^"jine'imr }  Extract  of  Malt.  293 
Boiled  potatoes,  4  parts  in  3  minutes  ;  16  parts  in  15  minutes, 
rice,        4    "     "  10 
bread,     4    "     "9      "  16     "    "  45 
crackers,  4    "     "5      "  16     "    "  25 
sago,       4    "     "  12      "  8     "    "  30 
The  following  experiments  made  with  the  view  of  studying  the 
influence  of  acids  and  alcohol  on  diastase  and  the  conversion  of  starch 
are  produced  in  tabular  form  in  comparison  with  saliva.  They  may 
interest  many  readers,  and  encourage  them  to  similar  investigations. 
The  experiments  were  conducted  as  follows  : 
1.  A  paste  was  made  by  boiling  starch  in  water  until  it  was 
thoroughly  gelatinous,  5  fluidounces  containing  exactly  100  grains  of 
starch ;  the  specific  gravity  of  this  paste  was  I'OllT. 
2.  For  each  experiment,  5  fluidounces  of  the  paste  were  mixed  in 
a  porcelain  capsule  with  200  minims  of  a  mixture  of  equal  parts  of 
malt  extract  and  water.  The  malt  solution  was  freshly  prepared  each 
day  from  the  same  sample  of  malt  extract,  and  tested,  to  secure  a 
uniformity  of  diastatic  power.  In  the  experiments  with  saliva,  100 
minims  were  added  to  the  5  fluidounces  of  starch  paste.  The  saliva 
was  collected  from  a  number  of  persons,  both  adults  and  children, 
and  was  tested  from  time  to  time.  The  saliva  always  gave  a  neutral 
reaction,  while  the  malt  extract  always  gave  an  acid  reaction,  owing 
to  the  presence  in  the  latter  of  -^-q  per  cent,  of  acid  calculated  as 
lactic  acid. 
3.  Before  adding  the  malt  extract  solution  or  saliva,  the  starch  paste 
was  by  means  of  a  water-bath  brought  to  a  temperature  of  100°  F., 
and  maintained  at  a  temperature  ranging  from  95°  to  100  F.  until 
the  experiments  were  completed. 
4.  The  acids  or  alkalies  were  always  added  to  and  thoroughly 
mixed  with  the  paste  before  adding  the  malt  extract  solution  or 
saliva. 
5.  When  the  change  in  the  condition  of  the  starch  paste  operated 
on  was  very  rapid,  it  was  tested  every  minute  with  iodine,  otherwise 
every  five  minutes.  In  a  few  instances  the  action  was  so  rapid  that 
tests  were  required  to  be  made  in  fractions  of  a  minute. 
6.  The  iodine  solution  was  made  and  used  as  described  above. 
7.  Except  in  a  few  instances,  the  experiments  were  discontinued  at 
the  end  of  an  hour. 
8.  The  acids  were  calculated  as  anhydrous. 
