22 
BULLETIN 144, U. S. DEPARTMENT OF AGRICULTURE. 
It is not stated whether the acid phosphate was made by the ' ■ open- 
dump" or "den" method, but an inspection of the table will show 
that little change has taken place in the material after keeping several 
months. In Table VI are given the analyses of two piles of acid 
phosphate sampled after standing certain definite periods of time. 
The acid phosphate in both cases was made by the " open-dump" 
system. 
Table VI.- — Analyses of acid phosphate from two piles after standing for certain periods. 
Time of storage. 
Available 
Insoluble 
phos- 
phos- 
phoric 
phoric 
acid. 
acid. 
Per cent. 
Per cent. 
15.70 
2.05 
16.63 
1.02 
16.93 
.47 
15.55 
1.50 
15.70 
1.80 
17.19 
.18 
Moisture. 
No. 1: 
3 days... 
10 days . . 
6 months 
No. 2: 
13 hours . 
3 days . . . 
6 months 
Per cent. 
12.80 
12.70 
13.80 
12.60 
13.94 
Although the percentage of available phosphoric acid continued to 
increase after storing the material for several months, this increased 
availability was largely offset by a corresponding rise in the moisture 
content of the product. 
DISINTEGRATING THE ACID PHOSPHATE'. 
Before acid phosphate can be bagged and shipped it must be broken 
up and put through coarse sieves. In the case of superphosphate 
which has been carefully made it often suffices to throw the material 
by means of shovels upon inclined screens, the force of the impact 
being great enough to disintegrate the lumps. When dealing, with 
acid phosphate, however, which has been improperly made or stored 
for a long time, it is often necessary to use a machine for breaking up 
the material. The ordinary crushing devices do not "answer for this 
purpose, owing to the tendency of the acid phosphate to pack or be- 
come sticky when pressure is applied, so disintegrators of a special 
type must be employed. 
In a machine like that shown in Plate V, figures 1 and 2, complete 
pulverization is brought about by submitting the material to innu- 
merable shocks, but in such manner that no opportunity is given the 
acid phosphate to pack or gum together. 
The disintegrator consists of a number of concentric cages made up 
of steel bars, all of which are inclosed in a casing. The cages are 
usually four in number, the first and third attached to a shaft which 
revolves in one direction and the second and fourth attached to 
