146 
Analysis  of  Peptones. 
( Am  Jour.  Pharm. 
\      March,  1891. 
pare  another  crop  of  crystals.  I  had  pledged  myself,  moreover,  to 
give  these  short  communications  at  this  meeting,  and  have  endeav- 
ored to  do  so,  incomplete  as  one  of  them  is,  promising  that  should 
success  attend  further  experiments  to  give  the  results  at  a  future 
meeting. — Phar.  Jour,  and  Trans.,  Jan.  24. 
\  /  ANALYSIS  OF  PEPTONES1 
By  A.  Denayer. 
The  author  considers  the  method  of  precipitating  the  albumose- 
peptone,  as  recommended  by  G.  Bruylants,  inaccurate,  since  muci- 
lage is  precipitated  by  ammonium  sulphate  solution.  He  recom- 
mends the  following  method  for  the  complete  analysis  of  peptones : 
Mticilage :  1-2  grams  of  peptone  is  treated  with  water  and 
precipitated  with  Mayer's  potassium  mercury  iodide  solution 
(49-801  grams  potassium  iodide,  13-546  grams  mercuric  chloride, 
1,000  cc.  water),  filtered,  washed,  concentrated  to  a  few  cc, 
saturated  solution  of  ammonium  sulphate  added,  and  the  mix- 
ture heated  to  boiling,  whereby  the  mucilage  is  precipitated.  The 
precipitate  is  washed  by  decantation,  then  with  ammonium  sulphate, 
and,  lastly,  rapidly  with  cold  water ;  the  double  iodide  is  separated 
with  boiling  alcohol,  and  the  mucilage,  with  adhering  ammonium 
sulphate,  is  weighed.  The  ammonium  sulphate  is  determined,  and 
its  weight  deducted.  Albumose-peptone :  1-2  grams  of  peptone  is 
treated  with  5  cc.  of  water,  the  mucilage  and  albumose  precipitated 
with  ammonium  sulphate,  and  the  precipitate  weighed,  from  which 
is  deducted  the  weight  of  mucilage  and  ammonium  sulphate.  Pep- 
tone:  1-2  grams  of  substance  is  dried  in  a  vacuum  at  6o°,  whereby 
the  substance  swells  up,  and  is  then  washed  with  95  per  cent, 
alcohol.  The  residue  is  dissolved  in  a  few  cc.  of  water,  and  an 
excess  of  sodium  phosphotungstate  added.  The  precipitate,  con- 
sisting of  mucilage,  albumose  and  peptone,  is  weighed  on  a  tared 
filter.  It  is  then  incinerated,  and  the  weight  of  the  ash,  as  also  the 
weights  of  the  mucilage  and  albumose,  deducted  from  that  of  the 
whole  precipitate,  the  difference  being  peptone.  Unchanged  sub- 
stances, consisting  of  amido-bases,  fatty  acids,  and  amido-acids,  are 
determined  in  the  alcoholic  extract.    Taurine,  dextrose  and  gly- 
1  Chem.  Centr.,  1890,  i,  1084 ;  from  Revue  Internal.  Scientif.,  3,  168 ;  Jour. 
Chem.  Soc,  1890,  p.  1351. 
