10 
L. J. H. Teakle and H. E. Hill. 
TABLE 6. 
Superphosphate or 
Superphosphate Mixture. 
Tensile Strength of sacking 1 inch wide (lbs.). 
Amount of precipitated calcium carbonate added. 
None. 
2%- 
4%. 
6%- 
Nauru ... 
110 
150 
Christmas 
129 
129 
144 
136 
Egyptian 
102 
132 
136 
146 
Kosseir ... 
35 
128 
172 
... 
f Christmas 84% . . . 
Mixture ■< Egyptian 14% ... 
128 
150 
152 
... 
(^Limestone 2% ... 
In this table only contact figures are given as, with the exception of 
Nauru superphosphate which for some unaccountable reason showed de- 
terioration, no damage was observed in the vapour phase. The table shows 
the severe damage caused by Kosseir superphosphate in contact with 
jute and, further, confirms the results of stacking tests on the efficacy of 
added calcium carbonate. The weather during this period was not excessively 
hot. 
Standard laboratory tests using jute twine were then carried out on the 
effect of addition of 2% precipitated calcium carbonate to Nauru and 
Christmas Island superphosphates over a range of temperatures from 19° C. 
to 75° C. The results are given in Table 7. 
TABLE 7. 
Tensile strength of jute twine (lbs.) in contact with — 
Temperature. 
°C. 
Nauru Superphosphate. 
Christmas I. Superphosphate. 
Without 
CaC0 3 . 
With 2 per 
cent CaCOg. 
Without 
CaCOg. 
With 2 per 
cent. CaCOg. 
lbs. 
lbs. 
lbs. 
lbs. 
19-27 
32 
38 
39 
40 
45 
26 
37 
32 
42 
50 
18 
36 
29 
33 
60 
7 
30 
15 
27 
70 
4 
36 
5 
22 
75 
3 
34 
2 
20 
These results show practically complete protection for Nauru super- 
phosphate up to 75° C. but only 60° C. for Christmas Island. 
Standard tests were next carried out on Kosseir and Sofaga super- 
phosphates with varying added amounts of calcium carbonate at 70° C., the 
results being given in Table 8. 
