390  Spirit  of  Nitrous  Ether.  { Amj^r-18p85arm- 
It  would  be  tedious  to  describe  the  different  devices  that  have  been 
tried,  to  ensure,  if  possible,  an  accurate  result.  Suffice  it  to  say,  that 
as  an  inference  from  numerous  experiments,  the  following  method  was 
adopted  as  the  best : — Let  1  gram  of  iodide  of  potassium  be  dissolved 
in  10  cc.  of  water.  Then  add  20  cc.  of  rectified  spirit,  and  to  the 
solution  so  obtained  add  5  cc.  of  the  spirit  to  be  tested.  Now  pour  in 
5  cc.  dilute  sulphuric  acid,  and  allow  to  stand  for  an  hour,  then  titrate 
with  standard  thiosulphate.  The  operation  is  best  conducted  in  an 
eight  ounce  porcelain  basin.  The  following  are  some  of  the  results 
obtained  : — 
(occ  used  in  each  case  )  tV  Na2SoO,  EtNOo  EtN02(vol. ) 
{o  cc.  usea  m  eacn  case.)        solution.        grams.  percent. 
(a. )  10  per  cent,  (vol.)  solution  in  alcohol  59*5  cc.  =  '446  =  9'91 
(a.)  10  per  cent,  (vol.)  solution  in  alcohol  59.8  cc.  ==  "448  =  9*96 
(a.)  10  per  cent,  (vol.)  solution  in  alcohol  60*0  cc.  =  -450  =  10-00 
(6.)  Sple.  sp.  seth.  nit.  (recent)  26*5  cc.  =  '198  =  4-41 
(b.)  Sple.  sp.  seth.  nit.  (recent)  26*8  cc.  =  -201  =  4'46 
(e.)  Sple.  sp.  aeth.  nit.  (four  months)   23*5  cc.  =  -176  =  3*91 
(c.)  Sple.  sp.  a?th.  nit  (four  months)  24'0  cc.  =  "180  =  4*00 
Although  formerly  indicated,  it  may  again  be  noted  that  the  total 
nitrous  acid  is  given  as  ethyl  nitrite.  The  older  sample  contained 
much  more  free  acid  than  the  fresh  one.  The  method  employed  is 
evidently  only  approximate,  but  it  may  serve  until  something  better 
is  devised.  It  has,  at  any  rate,  the  advantage  of  requiring  only  such 
apparatus  and  reagents  as  are  in  common  use. 
Before  concluding,  I  would  venture  to  express  a  hope  that  the  com- 
pilers of  the  next  pharmacopoeia  will  fix  a  fair  standard  of  purity  for 
spirit  of  nitrous  ether,  so  that  no  departure  therefrom  will  be  allowed. 
We  sometimes  hear  the  fallacy  propounded,  that  an  inferior  prepara- 
tion must  be  excused,  because,  at  some  time  or  other,  it  has  been  pro- 
duced by  the  official  process.  This  is  an  entire  mistake.  Not  only 
must  the  official  process  be  followed,  but  it  must  be  so  conducted  as  to 
produce  a  right  result,  and  the  product  must  be  so  preserved  as  to  be 
of  proper  strength  when  required  for  use.  Yet,  as  the  pharmacopoeia 
requires  of  pharmacists  preparations  of  a  certain  degree  of  purity,  so 
pharmacists  require  of  the  pharmacopoeia  processes  and  tests  which  are 
reasonable. — Phar.  Jour,  and  Trans.,  April  12,  1884,  p.  819. 
A  Solution  of  Gallic  Acid  may  be  made  according  to  Dr.  F.  Long 
("Brit.  Med.  Jour.")  by  means  of  potassium  citrate.  Using  15  grains  of 
each,  the  mixture  will  dissolve  in  1  ounce  of  water. 
