186 
Determination  of  Ethyl  Nitrite. 
Am.  Jour.  Pliarm. 
April,  1885. 
gas.  When  strictly  accurate  results  are  not  required,  the  volume  of 
gas  need  not  be  corrected  for  variations  of  pressure,  temperature,  and 
tension  of  aqueous  vapor,  and  if  these  considerations  be  omitted  the 
calculation  is  much  simplified.  Thus,  if  0*030  gram  of  nitric  oxide 
(representing  0'075  gram  of  C2H5NO2)  under  the  ordinary  conditions 
of  pressure  and  temperature  be  taken  to  measure  23*55  cc,  then 
If  the  density  of  the  sample  be  omitted  from  the  equation,  the  result  j 
will  be  the  number  of  grams  of  ethyl  nitrite  per  100  cc.  of  the  sample. 
The  nitrometer  method  has  been  proved  to  give  very  good  results  with 
pure  sodium  nitrite  (prepared  from  silver  nitrite)  employed  in  known  \ 
amount.    The  results  with  spirit  of  nitrous  ether  are  somewhat  higher  ; 
than  those  given  by  Eykman's  method,  the  differeiice  being  least  when  : 
sodium  chloride  is  employed  in  the  latter  process  and  time  given  for  ^ 
the  ferrous  solution  to  react  thoroughly  on  the  solution  of  ethyl  nitrite.  1 
The  results  by  the  iodide  method  are  almost  certainly  more  accurate  \ 
than  those  by  Eykman's  process.    With  most  specimens  of  sweet  { 
spirit  of  nitre,  a  considerable  amount  of  nitric  oxide  is  produced  (and  j 
iodine  liberated)  before  adding  the  acid,  the  reaction  probably  depend-  ' 
ing  on  the  presence  of  free  acid  in  the  sample.    The  results  obtained  \ 
in  the  nitrometer  are  remarkably  constant,  and  the  method  furnishes  a  ' 
very  easy  means  of  assaying  sweet  spirit  of  nitre  with  considerable 
accuracy,  which  is  further  increased  if  a  correction  of  1*5  cc.  (=  0.0048  ] 
gram  of  CoH^NOg)  be  made  for  solubility  of  the  gas.    The  process  \ 
has  the  advantage  of  great  ease  and  rapidity,  and  actually  measures  \ 
the  nitrous  compounds  present  in  the  sample,  instead  of  leaving  their  <, 
proportions,to  be  iilferred  from  a  more  or  less  complex  reaction,  such  J 
as  the  reduction  of  permanganate,  etc.    The  following  results  were  |i 
obtained  by  me  from  six  typical  samples.    No  correction  was  made  J, 
for  pressure  or  solubility,  the  figures  representing  the  actual  volumes  of 
gas  measured  at  about  15°  C. 
volume  of  gas  in  cc.  x  0-3185 
percentage  bj-  weight  of  C2H5NO2. 
measure  ol  sample  in  cc.  X  density  of  sample 
Volume  of 
NO  from 
5cc. 
Weight  of 
C2H5NO2 
per  cent. 
NO  from 
5  cc. 
1.  25  per  cent.  sol.  in  absolute  alcohol  (two  months 
cc. 
(290-0  _  from 
Milligrams. 
923-6 
22-02 
old  
2.  Spt.  Nitrous  Ether  B.  P.  (two  tnonths  old) 
3.  Spt.  Nitrous  Ether  B.  P.  (age  unknown)  
4.  Spt.  Nitrous  Ether  B.  P.  (age  unknown).... 
5.  "Spt.  .Ether.  Nit.  8-50"  (new)  
6.  Sp.  .Ether.  Nit.  Dulc.  -900"  (new)  
2-98 
2-63 
2-62 
14  -7 
22-0 
