4H  Artificial  and  Natural  Digestions.  {Am'l™x/^xm~ 
the  least  quantity  of  cold  water;  press  the  filter  with  the  mor- 
phine, between  blotting  paper ;  dry  at  ioo°  C.  to  constant  weight ;, 
weigh  between  watch  crystals  and  calculate  the  result  to  percentage. 
The  assay  will  consume  only  one  day's  time. 
Solid  extracts  will  have  to  be  dissolved  in  water  and  treated  as 
above.  I  take  two  grams,  dissolve  in  50  cc,  water  and  obtain  the 
most  satisfactory  results  with  1  (one)  cc.  ammonia. 
I  am  of  the  opinion  that  a  dilute  fluid  and  the  least  possible 
quantity  of  ammonia  is  to  be  preferred  to  a  concentrated  fluid  and 
an  excess  of  ammonia  as  used  in  other  processes  of  morphine 
assaying.  This  process  compares  favorably  with  the  Helfenberger 
method,  and  withi  ts  many  weighings  {Helfenberger  Annalen).  No 
second  assay  is  required  of  the  morphine  itself.  The  simplicity  ot 
operation  and  the  satisfactory  quantitative  results  are  especially  to 
be  commended.  The  acidity  of  the  wine,  used  in  vinum  opii,  has  to 
regulate  the  amount  of  ammonia,  which  must  be  slightly  in  excess  ■ 
usually  2  cc.  answered  the  purpose. 
Laboratory  of  Parke,  Davis  &  Co.,  Detroit,  July,  1890. 
ARTIFICIAL  AND  NATURAL  DIGESTIONS.1 
%  By  A.  S.  Lea. 
The  following  factors,  present  in  normal  digestion,  are  absent  in 
artificial  digestion  experiments  as  usually  performed  in  flasks  and 
beakers:  (1)  Constant  movement  of  the  contents;  (2)  constant 
removal  of  digestive  products;  (3)  continuous  additions  of  fresh 
portions  of  digestive  fluid.  In  the  present  experiments,  an  appara- 
tus was  employed  which  tends  to  obviate  these  disadvantages. 
The  artificial  digestion  is  carried  out  not  in  a  flask,  but  in  a  tube  of 
parchment  paper,  kept  in  constant  up  and  down  movement  by  con- 
necting it  to  a  motor ;  this  tube  is  suspended  in  a  cylindrical  glass 
vessel,  filled  with  the  same  mixture  as  that  contained  in  the  tube, 
but  minus  any  ferment ;  an  outer  cylindrical  glass  vessel  is  filled 
with  water  kept  at  the  necessary  constant  temperature.  By  this 
means,  two  of  the  more  important  conditions  under  which  natural 
digestion  takes  place  may  be  imitated,  namely,  continuous  move- 
ment, and  removal  by  dialysis  of  digestive  products. 
The  first  question  investigated  was  the  digestion  of  starch  by 
1  J.  Physiol.,  11,  226-263.    Reprinted  from  Jour.  Chem.  Soc,  1890,  p.  536. 
