6 
L. J. H. Teakle and H. E. Hill. 
Tests were made with superphosphate and also with ground rock phos- 
phate from Nauru Island, Christmas Island, Kosseir and Sofaga. In con- 
tact with superphosphate, damage always occurred but the extent varied 
with the nature of the superphosphate and the temperature. Untreated 
rock proved to be entirely inert both when in contact and when the jute 
was in the vapour phase. There is no doubt that the active agent is 
liberated as a result of the treatment with sulphuric acid. 
{iii) Relationship Between Temperature' and Severity of Damage. 
This section of the investigation dealt with the effect of temperature 
on the different types of superphosphates and on superphosphates manu- 
factured from rock phosphate to which chlorides had been added. 
Enquiries and preliminary investigations had indicated that tempera- 
ture was an important factor in the deterioration of jute materials and that, 
in the vapour phase, damage only occurred above a certain temperature. 
Investigations on jute twine were carried out in the laboratory under con- 
ditions ranging from room temperature (21° C.) to an oven temperature of 
75°C. and the results are set out in Table 2. 
TABLE 2. 
Temperature. 
°C. 
Superphosphate. 
Nauru, t 
Christmas. f 
Kosseir A.{ 
Sofaga A.J 
Contact. 
Vapour. 
Contact. 
Vapour. 
Contact. 
Vapour. 
Contact. 
Vapour. 
Room Temperature 
45 
50 
60 
70 
75 
lbs. 
32 
26 
18 
7 
4 
3 
lbs. 
41 
35 
40 
33 
14 
8 
lbs. 
39 
32 
29 
15 
5 
2 
lbs. 
40 
36 
38 
35 
33 
21* 
lbs. 
39 
15 
12 
1 
1 
lbs. 
46 
37 
43 
18 
9 
lbs. 
46 
21 
7 
2 
lbs. 
50 
32 
"46 
20 
Free Acidity % H 2 S0 4 .... 
0-6 
1*6 
0-9 
1- 
59 
Water Soluble Chloride % 
HC1 
nil 
nil 
0-16 
Oil 
* Very variable duplicates. f Room temperature range 19°C. to 27°C. 
X Room temperature range 18°C. to 22°C. 
Iii this test the two groups of superphosphates were found to behave 
somewhat differently. In the fluoride group, deterioration in contact in- 
creased more or less regularly with increase in temperature, the Nauru 
becoming damaging at about 50°C. and the Christmas Island at about 60°C. 
In the vapour phase no activity was apparent until about 70°C., which 
temperature may be regarded as threshold for excessive damage in this 
gioup. Etching of the glassware in contact with the superphosphate sug- 
gests that hydrofluoric acid is the causative agent. In the chloride group, 
deterioration in contact occurred at a lower temperature both Kosseir and 
Sofaga becoming damaging at about 45°C. The Kossier proved more severe 
and in the vapour phase was damaging at 60° C. Hydrochloric acid, formed 
by the action of sulphuric acid on the original chloride, appears to be the 
causative agent. 
