156  Analysis  of  Peptones.  {AV«c£.3&r,n* 
difference  being  taken  as  albumose.  In  the  second  portion  both 
albumose  and  peptone  are  precipitated  by  phospho-tungstic  acid. 
In  the  precipitate,  nitrogen  is  estimated  by  the  Kjeldahl  process. 
Multiplying  the  nitrogen  by  6-25,  albumose  and  peptone  are  found, 
and  so,  of  course,  peptone  by  difference. 
(4)  .A.  Denaeyer.  (Bull,  de  V Assoc.  Beige  des  Chimistes,  March, 
1890.  Analyst,  June,  1890.)  In  this  memoir  it  was  shown  that 
gelatin  had  been  confounded  with  albumose  in  previous  researches. 
Gelatin  in  all  forms  is  precipitated  by  ammonium  sulphate,  so  that 
the  albumose  found  by  the  methods  of  Kiihne  and  Chittenden,  and 
Kbnig  and  Kisch  was  really  a  mixture  of  albumose  and  gelatin.  If 
albumin  and  albumose  are  previously  separated,  gelatin  may  be 
precipitated  completely  by  ammonium  sulphate.  It  is  unnecessary 
to  describe  the  analytical  method  founded  on  this  important  dis- 
covery, as  it  has  been  improved  in  a  subsequent  paper  by  the  same 
author. 
(5)  A.  Denaeyer.  {Bull,  de  I' Assoc.  Beige  de  Chimistes,  Decem- 
ber, 1890.  Analyst,  May,  1891  ;  see  also  Am.  Jour.  Pharm.,  1891,. 
p.  146.)  This  memoir,  recently  translated  and  published  with  an 
addendum  by  Straker  and  Sons,  London,  contains  later  results  of 
M  Denaeyer's  work.  The  analytical  method  which  is  described — 
although  it  is  based  upon  those  which  preceded  it — shows  a  distinct 
advance.  Our  own  process  is  but  a  modification,  and,  we  thinkr  an 
improvement  upon  it.  M.  Denaeyer's  system  may  be  summarized 
as  follows : — 
(a)  The  peptonic  fluid  is  treated  with  strong  alcohol.  After 
standing  for  24  hours  the  precipitate,  which  consists  of  albumin, 
albumose,  coagulable  gelatin  and  peptone,  is  washed  with  alcohol, 
dried  and  weighed.  The  solution  is  then  divided  into  two  portions, 
which  are  separately  treated  (b  and  c). 
(6)  One  portion  of  the  alcoholic  solution  is  evaporated  to  dryness 
and  extracted  with  warm  water.  Excess  of  saturated  solution  of 
ammonium  sulphate  is  then  added,  and  the  mixture  warmed.  On 
cooling,  the  gelatin  soluble  in  alcohol  adheres  to  the  basin,  and  may 
be  washed  slightly  with  ice-cold  water,  dried  and  weighed.  It  is 
then  re-dissolved  in  warm  water,  and  the  ammonium  sulphate  in  it 
estimated  by  barium  chloride  and  deducted  from  the  weighed 
gelatin. 
(c)  The  second  portion  of  the  alcoholic  solution  is  evaporated  to 
