ON  THE  ADULTERATION  OF  TIN  FOIL. 
257 
in  the  different  varieties  of  resin  of  benzoin.  It  is  this  fact  that 
has  led  the  authors  to  believe  that  they  have  found  it  in  a  state  dif- 
ferent from  simple  mixture.*  The  combination  is  never  intimate 
because  it  can  be  undone  not  only  by  fractional  precipitation, 
but  by  simple  crystallization. 
Finally,  the  fusing  point  of  this  acid  is  26°  C.  below  that  of 
benzoic  acid  (120°  C),  and  M.  Aschoffhas  found  that  a  little 
cinnamic  acid  will  modify  greatly  the  fusing  force  of  the  ben- 
zoic. 
The  complete  separation  of  these  acids  has  been  effected  by 
way  of  fractional  precipitation,  by  means  of  nitrate  of  silver 
acting  on  the  ammoniacal  salt. 
M.  Aschoffhas  since  found  cinnamic  acid  exclusively  present  in 
the  almonds-like  tears  of  a  benzoin  of  Sumatra,  which  had  a  strong 
odor  of  storax.  These  almonds  were  in  greater  part  soluble  in 
ether,  the  solution  contained  cinnamic  acid  11  per  cent ;  resin 
soluble  in  alcohol  78  per  cent ;  foreign  matter  4-5  per  cent.  At 
the  most  there  was  but  5.4  per  cent  of  resin  insoluble  in  ether 
and  3olublein  alcohol — Annal.  der  Chem.  andJourn.  de  Pharm. 
Nov.,  1861. 
ON  THE  ADULTERATION  OF  TIN  FOIL. 
By  Mr.  J.  H.  Baldock. 
Having  occasion  a  short  time  back  to  prepare  some  com- 
pounds of  tin,  I  employed  for  the  purpose,  in  the  absence  of 
granulated  metal,  some  tin  foil,  and  was  surprised  to  find  my 
product  very  largely  contaminated  with  some  other  metal.  Upon 
careful  examination  of  the  tin  foil  which  I  had  used,  I  found  it 
*  (Note  by  M.  J.  Nickles.) — Benzoic  and  cinnamic  acids  belong  to  the 
same  homologous  series  of  aromatic  acids  ;  in  view  of  their  composition  they 
are  related  as  the  acetic  and  butyric  acids. 
Acetic  acid  C4  H4  O4 
Butyric  C8  H8  04 
Benzoic  ^14^6  ^4 
Cinnamic  C18H8  04 
As  has  been  shown  in  this  Journal  (Jour,  de  Pharm.  xxxiii.  p.  351) 
how  the  two  first  can  combine  to  form  butyro-acetic  acid,  CeHeO*,  so 
benzo-cinnamic  acid  of  MM.  Kolbe  &  Lauteman  is  a  combination  of 
the  same  kind,  and  not  more  stable  than  the  first. 
17 
