512 
Commercial  Nitrite  of  Soda. 
r  Am.  Jour.  Pharm. 
1       Oct.,  1883. 
standing  in  the  cold  a  few  days.  A  hot  solution  of  tartaric  acid  in 
1  volume  of  water,  and  IJ  volume  of  brown  oil  of  vitriol  (sp.  gr. 
1*713),  deposited  70  per  cent,  of  its  tartaric  acid  on  standing.  The 
mother-liquor,  amounting  to  260  cc,  contained  only  30  grams  of 
tartaric  acid.  The  free  sulphuric  acid,  always  present  in  crude 
tartaric  liquors,  though  in  other  ways  injurious,  thus  allows  a  greater 
proportion  of  the  acid  to  be  obtained  by  a  single  crystallization.  The 
above  observations  were  made  in  1881. — Jour.  Chem.  Soc,  July,  1883. 
COMMERCIAL  NITRITE  OF  SODA. 
By  Peter  MacEwan. 
The  purity  of  nitrite  of  soda  as  found  in  trade  at  the  present  time 
has  been  discussed  in  the  Pharm.  Journal,  [3],  xiii.,  pp.  995,  1032 
and  1052. 
The  method  of  preparing  this  salt  most  familiar  to  pharmacists  is 
that  of  the  British  Pharmacopoeia,  1864,  namely,  by  fusion  of  a 
mixture  of  nitrate  of  soda  and  charcoal.  The  investigations  of  Howard, 
Miller  and  Warrington^  showed  that  the  product  so  obtained  is  a 
mixture  of  carbonate,  hydrate,  nitrate  and  nitrite  of  soda,  the  latter  in 
varying  quantity,  never  exceeding  42  and  generally  less  than  25  per 
cent.  To  obtain  a  better  article  Mr.  Howard  suggested  that  the 
mixture  should  be  dissolved  and  fractionally  crystallized,  the  nitrite 
crystallizing  after  the  carbonate  and  nitrate.  This  undoubtedly  yields 
a  purer  nitrite,  but  it  does  not  get  rid  of  the  principal  objections  to 
the  charcoal  process,  namely,  somewhat  uncontrollable  deflagration  and 
formation  of  a  large  percentage  of  carbonate.  By  the  employment  of 
other  deoxidizing  agents,  such  as  lead  or  copper  (in  a  fine  state  of 
division),  these  objections  are  overcome,  and  a  product  obtained 
having  a  higher  percentage  of  nitrite  associated  with  nitrate  and  a 
small  proportion  of  hydrate.  This,  by  fractional  crystallization,  will 
yield  a  salt  corresponding  to  Mr.  Ekin's  description,  that  is,  containing 
"98  percent,  of  real  nitrite,  the  2  percent,  of  impurity  consisting 
chiefly  of  moisture." 
Previous  to  the  communications  of  Dr.  Hay  and  Mr.  Ekin  I  had 
had  opportunity  of  examining  several  commercial  specimens  of  the 
salt,  and  since  then  have  obtained  a  number  from  different  parts  of 
the  country.  The  following  table  shows  the  results  of  the  examination 
Pharm.  Journal^  [2],  vii.,  pp.  7,  95  and  204. 
