282  Amy  I  Nitrite  and  Nitrous  Ether. 
Am.  Jour.  Pharm. 
June,  1898. 
If  the  specific  gravity  of  the  sample  is  assumed  to  be  0-84,  which 
is  approximately  correct  in  most  cases,  the  calculation  can  be  short- 
ened by  simply  multiplying  the  number  of  cubic  centimeters  of  J? 
silver  nitrate  required  by  0  5 36.  In  this  case  it  is  7-45  X  0-536  — 
4-0  per  cent.  This  factor  can  be  employed  only  when  5  c.c.  of 
spirit  are  taken  for  assay.  If  it  is  desired  to  avoid  calculation 
entirely,  2-7  c.c.  of  spirit  and  half  the  quantities  of  the  reagents 
N 
may  be  taken,  in  which  case  each  cubic  centimeter  of  —  silver  nitrate 
10 
indicates  1  per  cent,  of  ethyl  nitrite. 
Concentrated  nitrous  ether  may  be  assayed  by  diluting  with  alco- 
hol in  definite  proportions,  or  in  accordance  with  the  directions  on 
the  label,  and  proceeding  as  in  the  assay  of  spirit  of  nitrous  ether. 
Valuation  of  Amy  I  Nitrite.— Partially  fill  a  100  c.c.  graduated  flask 
with  alcohol,  insert  the  stopper  and  weigh.  Add  five  to  six  grammes 
of  the  amyl  nitrite  to  be  tested  and  weigh  again.  Fill  the  flask  to 
the  100  c.c.  mark  with  alcohol  and  mix  thoroughly  by  shaking. 
Then  proceed  in  the  same  manner  as  directed  for  spirit  of  nitrous 
ether,  using  20  c.c.  of  distilled  water,  10  c.c.  of  the  saturated  solution 
of  potassium  chlorate,  10  c.c.  of  the  alcoholic  dilution  of  amyl  nitrate 
N 
and  10  c.c.  of  dilute  nitric  acid.    Also  use  20  c.c.  of  _  silver  nitrate 
10 
and  titrate  the  excess  as  directed  above,  observing  the  same  precau- 
tions. The  calculation  of  results  is  made  as  explained  by  the  follow- 
ing example :  Assuming  the  alcoholic  dilution  to  contain  6-037 
grammes  of  the  sample  in  100  c.c,  the  10  c.c.  taken  for  assay  contain 
N 
0-6037  gramme.  If  in  titrating  the  excess  of  silver,  5-45  c.c.  of  ^_ 
potassium  sulphocyanate  are  required,  (20  —  5-45  =)  14-55  cc-  °^ 
—  silver  nitrate,  each  cubic  centimeter  equivalent  to  0-0351  gramme 
10 
of  amyl  nitrite,  have  been  consumed  in  precipitating  the  chloride 
formed  in  the  reaction.    The  calculation  then  is 
14-55  X  00351  X  100  =  g4.6  cent 
0-6037 
In  the  application  of  this  method  care  must  be  taken  either  to  use 
pure  reagents  or  to  make  allowance  for  the  interfering  impurities 
