438  Unguentum  Hydrargyri  Nitratis.  {^"seprissa""* 
A  conchinine  sulphate,  the  polarizing  plane  of  which  diverges  only 
30°  instead  of  31°,  contains  about  2  per  cent,  of  cinchonidine  sul- 
phate, as 
0-98  X  31  =  right,  30-38° 
0-02  X  14  =  left,  0-28° 
DifFerence  =  right,  30-10° 
A  cinchonine  sulphate  solution  which  is  contaminated  with  5  per 
cent,  of  cinchonidine  sulphate  is  very  easily  recognized  as 
0-95  X  31  right,  29-45° 
0-05  +  14  =  left,  0-70° 
DifFerence  =  right,  28-75° 
An  exhaustive  treatise  on  these  optical  observations,  by  Rozsnyay,. 
may  be  obtained  from  Drs.  Sterg  and  Keuter,  in  Homburg,  for  the 
small  sum  of  i  mark 
UNGUENTUM  HYDRARGYRI  NITRATIS. 
By  Charles  Wolf  Beichard,  Ph.G. 
From  an  Inaugural  Essay. 
The  author  made  a  series  of  experiments,  following  the  process  of 
the  Pharmacopoeia  for  1880,  but  using  different  kinds  of  fats.  76 
parts  of  the  fat  Avere  heated  to  70°C.,  when  7  parts  of  nitric  acid,  of 
the  proper  strength,  were  added  without  stirring,  but  with  continuing 
the  heat  as  long  as  a  moderate  effervescence  took  place ;  when  nearly 
cool,  the  warm  solution  of  7  parts  of  mercury  in  10  parts  of  nitric 
acid  was  added  and  stirred.  In  each  case  the  degree  or  absence  of 
effervescence,  change  of  color  and  other  changes  were  noted,  as  was 
also  the  color,  odor  and  consistence  of  the  preparation  as  soon  as  it  had 
become  cold,  about  an  hour  after  the  mercury  solution  had  been  added 
to  the  fat.  Similar  observations  were  afterwards  made  at  regular 
intervals.  The  fats  used  were  (1)  castor  oil,  (2)  neats'  foot  oil,  (3)  lin- 
seed oil,  (4)  vaseline,  (5)  cosmoline,  (6)  oleic  acid,  (7)  sweet  almond  oib 
(8)  lard  oil,  (9)  cotton  seed  oil,  (10)  lard,  (11)  lard  and  lard  oil,  (12) 
lard  and  cotton  seed  oil,  (13)  lard  oil  and  sweet  almond  oil,  (14)  castor 
oil  and  sweet  almond  oil,  and  (15)  butter.  The  author  has  tabulated 
his  results  as  follows  : 
