360 
Albumoses  and  Peptone. 
Am.  Jour.  Pharrru 
July,  1893. 
ALBUMOSES  AND  PEPTONE.1 
By  W.  Kuhne. 
Solutions  containing  a  mixture  of  albumoses  and  peptone  give  a 
precipitate  of  albumoses  when  saturated  with  ammonium  sulphate, 
the  peptone  remaining  in  solution.  After  filtration,  the  filtrate,  if 
set  aside,  will  subsequently  give  a  further  precipitate  if  more  salt  is 
added.  This  has  been  explained  by  supposing  that  the  saturation 
was  in  the  first  instance  incomplete,  or  that  the  peptone  is  partially 
changed  back  into  albumose.  The  present  research  shows  that  the 
former  is  the  more  probable  explanation.  There  are  many  precau- 
tions necessary,  in  order  to  precipitate  the  last  traces  of  albumose. 
It  is  necessary  in  the  first  instance  to  use  large  volumes  of  the  satu- 
rated solution  in  addition  to  merely  adding  crystals  of  the  salt  to  the 
proteid  mixture.  Further,  it  is  found  that  whereas  the  greater  part 
of  the  albumose  is  precipitated  by  the  salt  if  the  reaction  of  the  mix- 
ture is  made  acid,  the  residue  which  is  difficult  of  precipitation  comes 
down  more  readily  if  the  reaction  is  made  alkaline.  It  is  further 
necessary  after  the  solution  of  peptone  is  obtained  to  remove  the 
salt  employed ;  a  method  for  doing  this  by  the  use  of"  barium  car- 
bonate after  concentration  is  fully  described.  If  pancreatic  juice 
has  been  used  for  the  preparation  of  peptone,  care  also  must  be  taken 
that  leucine  and  tyrosine  are  removed  also.  In  drying,  concen- 
trating, etc.,  especially  if  sulphuric  acid  is  used,  a  brownish  product 
is  formed ;  this  is  minimized  by  care  in  the  manipulations.  This 
substance  is  precipitable  by  ammonium  sulphate,  it  is  not,  however, 
albumose  ;  it  gives  no  biuret  reaction.  Further,  if  a  precipitate  forms 
in  dialysis,  it  is  not  necessarily  of  proteid  nature ;.  if  hard  water  is 
used,  it  may  be  calcium  sulphate. 
Pekelharing  does  not  seem  to  have  noticed  the  necessity  of  these 
and  other  precautions  and  details,  and  much  of  the  present  paper  is. 
polemical,  showing  Pekelharing's  supposed  errors,  and  pointing  out 
that  there  are  more  differences  between  peptones  and  albumoses  than 
a  mere  difference  of  solubility  in  ammonium  sulphate. 
Diffusibility  of  Albumoses  and  Peptone. —  Hetero-albumose  is  the 
least  difTusible  of  the  albumoses ;  in  neutral  saline  solutions  it  is  pre- 
cipitated, and  there  is  no  loss  in  dialysis.  Dissolved  in  ammonia  it 
loses  5 -22  per  cent.    Deutero-albumose  comes  next  (loss  24-1  per 
1  Zeit.  Biol.,  29,  1-40  ;  Jour.  Chem.  Soc,  Abst.  I,  233. 
