^"^'iT.'xI^^'"^']  Contributions  from  the  School  of  Pharmacy,  etc.  459 
gave  an  abundant  precipitate  of  cuprous  oxide  (probably  due  to  sugar). 
Another  portion,  treated  with  ferric  chloride,  gave  a  purplish-black 
precipitate.  The  general  tests  for  alkaloids  gave  no  positive  results, 
but  the  quantity  of  material  was  not  large  enough  to  give  decisive 
results.  The  precipitate  of  resin  left  on  the  filter  was  well  washed  with 
water,  dried,  pulverized,  and  again  washed  and  dried. 
This  resin  had  the  appearance  of  powdered  cochineal.  The  residue 
left  by  evaporation  of  solutions  of  the  resin  looks  black.  Fragments 
under  the  microscope  show  the  reddish-brown  color,  the  resinous  lus- 
tre and  conchoidal  fracture.  From  the  100.00  grams  of  powdered 
bark,  7*93  grams  of  the  resin  were  obtained  :  equal  to  609  grains  from 
16  troyounces.  The  solubilities  of  the  resin  were  determined  at  first 
qualitatively,  and  then  quantitatively,  in  the  following  way  :  Saturated 
solutions  of  the  solvents  in  question  were  made  and  left  in  corked  test- 
tubes  over  night,  then  two  cubic  centimeters  of  the  clear  supernatant 
solution  were  taken  off  with  a  pipette  (filtration  being  objectionable  by 
reason  of  the  evaporation  of  the  menstruum)  and  evaporated  on  a  tared 
watch-glass  and  weighed.  The  volume  of  the  solution  was  multiplied 
by  specific  gravity  of  the  solvent  for  weight  of  the  solution :  not 
regarding  the  slight  increase  in  specific  gravity  caused  by  solution  of 
the  solid.  In  this  manner  it  was  ascertained  that  one  part  of  the  resin  is 
soluble  in 
14  parts  of  alcohol, 
15  "  chloroform, 
23        "  ether, 
122        "  benzole. 
It  is  soluble  in  aqueous  hydrate  of  ammonium,  potassium,  and  sodium  ; 
being  precipitated  from  these  solutions  by  acids. 
Treated  with  solution  of  potassium  hydrate,  the  resin  turns  green. 
This  test  is  best  obtained  by  evaporating  a  few  drops  of  the  solution  of 
the  resin  on  a  porcelain  surface,  to  obtain  a  thin  film,  and  adding  po- 
tassa  solution  of  ordinary  reagent  strength,  when  a  bright  red  color  is 
obtained.  On  addition  of  water  the  color  pales  to  a  sage  green.  Sul- 
phuric acid  dissolves  the  resin,  forming  a  reddish-brown  solution. 
A  percolate  of  the  powdered  bark  with  ether  of  U.  S.  P.  standard 
had  a  dark  reddish-brown  color,  and  left  a  brownish-black  residue. 
This  residue  was  treated  with  water  and  tested  for  tannic  acids  with 
negative  results.    Exhausted  with  hot  alcohol,  a  small  residue  was  left. 
