280  Amy  I  Nitrite  and  Nitrous  Ether.  {^'i^ml™' 
A  specimen  of  sodium  nitrite,  sold  as  meeting  the  U.S. P.  require- 
ments (not  less  than  97-3  per  cent,  pure)  was  assayed  by  the  new- 
method,  which  gave  98-8  and  98-5  per  cent.,  and  also  by  the  gaso- 
metric  method,  which  gave  100-3  and  100  9  per  cent.,  correction 
being  made  for  temperature  only.  The  figures  obtained  by  the  lat- 
ter method  are  evidently  too  high,  and  the  error  is  perhaps  mainly 
caused  by  the  failure  to  make  correction  for  pressure  and  vapor  ten- 
sion, which  might  easily  have  reduced  them  to  98  per  cent.  The 
results  of  the  new  method  are,  without  doubt,  nearer  the  actual 
percentage.  This  still  leaves  unexplained  the  fact  that  the  old 
method  invariably  gives  considerably  lower  results  than  the  new  in 
the  estimation  of  ethereal  nitrites.  The  surmise  that  it  might  be  par- 
tially due  to  an  increase  in  solubility  of  nitric  oxide  in  the  nitro- 
meter liquid,  through  presence  of  alcohol,  was  disposed  of  by  par- 
allel estimations  of  sodium  nitrite  with  and  without  alcohol.  The 
last  estimations  recorded  were  repeated  immediately,  under  the 
same  conditions  of  atmospheric  pressure,  temperature,  etc.",  but  with 
addition  of  5  c.c.  of  alcohol  to  the  aqueous  solution  of  sodium  nitrite 
in  the  nitrometer  before  adding  the  reagents.  Instead  of  being 
lower,  the  results  were  a  little  higher,  101-3  and  ioi-o  per  cent. 
An  old,  deteriorated  specimen  of  potassium  nitrite,  which  gave 
78-3  and  78  6  per  cent,  by  the  new  method,  assayed  8o-i  and 
79  6  per  cent,  by  nitrometer,  corroborating  the  results  obtained  on 
the  sodium  nitrite. 
There  was  still  a  possibility  that  some  of  the  by-products  that 
usually  accompany  ethyl  nitrite  in  addition  to  aldehyde,  such  as 
ethyl  formate,  acetate,  oxalate  and  ethyl  ether — and  the  correspond- 
ing ones  in  the  case  of  amyl  nitrite — might  be  accountable  for  the 
high  figures  given  by  the  new  method.  The  fact  that  the  differ- 
ences in  the  results  of  the  two  methods  are  in  fairly  uniform  ratio, 
for  products  from  different  sources  and  doubtless  varying  methods 
of  preparation,  however,  makes  this  very  improbable.  To  settle  this 
point,  the  following  experiment  was  made :  To  an  aqueous  solution 
of  about  8  grammes  of  the  same  sodium  nitrite  as  had  been  used  in 
previous  experiments,  0-5  gramme  each  of  sodium  formate  and 
sodium  oxalate,  and  0-5  c.c.  each  of  ether,  ethyl  acetate,  and  paral- 
dehyde were  added,  and  the  solution  assayed  in  the  same  manner  as 
had  been  done  without  addition  by  the  new  method.  This  gave 
95  2  and  94- 5  per  cent.,  instead  of  98  5  and  98-8  per  cent.,  which 
