408  NITRATE  OF  AMMONIA  AND  NITROUS  OXIDE. 
the  solution.  From  the  sample  to  which  I  have  already  referred, 
I  obtained  in  this  way  11  per  cent,  of  phosphate  of  lime ;  and 
from  another  sample,  which  came  from  a  different  source,  I  have 
more  recently  obtained  no  less  than  40  per  cent,  of  the  same 
adulterant. 
I  have  reason  to  believe  that  both  these  samples  were  of  foreign 
manufacture. — -Land.  Pharm.  Jo  urn.,  August,  1868. 
ON  NITRATE  OF  AMMONIA  AND  NITROUS  OXIDE. 
[From  White's  Dental  Materia  Medica,  Phila.,  1868.J 
Nitrous  oxide  for  anaesthetical  purposes  has  come  into  such 
general  use,  that  information  is  constantly  asked  in  reference  to 
its  properties  ;  the  materials  used  in  its  manufacture  ;  the  process 
of  generating  it ;  how  to  determine  the  purity  of  the  nitrate,  and 
of  the  gas  when  made,  etc. 
As  found  in  commerce,  nitrate  of  ammonia  is  crystallized, 
granulated,  and  fused.  The  fused  salt  is  made  by  melting  down 
the  crystals,  and  allowing  them  to  solidify  into  a  compact  mass 
on  cooling.  The  granulated  is  made  by  evaporating  the  solution 
to  such  a  density  that  it  would  solidify  on  cooling,  then  reducing 
the  heat  and  stirring  the  mass  until  it  cools. 
The  three  varieties  are  all  more  or  less  deliquescent,  and 
should  be  kept  in  a  dry  place,  excluded  from  the  air. 
The  fused  is  generally  preferred,  because  the  amount  of  gas 
given  off  by  equal  weight  of  the  three  varieties  is  somewhat  in 
favor  of  the  fused  and  granulated,  and  the  latter  is  objected  to 
by  some  on  account  of  its  greater  liability  to  absorb  moisture  and 
gain  weight  by  exposure  to  the  air.  If  pure,  when  heated  on 
platinum  foil  the  nitrate  should  volatilize  completely.  A  residue 
of  any  considerable  amount  would  indicate  the  presence  of  some 
non-volatile  salt — probably  nitrate  of  potash  or  soda.  A  solution 
of  nitrate  of  ammonia  should  not  afford  a  precipitate  on  addition 
of  a  few  drops  of  chloride  of  barium,  which  would  indicate  sul- 
phuric acid ;  nor  on  the  addition  of  a  few  drops  of  a  solution  of 
nitrate  of  silver,  which  would  indicate  the  presence  of  chlorine. 
Sulphates  and  chlorides  are  almost  always  present  in  commer- 
