The Deterioration of Jute Materials. 
13 
damage as the temperature rises above 45 °C. and, in the vapour phase, 
above 60°C.; with hydrofluoric acid types excessive damage occurs in con- 
tact above 50°C., and, in the vapour phase, above 70°C. 
The presence of chloride in Egyptian phosphate rock (p. 5, footnote) 
presents a problem in the manufacture of superphosphate and there is need 
for an investigation into the nature of the chloride. If it occurs solely as 
the water soluble form, it may be possible to remove it by leaching before 
manufacture. 
(2) Control Measures. 
(i) Facilitation of Escape of Volatile Acid Vapours. 
Factory practice may be modified to facilitate the escape of volatile acid 
vapours, both in the mixer and in stacks. 
(ii) Neutralisation of Acids. 
Running tests should be made to determine the amount of alkaline sub- 
stances to be incorporated with the superphosphate to give maximum pro- 
tection, having regard to the nature of the superphosphate and temperature 
conditions. Such a treatment would result in some dilution of the super- 
phosphate and a reduction in the water soluble phosphoric oxide content. 
Experiments indicate, however, that the addition of ground limestone does 
not reduce the value of the phosphate in wheat growing. 
(iii) Spraying. 
Protection is afforded by the spraying of alkaline solutions on the upper 
surfaces of the topmost bags in the trucks immediately under the tarpaulins 
where optimum conditions for deterioration occur. 
(iv) Transport. 
Despatch of superphosphate manufactured from rock containing chlo- 
ride should be reduced to a minimum during the hottest months of the year. 
Delays in transport should be avoided. 
(v) Bulk Storage on Farms. 
Farmers should arrange to store the superphosphate in bulk as far as 
possible and a cement floor will be found convenient. After emptying, the 
bags should be well washed with water. A small amount of lime may be 
added to the washing water but strong suspensions of lime should be 
avoided. (P. 8, Table 4.) 
ACKNOWLEDGMENTS. 
The authors acknowledge the help and advice of the superphosphate 
manufacturers during this work and the assistance of colleagues in making 
many of the tests. 
By Authority : Robert H. Miller, Government Printer, Perth. 
