262 
ON  A  NEW  VARIETY  OF  COCHINEAL. 
designated  as  vegetable  albumen ;  it  does  not  coagulate  until 
after  long  boiling,  and  remains  in  great  part  in  a  soluble  state  in 
tubers  which  have  been  boiled  or  dried,  even  at  a  tolerably  high 
temperature.  Thus,  the  Chinese  potato,  when  cut  into  thin  slices 
and  dried  on  a  stove,  furnishes  a  product  which  may  be  reduced 
to  powder,  and  which  when  treated  with  water  forms  a  paste  re- 
sembling in  its  plasticity  that  produced  by  wheat-flour. — Cketn. 
Gaz.,  Feb.  15,  1855,  from  Oomptes  Bendus,  Jan.  15,  1855,  p. 
128. 
ON  A  NEW  VARIETY  OF  COCHINEAL— CAKE  COCHINEAL. 
(Obtained  from  Cordova,  the  Argentine  Republic,  South  America.') 
By  James  Stark,  M.D.,  F.R.S.E. 
My  brother-in-law,  Mr.  Charles  Bertram  Black,  when  lately  on 
a  visit  to  some  parts  of  the  Argentine  Republic,  South  America, 
had  his  attention  directed  to  a  dye  stuff,  or  coloring  matter,  which 
the  natives  of  Cordova  consider  of  great  value,  and  employ  for 
dj^eing  cloths  of  all  shades  of  red.  Imagining  that  the  sub- 
stance was  unknown  here,  and  that  it  might  be  profitably  im- 
ported for  use  in  the  Arts,  Mr.  Black  procured  a  small  quantity 
of  it,  and  sent  it  to  James  Richardson,  Esq.,  of  this  city.  The 
whole  information  given  regarding  it  is  contained  in  a  letter 
addressed  to  me,  and  dated  "  Santiago,  April,  1854."  After 
stating  that  the  cake  sent  is  a  substance  used  for  dyeing  cloth 
all  kinds  of  red,  he  says,  "It  is  the  gum  which  exudes  from  a 
species  of  cactus  like  the  prickly  pear.  If  Mr.  Richardson 
thinks  he  can  make  an  advantageous  article  of  commerce  of  it, 
I  can  make  all  the  necessary  arrangements  for  him  with  a  col- 
lector. The  dye  costs  from  4df.  to  9d.  the  ounce,  according  to 
the  vicinity  to  the  place  where  it  is  found." 
The  dye  stuff,  as  sent  home,  is  a  solid  flat  cake,  about  a  quarter 
of  an  inch  thick,  of  a  deep  red  color,  and  is  marked  on  its  sur- 
face as  if  it  had  been  subjected  to  pressure  between  folds  of 
coarse  linen.  The  cake  broke  with  a  jagged  fracture,  and  over 
the  surface  were  seen  -occasional  whitish  spots,  resembling  im- 
bedded fragments  of  the  silver  variety  of  the  cochineal  insect. 
A  few  of  the  strong  thorny  prickles  of  the  cactus  opuntia,  or 
some  similar  species,  were  also  seen  projecting  from  the  broken 
edges. 
