Am.  Jour.  Pharm.  > 
Feb.,  1884.  J 
Action  of  Acids  on  Lead  and  Tin. 
117 
The  lead  gave  dense  black  precipitates,  finer  in  the  tartaric  and  cit- 
ric acids  than  in  the  acetic.  The  tin  came  down  brown  in  acetic,  and 
yellow  and  flocculent  in  the  tartaric  and  citric  acids.  With  the  alloys, 
the  precipitates  were  dark-brown  in  acetic  and  light-colored  and 
flocculent  in  the  other  acids.   The  results  are  given  in  the  above  table. 
Some  similar  experiments  were  now  conducted  in  stoppered  bottles. 
In  order  to  exclude  air  as  much  as  possible,  the  bottles  were  heated, 
filled  with  acid  while  hot ;  boiled ;  and  at  once  tightly  stoppered. 
The  results  are  given  in  the  last  line  of  the  above  table.  Another 
series  of  experiments  proved  conclusively  that  galvanic  action  did 
not  influence  the  rapidity  of  the  corrosion,  the  action  generally  being 
slight  at  first,  and  increasing  as  time  went  on.  Dilute  acids,  if  in 
sufficient  quantities,  cause  more  corrosion  than  stronger  ones.  Some 
experiments  were  next  tried  on  the  tins  themselves.  200  cc.  of  the 
acids  were  put  into  three  empty  tins,  tied  over  with  paper,  and  exam- 
ined after  two  weeks.  The  citric  and  tartaric  acids  had  removed  the 
tinning.  A  white  powder  was  deposited  in  the  citric  acid  solution 
soluble  in  hydrochloric  acid.  The  quantities  of  lead  and  tin  dissolved 
were  as  follows  : 
In  addition  to  these  metals,  there  was  a  good  deal  of  iron  dissolved. 
The  lead  was  derived  from  the  solder. 
The  result  of  the  analysis  of  various  samples  of  tin  plate  showed 
that  the  superior  class  or  "  Bright  plate  "  was  tinned  with  pure  tin, 
and  that  this  quality  is  the  one  almost  universally  used  for  tinware; 
the  inferior  class,  or  "Terne  plate,"  as  is  understood,  contains  lead 
to  the  extent  of  70  per  cent. ;  it  is  considerably  duller  than  bright 
plate,  and  is  used  almost  exclusively  for  roofing  purposes.  The  analy- 
sis of  commercial  tin  foil  proves  it  to  be  of  a  very  mixed  character, 
from  pure  tin  to  stuff  containing  90  per  cent,  of  lead ;  the  latter 
would  prove  deleterious  if  used  for  cheese  or  like  substances. — Jour, 
Chem.  Soc,  Nov.  1883,  p.  1038 ;  Chan.  News,  xlvii,  290,  300. 
Grams  dissolved  by 
Metals. 
Lead.. 
Tin  
Acetic  acid.    Tartaric  acid.   Citric  acid. 
 0-0117         0-0873  0-1559 
....0-4178         1-0430         0  6828 
