THE  AMERICAN 
JOURNAL  OF  PHARMACY. 
APRIL,  1878. 
PAINTS,  COLORS  AND  THEIR  ANALYSIS. 
By  Henry  G.  Debrunner,  Chemist. 
As  it  is  quite  customary  in  many  parts  of  the  United  States  that 
druggists  are  at  the  same  time  dealers  in  paints,  colors,  window  glass, 
putty,  etc.,  a  closer  examination  of  these  articles,  as  to  their  composi- 
tion, character  and  most  frequent  adulterations,  will  probably  be  of 
some  interest  to  the  readers  of  this  journal. 
White  Paints. — In  speaking  of  white  lead,  the  following  classifica- 
tion will  be  most  suitable  : 
1.  Pure  white  lead,  a  mixture  of  plumbic  carbonate  and  oxy hydrate. 
2.  White  paints,  bearing  the  above  name  and  containing  a  certain 
percentage  of  real  white  lead,  which  very  often  decreases  to  mere  traces. 
3.  White  paints,  not  unfrequently  marked  "  pure  white  lead,"  but 
without  the  name  of  the  manufacturing  firm,  and  containing  no  lead 
whatever. 
The  following  analysis  of  a  sample  of  white  lead,  prepared  by  the 
Dutch  method  and  exhibited  at  the  Centennial  Exposition  in  Philadel- 
phia, may  be  taken  as  a  representative  of  the  first-class,  the  approximate 
formula  derived  from  the  analysis  being  Pb50C29H86O151. 
Plumbic  oxide,  .  .        83*9668  per  cent. 
Carbonic  acid,      .  .  .  9-6000 
Water  combined,  .  .  .  5*8332. 
Moisture,  .  .  .  o*6ooo 
There  are  chiefly  two  methods  in  use  for  the  manufacture  of  white 
lead,  viz.  :  the  Dutch  and  the  French  process.  The  former  consists  in 
a  slow  corrosion  of  plates  or  buckles  of  metallic  lead  in  pots  contain- 
ing a  small  quantity  of  dilute  acetic  acid  ;  the  basic  acetate  thus  formed 
is  changed  into  the  corresponding  carbonate  by  the  action  of  the  car- 
bonic acid  of  the  atmosphere,  "which  requires  several  weeks'  time.  The 
French  process  consists  in  forming  a  basic  acetate  by  saturating  acetic 
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