Am.  Jour.  Pharni. 
Nov.,  1884. 
Milk. 
593 
increased,  and  the  calcium  phosphate  plays  no  active  part  in  the  for- 
mation of  the  curd. 
From  the  above  table,  it  appears  that  0  46  of  the  colloidal  casein  has 
not  been  converted  into  the  solid  form,  and  it  is  found  that  the  whole 
of  the  coagulable  casein  is  never  precipitated,  although  the  amount 
remaining  in  solution  diminishes  if  the  proportion  of  rennet  is 
increased.  Milk  may  be  regarded  as  a  system  in  which  the  three 
forms  of  casein  are  in  equilibrium,  this  equilibrium  being  distrubed 
by  the  addition  of  minute  quantities  of  inorganic  salts,  ferments,  etc. 
Coagulation  corresponds  to  the  slow  and  regular  production  in  a  liquid 
mass  of  a  state  of  equilibrium  which  requires  the  solidification  of  a 
dissolved  substance,  but  there  is  no  evidence  to  show  why  part  of  the 
casein  should  be  precipitated  in  presence  of  rennet.  The  explanation 
is  not  to  be  sought  in  any  specific  properties  of  rennet,  for  other  sub- 
stances produce  the  same  effect,  nor  in  the  specific  properties  of  casein, 
since  other  bodies,  such  as  oxide  of  iron,  can  exist  in  the  same  three 
states.  Coagulation,  in  fact,  appears  to  be  simply  a  problem  in  mole- 
cular mechanics  which  cannot  be  solved  in  the  present  state  of  our 
knowledge. —  Compt.  rend.,  98,  438-441,  and  526-528;  Jour.  Chem. 
Soc,  July,  1884,  p.  762. 
Determination  of  the  value  of  extract  of  malt. — H.  Tiesler, 
St.  Petersburg,  examined  eight  samples  of  malt  extract  by  Jungk's 
method  ("Amer.  Jour.  Pharm.,"  1883,  p.  291)  for  determining  the 
diastatic  value.  In  order  to  avoid  the  possible  liquefying  action  upon 
starch  of  the  free  acid  present,  this  was  neutralized  with  baryta  water. 
Five  of  the  samples  contained  no  diastase,  the  remaining  three  variable 
proportions  of  the  same.  The  rapidity  with  which  the  malt  extracts 
liquefied  starch  paste  was  estimated  by  means  of  a  flat  vessel  having 
on  the  bottom  a  short  thin  discharge  pipe  through  which  in  one  minute 
46*56  Ccm.  of  distilled  water  of  15°  C.  would  run  off.  The  mixtures 
of  malt  extract  and  starch  were  digested  for  a  certain  length  of  time, 
then  rapidly  cooled  to  15°  C.  and  carefully  strained,  when  one  sample 
discharged  after  one  minute's  action  44*57  Ccm.,  and  after  twelve 
hour's  45*37  Ccm.,  while  the  other  sample  discharged  only  37*01  and 
40*89  Ccm.  respectively. 
The  author  advises  also  the  concentration  of  malt  extract,  so  that  it 
contain  not  less  than  80  per  cent,  of  dry  matter.  In  dilute  solutions  the 
diastatic  power  is  more  or  less  rapidly  decreased. — Phar.  Zeitschr.  f. 
Russl,  1884,  pp.  297-301. 
38 
