Am.  Jour.  Pharm. 
July,  1880. 
A  Correction. 
339 
ing  drops  usually  less  than  one-half  the  size  of  drops  of  water.  Solu- 
tions, syrups  and  dilute  acids  afford  drops  but  slightly  smaller  than 
water,  excepting  solution  of  nitrate  of  mercury  and  syrups  containing 
or  made  from  fluid  extracts.  Acids,  wines,  fixed  oils,  vinegars  and 
mixtures  give,  in  most  cases,  drops  of  more  than  one-half  the  size  of 
water,  about  two-thirds. 
In  the  drop  measurement  of  the  various  classes  of  preparations 
in  the  United  States  Pharmacopoeia  there  was  found  a  noticeable  uni- 
formity ;  amongst  the  officinal  wines  the  extremes  showed  a  difference 
of  but  fourteen  drops  in  the  fluidrachm.  The  fluid  extracts  and  tinc- 
tures, much  larger  classes,  show,  naturally,  a  greater  range,  but  withal 
a  regularity  sufficient  to  suggest  the  addition  of  a  list  giving  the  aver- 
age size  of  drops  of  each  class.  But  four  exceptions  were  found  neces- 
sary ;  these  are  appended  to  the  tabular  list.  It  will  be  observed  that 
the  liquids  yielding  smallest  drop  are  placed  first  in  order  in  the  follow- 
ing table : 
Average  Size  of  Drops  of  Classes  of  U.  S.  P.  Preparations. 
Average  Average 
Class.  No.  of  drops                              Class.  No  of  drops 
in  foi.  ni  f5i. 
Ether  and  Stronger,   .  .174  Mixtures,         .              .  ,89 
Fluid  extracts,    .  .           141  Vinegars,  ...  77 
Spirits,       .              .  .    141  Syrups  not  containing  fluid  extracts,  69 
Tinctures,          .  .           136  Solutions  (i  exception),  .  66 
Volatile  oils,              .  .     131  Diluted  acids,   .               .  .61 
Oleo-resins,        .  .  124  Exceptions. 
Acids  (3  exceptions),  .    123  Solution  nitrate  of  mercury,  .  131 
Wines,               .  .           106  Nitromuriatic  acid,  .  .  76 
Fixed  oils,                 .  .    103  Muriatic  acid,  .              .  .70 
Syrups  containing  fluid  extracts,      97  Sulphurous  acid,      .  .  59 
A  CORRECTION. 
In  my  article  in  the  Journal  for  April,  on  "  Tests  for  Arsenic,"  I 
expressed  the  opinion  that  the  subnitrate  of  bismuth  might  have  con- 
tained arsenic.  This  is  a  mistake,  and  I  hasten  to  correct  it,  as  the 
chemist.  Prof.  Howard,  testified  in  court  that  he  had  examined  a  sample 
of  it  and  it  contained  none.  As  my  attention  was  called  to  it  by  the 
professor,  I  now  recollect  that  such  was  his  testimony  in  court,  and 
in  justice  to  him  I  make  the  correction,  as  I  have  the  highest  con- 
fidence in  his  ability  and  thoroughness  as  an  analytical  chemist. 
Phil.  Hoglan. 
Ne^comerstouon^  O.,  May  24th,  1880. 
