204 
NOTES  ON  BENZOIC  ACID  AND  SOME  BENZOATES. 
4th.  Wash  well  with  hot  water  till  the  washing  liquid  is  perfect- 
ly clear. 
5th.  Press  the  alloy  in  a  deer-skin  till  all  the  excess  of 
mercury  is  out,  and  expose  to  the  air.  In  less  than  hour  it 
becomes  very  hard. 
A  singular  property  I  must  notice,  is  the  action  of  zinc 
on  this  alloy ;  if  the  mercury  contains  a  little  zinc,  the  alloy 
comes  very  hard,  but  it  breaks  in  pieces  by  the  least  knock. 
Here  is  the  analysis  of  it : 
Analysis  in  the  ordinary  state. 
Copper,  25.75  25.81 
Mercury,  74.25  74.19 
100.00  100.00 
Density  11.48. 
Analysis  when  soft. 
Copper,  25.43 
Mercury,  74.57 
100.00 
Density,  11.033. 
Analysis  after  it  has  been  soft  and  hard  again. 
Copper,  25.48 
Mercury,  74.52 
100.00 
Density,  11.036. 
Such  is  the  composition  of  this  alloy,  which  is  given  for  a  new 
discovery,  and  which  was  described  seven  or  eight  years 
ago,  and  was  called  alloy  of  the  dentists. 
NOTES  ON  BENZOIC  ACID  AND  SOME  BENZOATES. 
Br  John  M.  Maisch. 
Benzoic  Acid. — When  benzoin  is  treated  for  benzoic  acid  by 
Mohr's  process,  it  is  necessary  to  gradually  increase  the  heat, 
