20 BULLETIN 312, U. S. DEPARTMENT OF AGRICULTURE. 
MECHANICAL TREATMENT OF PHOSPHATES. 
The patents listed in Table XI, Appendix, deal with the mechan- 
ical treatment of either raw phosphates or the chemically treated 
product. The first seven processes are primarily intended for the 
treatment of bones or phosphates to be used in the manufacture of 
baking powder. The other processes listed hardly require any more 
detailed descriptions than those given in the tables. AI the patents 
covering these processes have long since expired, and they can there- 
fore be used without payment of royalties. 
MISCELLANEOUS PROCESSES FOR THE PRODUCTION OF AVAILABLE 
PHOSPHATES. 
Under the head of miscellaneous are included all the processes 
which can not very well be separately listed. Many of these processes 
are on their face practically valueless, while others have features 
which make it appear they might be successfully employed in the 
production of fertilizers of some value. A list of the patents under 
this head is given in Table XII, Appendix. 
The process in the above table which has probably attracted the 
most attention is that of Coates,t in which the inventor claims to 
produce available phosphoric acid and potash from minerals con- 
taining these elements by the action of bacteria, which attack and 
break down the rocks. His process consists in first obtaining a culture _ 
by adding breaking-down or decaying rock to a sterilized culture 
medium. He then inoculates sterilized phosphate rock or feldspar 
with the culture thus prepared, with the result that the bacteria 
attack the rock minerals, rendermg the phosphoric acid and potash 
contained therein soluble in the soil solution. 
It is understood that field experiments are being conducted to test 
the fertilizer value of rock treated in this way, but the results of 
these experiments have not yet been reported. 
1 United States Patent No. 947795 (1910). 
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