278        Recent  Literature  Relating  to  Pharmacy.  {*m'jv£lm"m' 
a  few  minutes,  with  occasional  agitation ;  after  filling  flask  to  100 
c.c.  mark  with  water,  should  require  for  neutralization  of  50  c.c.  of 
the  decanted  and  clear  liquid,  not  less  than  21  c.c,  nor  more  than 
2-4  c.c.  normal  hydrochloric  acid,  phenolphtalein  being  the  indi- 
cator. 
Each  cubic  centimeter  of  normal  alkali  employed  in  abstracting 
the  acid  radicle  from  the  subnitrate  (represented  by  difference  be- 
tween amount  employed  and  amount  shown  on  titration)  is  equiva- 
lent to  0*054  grammes  N2Os.  The  figures  given  above  indicate  14 
to  15-6  per  cent.  N205,  which  the  author's  examination  show  to  be 
the  average  standard. 
O.  Spindler  {loc.  cit.,  1898,  375)  finds  the  volumetric  estimation  of 
the  subnitrate,  as  outlined  above,  usually  defective,  as  most  normal 
potassium  hydrate  contains  carbonate.  He  heats  to  boiling  a  mix- 
ture of  about  2  grammes  subnitrate  with  a  little  water,  and  25  c.c. 
normal  alkali,  whereby  bismuth  hydrate  is  produced.  After  cooling, 
the  mixture  is  neutralized  with  normal  hydrochloric  acid,  after  which 
10  c.c.  titrated,  25  per  cent,  acid  is  added,  when  the  bismuth  goes  into 
solution  as  chloride,  then  10  c.c,  normal  ammonium  chloride  solu- 
tion (5*35  grammes  to  100  c.c.)  is  added  and  the  solution  neutralized 
with  normal  alkali,  when  bismuth  oxychloride  precipitates. 
The  mixture  is  then  transferred  from  the  200  c.c.  flask  heretofore 
used,  to  one  holding  500  c.c,  and  water  is  added  to  bring  the  mix- 
ture to  the  latter  volume.  It  is  then  filtered  and  10  cc.  of  the  fil- 
trate is  titrated  with  ^  normal  silver  nitrate. 
The  quantity  of  bismuth  is  calculated  by  subtracting  the  amount 
of  Ji^  normal  silver  nitrate,  required  for  500  cc  of  the  filtrate,  from 
the  amounts  of  all  the  ^  normal  hydrochloric  acid  and  fa  normal 
ammonium  chloride  employed.  The  difference  will  represent  the 
amount  of  y1^  normal  silver  nitrate  required  for  the  chlorine  in  the 
precipitated  bismuth  oxychloride,  and  this  figure,  in  cubic  centi- 
meters, multiplied  by  the  factor  0-02595,  will  give  the  actual  amount 
of  oxychloride  through  which  the  bismuth  strength  of  the  subni- 
trate can  be  estimated. 
MALIC  ACID  OF  THE  CRASSULACE^i. 
There  has  been  much  discussion  as  to  identity  of  the  malic  acid 
obtained  from  plants  of  N.O.  Crassulaceae. 
Braconnet,  its  discoverer,  thought  it  identical  with  the  usual  malic 
