The Deterioration of Jute Materials. 
3 
(ii) Those manufactured from Egyptian f rock phosphates containing 
appreciable quantities of hydrochloric but little, if any, hydrofluoric acid. 
Expressed as HC1, the chloride content of the first group is from 
0 01 to 0-02% and, in the second group, 0 09% for Sofaga and 0-16% 
for Kosseir. 
The use of Christmas Island and Egyptian rock phosphates in place of 
those from Nauru and Ocean Island brought about a change in manufacturing 
processes. For the production of the required percentage of water soluble 
phosphate, Christmas Island rock required from 5 to 10% more acid than 
the Nauru and Ocean Island Rock. The Egyptian ma ; erial was readily 
attacked by the acid. As the Egyptian phosphate was of lower grade than 
the Christmas Island, the commercial superphosphates were made by mixing 
the two types in appropriate proportions to obtain a mixture containing 22% 
total phosphoric oxide, with 20* *25% being water soluble. The new super- 
phosphate gave a free acidity (as H.,S0 4 ), generally of from 1-4 to 1-6% 
as compared with 0*8 per cent, to 1*0 per cent, for Nauru and Ocean Island 
superphosphates. 
Certain manufacturers arranged to neutralise part of this excess acidity 
by the incorporation of small amounts of finely ground limestone and it was 
found that the practice was sufficiently satisfactory for it to be adopted as 
a routine measure. The spraying with soda ash solution of the upper sides 
of the topmost bags in the trucks, where contact with the railway tarpaulins 
would be made, was found to afford further protection. 
(2) Factors Likely to Cause Deterioration of Jute Materials. 
The deterioration of jute materials under varying conditions was in- 
vestigated. Materials were studied, firstly in stacks designed to simulate 
actual railing conditions and, secondly, under laboratory conditions. 
The materials were tested under standard conditions with apparatus 
kindly lent by Messrs. Cuming Smith and Mt. Lyell Farmers’ Fertilisers 
Limited.* Measurements were made of the tensile strength of the jute 
material. At first, tests were made with strips of jute sacking exactly 
one inch in width and cut across the bag so that the strength of the shot 
fibres was determined. As this method proved cumbersome and slow, later 
tests were made with five-ply jute twine of the type commonly used for 
sewing bags.t 
Tests were first of all carried out with new jute materials and there 
was found to be a very substantial variability in the tensile strength of 
untreated fabric and twine. With strips of material the tensile strength 
varied from 125 to 197 lbs. for strips one inch in width. The majority of 
the tests were in the neighbourhood of 140 lbs. and this figure is adopted 
as the normal tensile strength of a jute strip one inch in width. With five- 
ply jute twine the range was from 25 to 52 lbs. and the normal tensile 
strength is taken as 36 lbs. 
t The Egyptian rock phosphates were shipped from two Red Sea ports, Kosseir and 
Sofaga. Shipments were kept separate in the investigation but nothing is known regard- 
ing the source of the material represented by each shipment. 
* The laboratory tests on jute materials and tensile strength determinations were made 
in the Department of Agriculture laboratories. The chemical determinations were made 
in the Government Chemical Laboratory. 
+ Collateral tests on railway tarpaulins and similar fabrics were made by Dr. C. R. 
Kent at the Railway Laboratory, Midland Junction. 
