1 20 
Hydrobromic  Acid. 
i  Am.  Jour.  Pharm. 
(       Mar.,  1878. 
weight.  A  troyounce  of  it  contains  almost  exactly  400  minims 
(401  '48+),  and  the  fluidounce,  of  480  minims,  weighs  almost  exactly 
574  grains  (573*86+).  A  drachm  of  it,  therefore,  would  contain  50 
minims,  and  would  be  the  bromine  equivalent  of  30  grains  of  potassium 
bromide.  A  gram  of  the  acid  is  equal  to  12*86  minims,  and  therefore 
4  grams  would  be  51*44  minims,  equal  to  30*86  grains  of  the  potassium 
bromide,  a  very  large  sedative  dose. 
The  acid  is  not  very  easily  administered  in  full  doses  in  consequence 
of  the  large  dilution  necessary,  and  the  disagreeable  effect  of  "  setting 
the  teeth  on  edge."  A  dose  of  50  grains,  equal  to  41*66  minims,  and 
to  25  grains  of  potassium  bromide,  requires  not  less  than  8  fluidounces 
of  dilution,  and  the  dilution  must  contain  not  less  than  an  ounce  of 
sugar  or  two  ounces  of  syrup,  to  make  it  easily  drinkable.  This  will 
be  found  to  be  the  principal  drawback  to  the  use  of  the  acid,  unless  it 
shall  be  proved  to  be  effective  in  smaller  quantities  than  its  equivalence 
to  the  bromides  indicates.  And  this  effectiveness  in  much  smaller 
doses  is  not  only  probable,  but  almost  certain,  if  the  experience  of 
Fothergill  and  others  may  be  trusted,  since  they  give  it  in  doses  of  one- 
eighth  to  one-fourth  of  those  here  indicated  as  being  the  bromine 
equivalent  of  potassium  bromide.  That  is  to  say,  the  doses  advised 
by  those  who  appear  to  have  used  it  with  the  best  effects  are  equiva- 
lent to  about  6  to  8  grains  of  potassium  bromide.  This  published 
experience  would  make  the  average  dose  of  the  acid  here  described,  say 
about  12  to  16  grains,  or  the  bromine  equivalent  of  only  6  to  8  grains 
of  potassium  bromide.  In  the  very  limited  experience  of  physicians 
around  the  writer  these  doses  are  too  small,  and  20  to  30  grains,  equal 
to  10  to  15  grains  of  potassium  bromide  are  needed  for  a  prompt  seda- 
tive effect,  while  40  to  50  grain  doses  are  not  uncommon  ;  and  such 
doses  have  to  be  repeated  at  times  in  controlling  the  headache,  etc.,  of 
quinism.  Even  such  doses  require  a  dilution  of  2  to  4  fluidounces  of 
water  for  easy  administration. 
If  60  grains=50  minims  of  the  acid  here  described  be  added  to  1140 
grains  of  syrup  the  mixture  will  measure  2  fluidounces,  and  weigh 
(60+1140=)  1,200  grains.  Each  75  grains  of  this,  1  fluidrachm,  will 
contain  4  grains  nearly,  or  a  little  more  than  3  minims  of  the  acid  ;  and 
4  fluidrachms  of  this,  equal  to  1 5  grains  of  the  acid  when  diluted  with 
ice  water  to  2  to  4  fluidounces  makes  a  dose  which  is  easily  adminis- 
