The Deterioration of Jute Materials. 
7 
The effect of chlorides in superphosphates on the tensile strength of 
jute twine was further tested on an experimental scale by adding various 
chlorides to Nauru rock phosphate prior to acid treatment in the manufacture 
of superphosphate. Sodium chloride, calcium chloride and magnesium 
chloride were used but, as the results were similar, only figures for sodium 
chloride are given. These are shown in Table 3, where they are compared 
with superphosphate from Kosseir rock. 
TABLE 3. 
Chloride Content (as % HC1). 
Temperature. 
Nauru 
phosphate. 
Nauru phosphate plus 
sodium chloride. 
Kosseir 
phosphate. 
None. 
0 102. 
0-94. 
' 016. 
lbs. 
lbs. 
lbs. 
lbs. 
50°C. contact ... 
31 
10 
1 
12 
vapour ... 
42 
43 
16 
43 
60°C. contact ... 
18 
2 
zero 
1 
vapour ... 
40 
29 
6 
18 
70°C. contact ... 
12 
2 
zero 
1 
vapour ... 
39 
40 
9 
9 
The results show conclusively the extremely damaging effect of super- 
phosphate made from rock containing chlorides. Excessive damage occurred 
both in contact and in the vapour phase and the degree of damage increased 
as the concentration of the chloride was increased. This confirmed that 
hydrochloric acid liberated by the action of the sulphuric acid on the 
chloride in the course of manufacture is the causative agent in the case of 
superphosphate made from Egyptian rock. 
Tests on jute materials were also made with aqueous solutions of 
hydrochloric, hydrofluoric and nitric acids and sodium fluosilicate and with 
a solution of sodium fluosilicate in 5 per cent, sulphuric acid. The tensile 
strength of the jute twine suspended in the vapour phase above these 
substances for three days and four nights at 70° C. and of dry and moist 
twine were as follows : — 
3 per cent hydrochloric acid 
3 per cent hydrofluoric acid 
6*5 per cent, nitric acid 
Sodium fluosilicate aqueous solution 
Sodium fluosilicate in 5 per cent, sulphuric acid 
Dry twine 
Twine suspended above distilled water 
lbs. 
zero 
27 * 
7 
37 
14 
31 
45 
*The bottle containing the hydrofluoric acid was waxed to protect the glass. How- 
ever, the wax melted and floated on the solution so that 27 lbs. may not be an accurate 
figure for the damaging effect of hydrofluoric acid on the jute fabric. 
