Am.  Jour.  Pharm.  \ 
March,  19 18.  > 
Current  Literature. 
215 
centration  of  I  in  12,500,  quantitative  observations  can  only  be 
made  at  concentrations  between  1  in  1,500  and  1  in  5,500.  The 
method  is  rendered  more  sensitive  if  1  Cc.  of  10  per  cent,  aqueous 
ammonia  is  added  about  five  minutes  after  the  addition  of  the 
iodic  acid.  Morphine  can  thus  be  detected  at  a  concentration  of  1 
in  18,500  and  estimated  at  concentrations  between  1  in  5,000  and 
1  in  16,500. 
II.  Estimation  with  Marquis's  Reagent. — One  Cc.  of  the 
morphine  solutions  prepared  as  above  is  evaporated  in  a  small  basin, 
the  residue  is  treated  with  1  Cc.  of  Marquis's  reagent  (2-3  drops  of 
40  per  cent,  formaldehyde  solution,  3  Cc.  of  cone,  sulphuric  acid), 
and  the  violet  solution  is  washed  into  the  comparison  tube  with  4 
Cc.  of  sulphuric  acid.  The  colors  are  examined  by  transmitted  light, 
since  in  reflected  light  an  actual  color  change  from  blue  to  bluish- 
brown  renders  the  comparison  untrustworthy.  Morphine  can  thus 
be  estimated  at  concentrations  between  1  in  1,400  and  1  in  14,000, 
and,  the  dilution  with  the  sulphuric  acid  being  omitted,  can  be  de- 
tected at  a  concentration  of  1  in  25,000. 
Two  samples  of  ripe  poppy  capsules  examined  by  these  methods 
were  found  to  contain  0.017  and  0.068  per  cent,  of  morphine  re- 
spectively; in  neither  case  did  the  seeds  contain  morphine.  (From 
the  Journal  of  The  Society  of  Chemical  Industry.) 
Determination  of  Shells  in  Cocoa. — A  method  for  the  detec- 
tion of  shells  in  cocoa  is  described  by  Wasicky  and  Wimmer  (N. 
Nahr  Genussm.,  30,  25-7,  1915).  Thi9  method  is  based  upon  the 
difference  in  appearance  between  shell  and  nib  tissue  when  viewed 
through  a  microscope  by  ultra-violet  light.  The  proper  light  is 
best  obtained  by  means  of  a  carbon-iron  arc  lamp,  the  light  before 
reaching  the  mount  being  passed  through  a  Wood-Lehman  filter 
(two  blue  Uviol  glass  cells,  one  filled  with  1 : 2,000  nitrosodimethyl- 
analine,  and  the  other  with  concentrated  copper  sulphate  solution. 
The  color  of  the  shell  tissues  when  seen  by  this  light  is  buff  or 
brown,  the  mucilage  cells  being  almost  colorless  or  a  light  yellowish 
green.  The  nib  tissues  appear  in  various  shades  of  blue-violet.  The 
details  of  the  method  are  as  follows :  Treat  ten  milligrams  of  the 
powder  with  ten  cubic  centimeters  of  alcohol-glycerol  mixture 
(equal  parts  of  each)  and  allow  to  stand  for  one  hour.  Centri- 
fuge, pour  off  the  liquid  layer  and  add  one  cubic  centimeter  of 
