160  Paints,  Colors  and  their  Analysis.     { AmA&x87h8arm' 
carminic  acid,  C17H18O10,  with  animal  matter,  it  being  precipitated  by  isin- 
glass from  an  acid  aqueous  decoction  of  cochineal,  containing  potassic 
bitartrate,  alum  and  an  excess  of  citric  acid.  The  mother-liquor  of 
this  first  precipitate,  which  is  termed  "  black  liquor"  by  the  practical 
men,  very  probably  on  account  of  its  beautiful  u  red "  color,  will 
yield  a  second  precipitate  of  carmine-red,  CuH1207,  on  standing  for 
some  time.  The  red  pigments  of  the  "  black  liquor  "  are  almost  per- 
fectly precipitated  by  alumina  in  statu  nascendi.  Stannous  chloride  and 
mercury  nitrate  also  produce  scarlet  precipitates,  which,  however,  are 
of  mere  scientific  interest. 
Anilin  and  phenol  colors  in  many  instances  show  a  similar  affinity  to 
alumina  and  stannous  oxide ;  the  only  drawback  to  a  general  applica- 
tion of  these  beautiful  pigments  in  form  of  lakes  is  their  rapid  fading. 
Quite  fiery  shades  can  also  be  prepared  by  merely  immersing  starchy 
flour  or  whitening  in  a  solution  of  these  pigments.  In  the  French 
department  of  the  Philadelphia  Exposition  a  number  of  such  lakes 
were  exhibited,  the  base  of  which  was  said  to  be  starch.  The  quality 
of  these  colors  can  be  considerably  improved  by  the  addition  of  certain 
animal  substances,  as,  for  instance,  albumen,  casein,  isinglass  or 
white  glue,  for  which  these  artificial  pigments  show  a  great  affinity, 
thus  effecting  a  more  intimate  union  between  base  and  pigment.  This 
process  possesses  some  similarity  with  the  tl  animalization  of  cotton," 
in  dyeing,  which  consists  in  impregnating  the  vegetable  cotton  fibre 
with  animal  matter,  in  order  to  facilitate  the  fixation  of  the  dye.  For 
corallin  lakes  I  can  recommend  the  following  process  from  my  own 
experience  : 
Two  liters  of  corallin  solution,  containing  250  grams  of  corallin^ 
rendered  soluble  by  one  pound  of  sal  soda,  are  equivalently  precipitated 
by  one  liter  of  calcic  chloride,  containing  200  grams  CaCl2.  Corallin,. 
the  product  of  the  action  of  nascent  carbonic  oxide  on  phenol,  being 
soluble  in  alkaline  carbonates,  becomes  deprived  of  its  solvent  on  addi- 
tion of  calcic  chloride,  and  will  precipitate  together  with  calcic  car- 
bonate in  a  state  of  very  fine  division.  This  precipitate  may  be  mixed 
with  starch  or  flour  to  produce  lighter  shades  of  scarlet.  If  a  solution 
of  isinglass  has  been  added,  on  precipitation  a  small  quantity  of  alum  is 
added.  The  lake  thus  obtained,  which  is  of  a  beautiful  scarlet  shade> 
is  dried  at  about  I50°F.  It  fades  less  readily  than  if  prepared  without 
addition  of  isinglass,  which  seems  to  prevent,  at  least  to  some  extent, 
the  formation  of  the  light  rose-colored  calcic  rosolate. 
Black  Diamond  Steel  Works,  March  12,  1878. 
