The  circumstance  that  not  only  Lehmann,  but  all  other  chemists,  have
found  such  a  small  amount  of  copper  in  vegetable  substances  must  be
ascribed  to  the  same  or  to  a  similar  source  of  error. — Pharm.  Journ.,  Aug.
29,  177  ;  from  Chem.  Ztg.,  1896,  584.
6 14  REPORT  ON  THE  PROGRESS  OF  PHARMACY.
LEAD,

Lead  Peroxide — Improved  Method  of  Manufacture. — H.  N.  Warren
observes  that  lead  peroxide  is  now  largely  consumed  in  some  commercial
quarters,  in  consequence  of  which  various  methods  have  been  devised  for
its  preparation.  He  calls  attention  to  the  difficulties  encountered  in  carry-
ing out  these  processes,  and  recommends  the  following  synthetical  method
as  giving  a  pure  and  theoretical  yield,  free  from  secondary  products :  In
order  to  bring  about  the  reaction,  either  litharge  or  sulphate  of  lead  from
vitriol  tanks,  etc.,  is  introduced  into  canvas  bags,  through  which  is  inserted
a  lead  sheet.  These  bags  are  now  immersed  in  dilute  vitriol,  and  con-
nected respectively  to  sheets  of  iron ;  the  sulphate  or  other  plumbic  com-
pound contained  therein  is  thus  speedily  and  completely  reduced  to  the
spongy  metal,  the  bags  being  afterwards  connected  alternately  by  their
lead  plates  and  exposed  to  an  electric  current,  the  positives  being  thus
completely  converted  into  peroxide,  whilst  the  temporary  accumulator
thus  produced  is  again  emptied  of  its  current  into  further  quantities  of
spongy  metal,  thus  manufacturing  a  further  quantity  of  peroxide.  The
process  thus  set  forth,  when  rightly  conducted,  yields  an  absolutely  pure
oxide,  on  a  cheaper  scale  than  those  hitherto  recommended. — Chem.
News,  Sept.  i8,  1896,  144.
Metaplumbates — Formation  and  Characters, — Several  years  ago  M.
