Am'Aprii',  Srm* }  Preservation  of  Spiritus  JEtheris  Nitrosi.  199 
magnified  300  times,  earth-nut  meal  is  readily  distinguished  ;  it  is 
seen  as  ring-shaped  depressions.  Other  substances  than  earth-nut 
meal  can  only  be  detected  by  special  methods. 
A  METHOD  FOR  PRESERVING  SPIRITUS  yETHERIS 
NITROSI.1 
By  A.  Meldrum. 
With  the  object  of  ascertaining  the  effects  of  light  and  heat  on 
the  composition  of  the  spirit,  and  whether  the  addition  of  glycerin 
would  have  any  influence,  beneficial  or  otherwise,  on  the  chemical 
changes  which  took  place  during  the  storage  of  it,  the  writer  had 
made  a  number  of  experiments.  A  strong  spirit  of  nitrous  ether 
was  made  by  the  pharmacopoeial  process.  One  part  of  it  was 
diluted  with  rectified  spirit,  as  directed  in  the  Pharmacopoeia ;  a 
second  part  with  rectified  spirit  and  glycerin,  so  that  the  finished  pro- 
duct contained  5  per  cent,  by  volume  of  glycerin  ;  and  a  third  part 
with  rectified  spirit  and  glycerin,  so  that  the  finished  product  con- 
tained 10  per  cent.,  of  the  latter.  The  various  samples  were  exposed 
to  different  temperatures  and  degrees  of  light  for  a  month,  and  then 
examined  for  NO  gas  by  Allen's  process,  for  aldehyde  by  Thresh's 
method,  for  free  nitrous  acid,  for  free  acetic  acid,  and  for  total  free  acid- 
ity— the  last  three  having  been  examined  by  the  method  described  by 
Mr.  Peter  MacEwan,  but  substituting  alcoholic  for  aqueous  solution 
of  soda.  To  eliminate  the  influence  of  light  when  the  effect  of 
temperature  was  registered,  three  sets  of  samples  were  kept  in  the 
dark,  one  at  a  temperature  averaging  3 50  F.,  another  at  temperature 
550  to  6o°,  and  a  third  at  from  70°to75°.  To  eliminate  the 
influence  of  temperature  when  the  results  of  exposure  to  light  were 
wanted,  one  set  was  kept  in  the  dark,  a  second  was  exposed  to 
diffuse  daylight,  and  a  third  to  direct  daylight,  the  temperature  in 
every  case  having  been  the  same,  viz :  from  550  to  6o°.  The 
results,  which  were  detailed  in  tabulated  form,  showed  that  the  effect 
of  increased  temperature  tended  to  cause,  first,  loss  of  ethyl  nitrite  ; 
second,  slight  diminution  of  the  aldehyde ;  third,  increase  of  free 
nitrous  acid;  fourth,  increase  of  acetic  acid;  and,  fifth,  consequent 
1  Chemist  and  Druggist,  February  18,  1893.  Abstract  of  a  paper  read  at 
Edinburgh,  February  15,  before  the  North  British  Branch  of  the  Pharmaceuti- 
cal Society. 
