80  SUPERPHOSPHATE  OF  DECOMPOSED  BONES. 
stems  near  the  root,  and  cutting  through  the  pith,  when  the  sap 
exudes  in  a  day  or  two  and  hardens  in  the  opening,  after  which 
it  is  collected  by  the  peasants.  Its  price  there  was  about  3s.  2d. 
per  lb.  ;  23  tons  were  imported  in  1850  from  Smyrna,  and  the 
imports  have  since  annually  increased,  until  in  1853  they  reached 
nearly  70  tons. 
A  spurious  tragacanth  is  obtained  in  the  East  from  the  Ster- 
culia  urens  and  S.  foetida,  and  an  inferior  tragacanth  is  also 
procured  from  Cochlospermum  gossypium. — Journ.  Frank. 
Inst,  from  Journ.  Society  of  Arts,  London,  Nov.  1855. 
(To  be  continued.) 
i   .__  
ON  THE  SUPEKPHOSPHATE  OF  DECOMPOSED  BONES. 
By  W.  Wicke. 
Starting  from  the  supposition  that  the  acid  phosphate  of  lime 
in  the  bones  is  very  soon  converted  into  neutral  phosphate  in 
the  soil,  the  opinion  has  been  set  up  that'  the  superphosphate  only 
acts  by  its  fine  state  of  division.  It  has  even  been  recommended 
to  precipitate  again  the  acid  phosphate  of  lime  rendered  soluble 
by  sulphuric  acid  by  means  of  lime,  and  to  incorporate  this  with 
the  soil. 
As  far  as  I  am  aware,  no  experiments  have  been  made  upon 
the  behaviour  of  the  superphosphate  towards  the  ordinary  con- 
stituents of  the  soil,  which  may  have  a  neutralizing  action  upon 
it ;  I  mean  towards  carbonate  of  ammonia,  as  the  ordinary  pro- 
duct of  decomposition  of  the  organic  constituents  of  urine  and 
carbonate  of  lime.  Both  these  bodies  certainly  have  a  decom- 
posing action  upon  the  superphosphate,  but  not  of  such  a  nature 
as  to  separate  the  whole  of  the  phosphoric  acid  in  an  insoluble 
compound.  In  the  former  case  a  sufficient  quantity  of  phosphate 
of  ammonia  for  the  requirements  of  the  plants,  and  in  the  second 
an  acid  salt,  remains  in  solution. 
For  this  experiment  I  employed  very  pure  marl.  If  the  super- 
phosphate be  filtered  through  the  marl,  or  left  in  contact  with  it 
for  a  long  time,  a  portion  of  the  phosphoric  acid  is  certainly  com- 
bined with  evolution  of  carbonic  acid,  but  the  salt  is  not  entirely 
precipitated.  Even  in  this  case  we  present  immediately  to  the 
plant  a  phosphate  which  is  soluble  in  water. 
