The Deterioration of Jute Materials. 
5 
early in the season and apparently suffered hot weather in the trucks. The 
remaining eight bags were normally sound for superphosphate bags.* 
(ii) Laboratory Tests to Determine the Action of Superphosphates from 
Rocks of Different Sources on Jute Materials. 
In this section of the investigation two series of tests were made. 
In the first series, standard strips of sacking were placed in stoppered 
bottles containing superphosphate. Some strips were in contact with the 
superphosphate; others were suspended in the vapour phase above it. The 
bottles were exposed to the weather on a roof for a number of days before 
the determination of the tensile strength. These tests were carried out 
during two periods, January 22nd to 28th and February 3rd to 13th, 1942. 
The first period was the hotter, the maximum solar radiation temperature 
being 70 °C. and the average 63 °C., compared with 64° C. and 60° C. for 
the second period. 
The results of the first test are given in Table 1, and from them the 
following principles emerge: 
(a) There appears to be no relationship between the amount of the 
excess acidity and the damage to the fabric. 
(b) Superphosphate containing chloridef but little or no hydro- 
fluoric acid, as shown by freedom from etching in the glass 
containers, caused most severe damage. 
TABLE ]. 
Superphosphate. 
Excess 
Acidity. 
(% H 2 S0 4 ) 
Water 
Soluble 
Chloride 
as % HC1 
Tensile 
Strength. 
lbs. 
A. — Superphosphates causing moderate to severe etching. 
Nauru I. 
0-6 
nil 
Christmas 
1*6 
nil 
Nauru I. plus 0-5% HF 
nil 
Nauru I. plus 0*7% H 2 SOj 
... 
nil 
Kosseir I. 
B. — Superphosphate causing little or no etching hut containing chloride. 
0-9 
•16 
39 
« 
In the second series of tests, five-ply jute twine was substituted for the 
strips. Eight-inch lengths of twine were used in 2-ounce bottles containing 
20 grams of superphosphate. At least six pieces of twine were used for 
each test and all treatments were carried out in an electric oven at the 
required temperatures for a period of three days and four nights. 
* Tests carried out at the same time on bags containing Potato Manure E (of which 
potassium chloride is a constituent) despatched in hot weather, showed very serious 
damage. 
t Egyptian phosphate rock is mined at a depth of about 1,000ft. and occurs as a 
layer below ground water level. The rock contains a small amount of water soluble 
chloride. One sample analysed by Mr. Walker, of Cresco Fertilisers LtcC., contained 0 36% 
water soluble chloride, equivalent to 0.59% sodium chloride. Another, representing 
another shipment, contained water soluble chloride equivalent to 0.64% sodium chloride 
The ground water is probably somewhat saline and the deposit of salt is left on the rock 
when dried prior to, shipment. 
