AVa°rch,S!'m'}  Method  of  Testing  Diastatic  Substances.  143 
shallow  tin  pan,  2  inches  deep,  8  inches  in  diameter;  (3)  two  1  c.c. 
pipettes  graduated  to  tenths ;  (4)  eight  large  glasses  or  tumblers  of 
about  150  c.c.  capacity  each;  (5)  ten  small  test  tubes;  (6)  one  100 
c.c.  cylinder;  (7)  two  white  dinner  plates. 
Process  of  Testing.—- F 'our  into  each  of  the  eight  glasses  ico  c.c. 
of  the  hot  starch  paste.  Place  them  side  by  side  in  the  shallow  pan 
of  warm  water  at  about  400  C.  Measure  into  the  first  glass  1  c.c. 
of  the  saliva  or  other  liquid  to  be  tested.  Pour,  of  the  standard 
diastase  solution,  in  quick  succession  : 
Into  the  second  glass   1  c.c. 
Into  the  third  glass   2  c.c. 
Into  the  fourth  glass  ...    3  c.c. 
Into  the  fifth  glass   4  c.c. 
Into  the  sixth  glass     5cc. 
Into  the  seventh  glass     6  c.c. 
Into  the  eighth  glass   7c. c. 
Then  the  contents  of  each  glass  is  stirred  with  the  test  tube  as  a 
stirring  rod  in  quick  succession,  until  the  starch  paste  all  becomes 
limpid.  At  this  stage  it  will  be  observed  that  the  stronger  the 
diastatic  power  the  quicker  the  liquefaction  of  the  paste.  When 
the  contents  of  the  glasses  become  liquefied,  take  out  of  each  glass 
in  succession  a  drop  of  the  liquid  by  means  of  the  stirring  test  tube, 
and  drop  on  a  white,  dry  dinner  plate  in  the  order  of  the  glasses. 
When  there  are  eight  drops  of  equal  size  on  the  plate,  drop  on  each 
one  drop  of  the  iodine  solution.  Then  spread  each  sample  with  the 
finger  to  about  the  size  of  a  silver  dollar.  Ihe  drops  from  the 
second  to  the  eighth  glass  will  form  a  colorometric  scale  from  blue 
to  purple  and  reddish-brown.  Observe  now  which  member  of  the 
scale  corresponds  to  the  color  of  the  one  containing  the  saliva.  The 
comparison  is  made  more  certain  by  repeating  the  tests  within  the 
first  ten  minutes  after  the  saliva  is  put  in. 
Suppose  the  color  corresponds  to  somewhere  between  the  fourth 
and  fifth,  then  we  can  assume  it  at  4-5,  and  calculate  the  diastatic 
strength  in  terms  of  starch  converted  or  sugar  formed  ;  or,  if  further 
accuracy  of  the  test  is  desired,  a  scale  of  starch  glasses  containing 
standard  diastase  solution  of  4  c.c,  4-2  c.c,  4  4  c.c,  46  c.c,  4-8  c.c, 
and  5  c.c,  may  be  put  up  and  compared  with  1  c  c.  of  the  given 
saliva  in  the  same  manner. 
Instead  of  having  only  one  specimen  at  a  time,  several  samples  of 
saliva  or  other  diastatic  substances  can  be  tested  at  once. 
