Am.  Jour.  Pharm. ) 
June,  1883.  J 
Extract  of  Malt. 
291 
A  certain  weight  of  extract  is  dissolved  in  an  equal  weight  of  water, 
the  specific  gravity  of  this  solution  at  17.5°C.  is  determined  and  from 
the  table  given  the  percentage  of  extract  is  ascertained.  On  sub- 
tracting the  extract  from  100  the  percentage  of  water  is  found. 
A  good  extract  containing  both  diastase  and  albumen,  seldom  con- 
tains more  than  25  per  cent,  of  ^^ater.  Should  the  percentage  of 
extract  fall  to  50  or,  as  with  many  so-called  beers,  to  5  or  6  per  cent, 
diastase  cannot  be  present,  as  it  would  not  keep  in  such  diluted  liquids. 
To  such  preparations  salicylic  acid  is  usually  added  to  prevent  for 
some  time  the  decomposition  of  the  dextrin.  On  agitating  such  a  pre- 
paration with  strong  ether,  the  salicylic  acid  is  easily  separated.  Eva- 
porate the  ethereal  solution,  dissolve  the  residue  in  water  and  test  this 
solution  with  diluted  ferric  chloride,  when  the  salicylic  acid  is  easily 
recognized  by  the  violet  color  produced.  If  we  reflect  that  the  addi- 
tion of  one-fourth  to  one-half  per  cent,  of  salicylic  acid  to  solutions  of 
starch  renders  even  preparations  very  rich  in  diastase  inactive,  it  becomes 
obvious  that  the  addition  of  this  acid  to  an  extract  of  malt  is  incorrect. 
Determination  of  free  acid. — The  free  acid  of  freshly  prepared 
extract  of  malt  is  almost  exclusively  lactic  acid,  but  with  the  age  of  the 
preparation  other  acids  are  formed,  and  for  this  reason  I  estimate  the 
amount  of  caustic  soda  used  and  note  this  as  percentage.  In  a  solution 
of  pure  caustic  soda,  5  grams  to  1,000  cc.  water,  each  cc.  rcipresents 
0.005  sodium  hydrate.  10  grams  of  extract  are  dissolved  in  100 
grams  of  water  and  neutralized  with  the  soda  solution.  For  this  pur- 
pose a  burette  graduated  into  one-tenth  cc.  is  used,  and  the  point  of 
neutralization  determined  by  means  of  very  sensitive  litmus  paper. 
With  a  little  practice  the  estimation  of  the  acid  does  not  present  any 
difficulty.  Good  extract  of  malt  tested  by  this  method,  will  seldom 
require  more  than  6  to  7  cc.  soda  solution. 
To  take  an  example,  suppose  6  cc.  soda  solution,  that  is,  6  X  0.005= 
0.030  hydrate  of  sodium  to  be  necessary  for  complete  neutralization  of 
10  grams  of  extract  of  malt,  then  100  grams  of  extract  must  need 
0.30  sodium  hydrate.  If  for  100  parts  of  extract  of  malt  more  than 
0.5  sodium  hydrate  should  be  required,  the  durability  of  tlie  prepara- 
tion will  be  doubtful  and  the  diastastic  power  will  soon  disappear. 
Estimation  of  Diastastic  Strength. — Twelve  clear  and  uniform  2  oz. 
vials  each  filled  with  2  oz.  distilled  water  and  2  drops  of  Iodine 
solution,  prepared  from  2  grams  Iodine,  4  grams  Iodide  of  Potassium 
