Am^Xi87trm'}    Paints,  Colors  and  their  Analysis.  159 
No  water  nor  benzin.    (Test  for  water — anhydrous  cupric  sulphate.) 
The  fact  that  this  paint  began  to  boil  at  250°F.,  when  also  distilla- 
tion began,  excludes  the  probability  of  the  presence  of  the  volatile 
petroleum-benzin.  A  separation  of  oil  of  turpentine  from  the  above- 
named  hydrocarbon  by  fractional  distillation  is  impossible.  The  oil 
and  resinous  constituents  began  to  decompose  at  3500  to  400°F.  on 
formation  of  acrolein. 
The  white  pigments,  of  which  said  paint  contained  34*405  per  cent., 
analyzed  as  follows  : 
Oxide  of  zinc,  .  .  .  .  .  66-400  per  cent. 
Lime,        .  .  .  .  i'758 
Sulphuric  acid,  ....      1  920 
Clay,        ...  14  per  cent.  sol.  30  300 
100-378 
besides  traces  of  lead  and  iron. 
Probable  working  formula,  70  "zinc"  +  30  alum-clay. 
The  tests  for  magnesia,  borax,  water  and  carbonic  acid  gave  negative 
results.  It  is  evident  that  in  liquid  paints  a  "cheap"  vehicle  will  per- 
mit their  sale  at  a  low  price  or  help  to  increase  the  profits  already  pro- 
duced by  a  strongly  adulterated  colorific  base  ;  it  is  also  in  these  very 
paints — -not  without  some  exceptions,  however-— where  the  u  humbug  " 
reaches  its  highest  point  of  culmination. 
Lake  Colors.— I  may  be  allowed  to  insert  here  a  few  remarks  on 
lake  colors.  The  numerous  pigments  of  vegetable  and  animal  origin 
show,  to  a  certain  extent,  a  great  deal  of  similarity  among  each  other, 
as  most  of  them  form  insoluble  colored  compounds  with  alumina, 
wiiich  are  generally  termed  lakes,  and  whereby  the  coloring  principles 
of  dye-woods  are  transferred  into  insoluble  colored  compounds,  which 
find  frequent  application  in  paper-staining,  calico-printing  and  various 
other  industries.  Stannous  chloride  also  forms  lakes  with  a  large  num- 
ber of  pigments  ;  it  is,  however,  more  expensive  than  the  alum  solu- 
tions required  in  the  former  process.  One  of  the  most  beautiful  lakes 
is  undoubtedly  carmine,  an  insoluble  compound  of  the  pigment  con- 
tained in  cochineal.  There  are  quite  a  number  of  brands  in  the  mar- 
ket, of  which  Carmine  No.  40  is  the  finest.  While  the  lower  grades 
contain  alumina,  this  latter  one  is  free  from  it,  and  perfectly  soluble  in 
ammonia.  From  its  mode  of  manufacture,  which  may  be  fairly  termed 
a  public  secret,  as  well  as  from  the  fact  that  it  leaves  but  very  little 
non-aluminous  ash,  it  may  be  considered  an  insoluble  combination  of 
