.54 
14.51 
13.85 
14.47 
14.79 
Non- 
tan- 
nins. 
Per 
cent. 
12.91 
6.50 
15.69 
6.84 
12.52 
8.79 
11.94 
6.50 
14.95 
4.68 
13.87 
10.92 
Water 
solu- 
bles. 
Per 
cent. 
27.50 
19.61 
27.53 
20.43 
23.91 
21.58 
28.50 
21.04 
29.46 
18.53 
28.34 
25.71 
Ep- 
som 
salts. 
Per 
cent. 
3.11 
.12 
2.77 
.12 
1.49 
1.79 
1.73 
.55 
4.54 
.27 
4.15 
Glu- 
Per 
cent. 
2.61 
.37 
7.79 
1.11 
5.53 
2.75 
4.11 
.22 
4.82 
Hide 
sub- 
stance 
Per 
cent. 
40. 25 
44.43 
40.21 
44.66 
45. 00 
45.58 
44.56 
45. 56 
39.95 
48.41 
38.86 
Com- 
bined 
tan- 
nin. 
Per 
cent. 
28.75 
31.20 
30.19 
32.89 
29.15 
28.85 
24.89 
25.67 
28.08 
30.32 
30.21 
31.11 
Aver- 
age 
days 
wear 
per 9 
irons. 
85 
s2 
73 
i Also contained 1.73 per cent of barium chlorid. 
Differences in composition of certain other regular brands of leather 
permit another comparison showing the effect of the glucose and 
epsom salts content on wear. 
Data secured on 90 soles from 5 lots, consisting of only regular 
brands of sole leather having less than a total of 3 per cent of glucose 
> and epsom salts, were assembled. The total glucose and epsom salts 
^) content varied from 1.23 to 2.99 per cent and averaged 1.95 per cent 
The average days wear per 9 irons for all lots was 80. 
Data secured on 249 soles from 12 lots, consisting of only regular 
brands of sole leather having more than a total of 7 per cent of glucose 
and epsom salts, were assembled. The total glucose and epsom salts 
content varied from 7 to 11.08 per cent and averaged 8.92 per cent. 
The average days wear per 9 irons for all lots was 80. 
Averages from Table 3 alone indicate 8 per cent greater wear for 
the loaded leathers. In this same comparison, however, two sets 
85513°— 24 2 
