'^'^•/uiy^im^''"''}      Food-Preservatives  and  Diastase.  357 
Arrow-root  starch  was  selected  for  reasons  given  by  these  observers. 
To  avoid  error  due  to  varying  action  of  the  dilute  solutions  of  malt 
which  are  required  for  the  experiments,  a  blaak  experiment  was  made 
in  each  set,  and  from  this  the  diastasic  value  of  the  pure  malt  extract 
was  determined.  In  the  first  observations  maltine  was  employed,  it 
having  been  shown  by  our  previous  tests  to  be  far  the  most  active  of 
the  commercial  extracts,  but  later  Schuchardt's  diastase  was  used. 
The  Fehling's  solution  was  prepared  as  directed  by  Allen,  and  the 
determinations  were  made  volumetrically.  Many  of  the  experiments 
were  duplicated,  with  concordant  results.  ,  In  addition,  a  number  of 
tests  were  made  by  the  method  given  by  Allen  for  valuing  malt- 
extracts.  The  results  obtained  were  similar  to  those  given  below, 
but,  not  being  capable  of  quantitative  comparison,  are  not  detailed 
here. 
The  antiseptics  selected  were  salicylic  acid,  boric  acid,  sodium  acid 
sulphite,  saccharin,  beta-naphtho],  and  alcohol.  The  sample  of  beta- 
naphthol  was  of  the  form  now  sold  under  the  name  hydronaphthol. 
In  all  the  experiments  the  temperature,  time  of  action,  strength  of 
starch  solution  (30  grammes  to  litre)  were  the  same. 
In  the  following  table  the  effect  is  represented  produced  by  0.5  cc. 
of  maltine  diluted  to  5  cc,  and  added  to  100  cc.  of  starch  solution. 
The  figures  give  the  proportion  of  antiseptic  used  to  the  whole  volume 
of  solution,  and  the  amount  of  sugar  formed  from  the  starch — that 
contained  in  the  maltine  being  deducted : 
Antiseptic  used. 
Proportion. 
Fehling's  Solution  required. 
None 
245  cc. 
Salicylic  acid 
1  to  500 
No  sagar  formed. 
(<  u 
1  "  1,000 
U  (( 
1  "  20,000 
245  cc. 
Boric  acid 
1  "  1,000 
245  " 
Sodium  acid  sulphite 
1  "  1,000 
245  " 
Saccharin 
1  "  1,000 
18-5  " 
'i 
1  "  500 
5-6 
Beta-naphthol 
1  "  1,000 
204  " 
1  "  500 
174  " 
Alcohol 
1  25 
245 
In  the  above  experiments  the  antiseptics  were  added  to  the  starch 
and  the  maltine  allowed  to  act  at  once.  In  the  following,  very  small 
quantities  of  salicylic  acid  and  alcohol  were  first  mixed  with  maltine 
and  allowed  to  stand  four  days  before  addition  to  the  starch. 
