Am"jiiyri884arm*}  Spiritus  JEtheris  Nitrosi.  381 
nitric  acid  in  presence  of  the  nitrous,  are  inapplicable  in  this  case.  It 
is  questionable,  hoAvever,  if  nitric  acid  can  exist  as  such  in  presence  of 
the  readily  oxidizable  constituents  of  the  spirit.  I  have  therefore 
calculated  the  inorganic  acid  as  nitrous  acid  (HN02). 
The  free  acids  were  determined  volumetrically,1  semi-normal  solu- 
tion of  soda  was  used,  methyl  orange  being  taken  to  indicate  nitrous 
acid  and  phenolphthalein  to  indicate  total  acidity.  The  method  is 
certainly  not  free  from  objection,  the  sources  of  error  being  (1)  de- 
composition— that  is,  further  acidity — of  the  spirit  during  the  esti- 
mation, and  (2)  decomposition  of  the  methyl  orange  by  free  nitrous 
acid.  The  first  error  can  be  limited  by  rapid  manipulation,  use  of 
undiluted  spirit  and  a  small  flask.  The  second  is  not  so  rapid  in  its 
action  as  to  preclude  indication,  and  by  using  the  methyl  orange  exter- 
nally as  well  as  internally,  the  error  is  minimized.  In  the  method  we 
take  10  cc.  of  the  spirit,  which  is  put  into  a  50  cc.  flask,  in  which  a 
drop  of  phenolphthalein  has  previously  been  put,  then  two  or  three 
drops  of  methyl  orange  solution  are  put  in.  Before  the  estimation  is  com- 
menced several  spots  of  methyl  orange  solution  are  placed  on  a  white  plate, 
and  a  glass  rod  should  be  at  hand.  The  standard  solution  is  quickly 
but  carefully  dropped  into  the  flask,  and  as  soon  as  the  red  color  of  the 
methyl  orange  begins  to  fade,  the  glass  rod  should  be  clipped 'in  and 
brought  into  contact  with  a  methyl  orange  spot  on  the  plate.  If  the 
spot  assume  a  strong  pink  color,  we  have  an  indication  that  the  nitrous 
acid  is  not  quite  neutralized,  so  the  addition  of  standard  solution  is 
continued  until  the  methyl  orange  spot  becomes  but  feebly  pink.  The 
volume  of  standard  solution  used  is  noted,  and  the  titration  continued 
until  the  phenolphthalein  indicates  alkalinity.  The  first  portion  used 
is  calculated  for  nitrous  acid  and  the  second  for  acetic  acid. 
In  the  following  table  the  results  of  several  observations  are  given 
in  percentages,  the  proportion  of  ethyl  nitrite  and  aldehyde  (as  far  as 
determined)  being  also  given.  I.  to  IV.  are  B.B.  spirit  (a  and  /3  of 
the  separation  paragraph  are  II.  and  III.) ;  VII.  is  B.P.  raised  to 
*850,  and  the  others  are  the  *850  of  Lond.  Phar. 
Having  before  us  these  tabulated  results  of  the  effect  of  deteriora- 
tion on  the  specific  gravity,  separation  volume  and  acidity  of  the  spirit, 
we  may  now  discuss  the  causes  of  decomposition  and  deterioration. 
1  In  Mr.  Rimmington's  method  the  spirit  is  unduly  exposed  to  atmo- 
spheric influence  and  the  action  of  water. 
