12 
L. J. H. Teakle and H. E. Hill. 
TABLE 9. 
Tensile strength of jute 
Rock. 
Proportion 
of acid 
Free 
Aciditv 
Water 
Soluble 
twine in contact with 
superphosphates (lbs.) 
used in 
% ' 
Chloride 
manufacture. 
h,so 4 . 
(%HC1). 
45°C and 
55°C. 
70°C. 
55°C 
Nauru ... 
100 
117 
less than 
24 
8 
95 
1-27 
001 
30 
2 
90 
1-02 
31 
3 
85 
0-70 
27 
4 
45°C. 
Christmas 
100 
204 
less than 
29 
16 
95 
1-47 
001 
35 
14 
90 
1*34 
34 
14 
85 
1 07 
38 
11 
Kosseir ... 
100 
1 *24 
016 
13 
1 
95 
1-22 
16 
1 
90 
1 14 
17 
1 
85 
1-22 
10 
1 
Sofaga ... 
100 
1-59 
Oil 
21 
2 
95 
1-44 
17 
3 
90 
1-29 
25 
1 
85 
110 
14 
2 
Damage in the vapour phase occurred only with the Kosseir and Sofaga super- 
phosphates at 70°C. 
DISCUSSION AND CONCLUSIONS. 
(1) Damaging Agents. 
The tests reported above give conclusive evidence of the damage to jute 
materials by superphosphate under a range of conditions. The damage 
results in brownish-reddish discoloration of the fabric, loss of tensile strength 
and, in cases of severe damage, extreme brittleness. 
The deterioration is due to a number of agents of an acidic character, 
of which hydrochloric, hydrofluoric and excess sulphuric or phosphoric acid 
are the most important. 
Of these, hydrochloric and hydrofluoric acids are the most active — 
hydrochloric being the more severe — and they are responsible for the 
excessive damage which occurs over a short period of time. They are 
occluded in the granules of superphosphate and act very severely on the 
fabric with which they come in contact. They act also in the vapour phase 
as the temperature rises sufficiently to cause a substantial volatilisation,, 
hydrochloric becoming damaging at lower temperatures than hydrofluoric., 
1 he other two acids, sulphuric and phosphoric, probably exert a mild action 
on the fabric in contact and will become severely damaging when this contact 
is prolonged over a long period. 
Temperature is another factor of prime importance. In superphos- 
phates containing hydrochloric acid fabrics in contact are subject to excessive 
