AmNo°v.%8P77arin'}  Preparation  of  Concentrated  Nitric  Acid,  537 
on  the  intensity  of  color  produced  when  the  alkaloid  is  treated  with 
chlorine  water  and  solution  of  ammonia. 
First  a  standard  solution  is  prepared  by  taking  one  centigram  of 
quinia  or  one  of  its  salts,  dissolving  it  in  about  five  cc.  of  fresh  chlo- 
rine water,  adding  ten  cc.  of  solution  of  ammonia,  and  diluting  this 
dark-green  liquid  in  a  glass  cylinder  to  100  cc. 
In  estimating  a  one-grain  quinia  pill,  for  example,  a  similar  cylinder 
is  taken,  into  which  is  placed  a  fractional  part  of  the  solution  obtained 
by  treating  the  disintegrated  pill  with  chlorine  water  and  ammonia,  and 
diluting  with  water  until  it  exactly  corresponds  in  color  with  the  stan- 
dard solution  \  then  by  a  little  calculation  the  amount  of  quinia  is 
known.  By  a  little  practice  the  results  become  surprisingly  accurate, 
and  the  process  requires  very  little  time  compared  with  the  more  exact 
gravimetric  methods.  It  is  true  that  quinidia  if  present  interferes  with 
the  results,  but  it  is  not  so  liable  to  be  fraudulently  employed  as  the 
cheaper  alkaloids. 
To  what  extent  this  process  may  be  employed  for  the  estimation  of 
quinia  and  quinidia  in  bark  I  am  not  prepared  to  say,  but  think  that, 
with  certain  precautions,  it  might  admit  of  application  for  this  purpose. 
The  same  principle  is  extensively  used  in  determining  the  amount  of 
carbon  in  iron  and  steel,  with  very  satisfactory  results. 
The  PREPARATION  of  CONCENTRATED  NITRIC  ACID. 
By  Henry  Trimble,  Ph.G. 
Read  at  the  Social  Alumni  Meeting,  October  4,  1877. 
Although  this  acid  is  rarely  used  in  pharmaceutical  laboratories  of 
greater  strength  than  the  Pharmacopoeia  standard,  yet  occasionally  that 
of  the  specific  gravity  1*5  is  found  convenient,  and  in  some  operations 
absolutely  necessary. 
All  the  authorities  which  I  have  consulted  on  the  subject,  recom- 
mend it  to  be  prepared  by  heating  in  a  retort  equal  parts  of  potassium 
nitrate  and  sulphuric  acid.  This  process  requires  a  high  heat,  constant 
attention,  and  is  very  liable  to  terminate  in  fracture  of  the  retort.  The 
following  method,  I  understand,  is  employed  in  some  of  the  German 
laboratories,  and,  having  tried  it  a  great  many  times  myself,  I  think  it 
should  be  recommended,  supposing  that  commercial  nitric  acid  is  as 
readily  procured  as  potassium  nitrate. 
