36° 
Spirit  of  Nitrous  Ether. 
Am.  Jour.  Pharm, 
July,  1877. 
influence  on  the  reaction,  and  we  must,  therefore,  look  for  some  other 
cause  for  the  disparity  in  the  quantity  of  distillate.  This,  I  now  believe, 
to  be  owing  to  the  temperature  at  which  the  reaction  is  allowed  to  take 
place.  It  will  be  noticed  that  in  the  first  experimental  distillation  the 
heat  was  removed  when  the  thermometer  indicated  I52°F.  This  was 
done  because  the  reaction  was  quite  energetic,  as  evidenced  by  abundant 
frothy  ebullition,  and  because  the  "  Pharmacopoeia  "  directs  caution  in 
the  application  of  heat.  It  was  expected  that  the  temperature  would 
rise  spontaneously  to  near  the  limit  designed  by  the  "Pharmacopoeia;"' 
but  instead  it  rose  only  to  1650,  and  heat  had  subsequently  to  be  kept 
up  until  the  reaction  was  completed. 
It  the  second  experimental  distillation  the  heat  was  never  completely 
removed,  but  at  i6o°F.  the  gas  flame  heating  the  water-bath  was  turned 
low,  upon  which  the  temperature  rose  to  i68°F.,  and  there  remained 
stationary  for  some  time,  until  the  heat  was  again  increased.  Now  this 
slight  difference  in  the  heating  appears  to  have  had  a  remarkable  effect  in 
increasing  the  volume  of  distillate  ;  for,  while  by  the  first  heating  of  the 
first-  experimental  distillation  only  6-f  fluidounces  of  distillate  were 
obtained,  the  time  required  being  1  hour  and  12  minutes  ;  the  yield  of 
the  first  heating  of  the  second  experimental  distillation,  time  1  hour 
and  25  minutes,  was  about  10J  fluidounces.  Furthermore,  on  con- 
sulting the  directions  of  the  Br.  Ph.,  it  will  be  observed  that  the  distil- 
lation is  to  be  conducted  "  at  a  temperature  commencing  at  1700  and 
rising  to  1750,  but  not  exceeding  1800."  This  rather  unfortunately 
worded  direction,  can  only  mean  that  the  heat  is  to  be  applied  until  the 
temperature  reaches  1700,  and  that  it  is  then  to  be  checked,  when  it 
will  rise  spontaneously  to  1 75 0 .  As  Prof.  Redwood  undoubtedly 
readily  obtained  the  required  quantity  of  distillate,  any  disparity  in  the 
quantity  of  distillate  must  be  due  to  the  temperature  at  which  the  reac- 
tion is  allowed  to  take  place,  and  that  this  view  is  correct  is  further 
confirmed  by  the  results  of  Alfred  E.  Tanner,1  who,  following  the  pro- 
cess of  the  Br.  Ph.,  obtained  only  11  fluidounces  of  total  distillate;  but 
he  had  deviated  from  the  officinal  directions  by  distilling  "at  a  tem- 
perature commencing  at  1600,  and  rising  to  1750." 
Mr.  Tanner  found,  however,  that  the  11  fluidounces  of  distillate 
obtained  contained  the  full  officinal  quantity  of  nitrous  ether,  and  this 
1"Am,  Jour.  Phar.,"  Feb  ,  1871,  p.  82,  from  "  Phar.  Jour,  and  Trans." 
