Am.  Jour.  Pharm.  ) 
July,  1877.  J 
Spirit  of  Nitrous  Ether. 
367 
agitated  with  twice  its  volume  of  a  concentrated  solution  of  chloride 
of  calcium,  a  certain  portion  of  ethereal  liquid  will  rise  to  the  surface 
if  the  spirit  contains  over  eight  per  cent,  of  nitrous  ether.  Prof.  Red- 
wood states  that  under  these  circumstances  eight  per  cent,  of  nitrous 
ether  will  remain  in  solution,  but,  as  I  have  already  had  occasion  to 
mention,  he  evidently  means  crude  nitrous  ether,  i.  e.,  such  ether  as  will 
rise  to  the  surface  of  the  above  mentioned  mixture  ;  and  that  the 
separated  ether  is  not  absolute  nitrous  ether  I  have  determined  by  the 
specific  gravities  of  several  samples,  separated  by  the  method  of  the 
"British  Pharmacopoeia,"  which  ranged  between  8*878  and  0*890. 1 
Now,  while  it  has  been  proved  that  the  spirit  of  nitrous  ether  of  the 
U.  S.  P.  can  not  contain  five  per  cent,  of  absolute  nitrous  ether,  it 
seemed  more  than  probable  that  it  might  contain  five  per  cent,  of  such 
crude  ether  as  is  separable  under  the  above-named  conditions  ;  and 
that  this  is  so,  is  readily  shown  by  the  following  results,  obtained  with 
a  portion  of  the  "concentrated  spirit" — the  15  fluidounces  of 
distillate,  diluted  to  32  fluidounces  with  stronger  alcohol  : 
1.  It  was  calculated  that  if  the  spirit  of  nitrous  ether  contained  five 
per  cent,  of  such  crude  ether,  the  concentrated  spirit  should  contain 
16*82  per  cent.  On  agitating  10  cc.  of  the  concentrated  spirit  with 
20  cc.  of  saturated  solution  of  chloride  of  calcium,  B.  P.,  0*85  cc.  of 
ethereal  liquid  separated,  indicating  16*5  per  cent,  of  crude  ether. 
2.  If  in  the  above  experiment  eight  per  cent,  of  crude  ether 
1  In  the  "United  States  Dispensatory,"  13th  ed  ,  (1870),  p.  1405,  after  quoting 
from  the  "British  Pharmacopoeia"  the  volumetric  test  for  determining  the  strength 
of  its  spirit  of  nitrous  ether,  the  following  remarkable  statement  is  made  :  "  This 
indicates  a  strength  considerably  less  than  that  of  the  U.  S.  spirit,"  and  on  page 
1447  of  the  recent  (14th)  edition  of  the  same  work,  this  statement  is  repeated.  A 
careful  revision  of  the  work  should  have  prevented  the  repetition  of  an  error,  which 
a  simple  comparison  of  the  two  processes  would  have  made  evident,  and  which  is 
all  the  more  serious  because  the  work  is  used  as  a  text-book  by  beginners. 
But  the  most  astonishing  error,  in  this  connection,  will  be  found  in  "  Parrish's 
Treatise  on  Pharmacy,"  4th  ed.  (1874),  p.  373.  It  is  here  stated  :  "  The  strength 
of  this  spirit"  (referring  to  the  product  of  the  U.  S.  P.)  "may  be  ascertained  by 
putting  a  small  quantity  in  a  test-tube,  mixing  with  it  double  its  bulk  of  a  saturated 
solution  of  chloride  of  calcium,  and  shaking  together.  If  one  per  cent  of  ether 
rises  to  the  surface,  it  will  be  evidence  that  it  contained  five  per  cent ,  as  but  one- 
fifth  of  the  ether  is  set  free  by  this  experiment."  The  revisor  of  this  work  evidently 
failed  to  give  this  subject  that  careful  attention,  which  a  work,  designed  for 
students,  imperatively  demands. 
