AmjuSST"m'}  S°me  Commercial  Cocoas.  321 
ing  and  bringing  the  measure  up  to  100  c.c.,  50C.C.  were  made  alka- 
line with  sodium  hydrate  solution,  filtered,  50  c.c.  of  Fehling's  solu- 
tion added,  and  the  liquid  kept  at  a  temperature  of  900  C.  for  half 
an  hour,  then  filtered  and  the  precipitate  well  washed  with  hot 
water,  dried,  ignited  and  the  percentage  of  starch  calculated  from 
the  cupric  oxide  so  obtained. 
Another  portion  of  the  powder,  after  treatment  with  ether  to 
remove  fat,  was  examined  microscopically  for  the  detection  of 
foreign  starches.  The  results  were  mostly  negative  as  only  one,  No. 
1 1  contained  more  of  a  foreign  starch  than  would  be  allowable  by 
accident.  In  No.  4  the  character  of  the  starch  was  somewhat 
changed  by  fermentation,  and  in  No  7  the  granules  were  consider- 
ably disintegrated,  due  probably  to  excessive  heating.  No.  2  con- 
tained a  rather  large  amount  of  starch,  but  it  seemed  to  be  that  of 
genuine  cocoa. 
The  nutritive  value  that  the  cocoas  are  supposed  to  possess  sug- 
gested the  importance  of  a  nitrogen  determination  that  an  idea  of 
the  quantity  of  albumenoids  present  might  be  had.  To  accomplish 
this,  Kjeldahl's  process  was  essentially  carried  out  as  follows  :  About 
I  gramme  of  the  powder  was  placed  in  a  500  c.c.  flask  with  approxi- 
mately 700  mg.  of  freshly  precipitated  and  thoroughly  washed  mer- 
curic oxide,  50  c.c.  of  sulphuric  acid  were  added,  the  flask  contain- 
ing the  mixture  placed  on  a  sand-bath,  the  heat  regulated  until 
frothing  ceased,  and  the  mixture  raised  to  the  boiling  point  until  the 
liquid  was  clear  and  of  a  light  straw  color.  To  this  liquid,  while 
warm,  potassium  permanganate  was  gradually  added  until  a  perma- 
nent purple  color  was  imparted.  The  addition  of  the  potassium 
permanganate  required  considerable  care,  and  it  was  necessary  to  add 
small  quantities  of  water  from  time  to  time  to  keep  the  contents  of 
the  flask  in  a  liquid  condition.  25  ex.  of  a  solution  of  potassium 
sulphide  (40  grammes  in  1,000  c.c.  of  distilled  water)  were  then 
added,  and  to  this  50  c.c.  of  a  saturated  solution  of  potassium 
hydrate,  or  enough  to  render  the  liquid  alkaline,  and  lastly,  a  few 
pieces  of  granulated  zinc.  This  mixture  was  then  distilled  by  means 
of  a  Liebig  condenser  into  50  c.c.  of  decinormal  volumetric  solution 
of  oxalic  acid,  and  the  excess  of  acid  neutralized  by  decinormal 
volumetric  potassium  hydrate  solution.  The  albumenoids  were 
calculated  from  these  figures  after  having  deducted  the  percentage 
of  nitrogen  found  to  exist  as  theobromine. 
