Ain.  Jour.  Pharm.\ 
August,  1901.  > 
Chromic  Acid  and  the  Chromates. 
395 
In  addition  to  the  proteolytic  and  rennet  ferments  noted,  and  the 
probable  presence  of  pectase,  there  is  present  in  the  papaw  latex, 
amylolytic  ferment  capable  of  acting  upon  cooked  starch.  The 
amount  of  this  starch- converting  ferment  is  not  large,  or  else  it  is 
weak.  The  fresh  latex  acts  promptly  upon  starch  paste,  thinning  it, 
and  converting  a  portion  at  least  into  soluble  starch  and  dextrin. 
(The  amount  of  reducing  sugar  produced  is  slight.) 
The  starch-converting  action  of  the  separated  ferment  (or  dried 
latex)  is  not  very  pronounced.  The  most  that  can  be  said  is  that 
it  is  present.23 
Altogether  we  are  warranted  in  the  statement,  that  the  digestive 
action  of  the  ferments  contained  in  the  papaw  latex  and  the  pro- 
ducts formed  in  such  are  quite  identical  with  that  of  the  animal  and 
vegetable  ferments  in  general. 
A  RAPID  METHOD  FOR  DETERMINING  THE  VALUE 
OF  -  CHROMIC  ACID"  AND  THE  SOLUBLE  CHROMATES. 
By  Lyman  F.  Kebeer,  B.S. 
The  principle  involved  in  the  beautiful  and  exact  method  for 
estimating  iodine  by  means  of  sodium  thiosulphate  was  brought 
forward  by  A.  du  Pasquier,1  but  the  original  method  gave  neither 
satisfactory  nor  concordant  results.  Bunsen  -  took  up  the  process 
and  pointed  out  the  cause  of  its  shortcomings.  These  researches 
on  the  volumetric  estimation  of  iodine,  in  connection  with  Schwarz's  3 
proposed  use  of  sodium  thiosulphate  instead  of  sulphurous  acid, 
produced  a  very  beneficial  effect  on  the  whole  domain  of  chemical 
analysis.  The  value  of  the  process  is  not  so  much  in  the  estimation 
of  iodine  in  iodine  compounds,  but  rather  in  the  determination  of 
such  substances  as  will  liberate  iodine  when  brought  in  contact 
with  potassium  iodide,  either  by  direct  displacement  [e.  g.,  the 
chlorinated  compounds,  chlorine  water,  bromine,  etc.)  or  by  reduc- 
tion in  the  presence  of  hydrochloric  acid,  either  with  or  without 
23  The  pronounced  amylolytic  action  of  some  of  the  papaw  ferments  in  the 
market  is  probably  due  to  the  addition  of  diastase. 
1 1840,  Anal,  de  Chimie  et  de  Physique,  73,  310  ;  Silliman's  Jour.,  40,  123. 
2  1853,  (Liebig)  Anal.,  86,  265-291. 
3 1853,  Anleit.  zu  Maassanal.  Nachtrdge,  22. 
