IMPURITY  OF  BROMIDE  OF  POTASSIUM.  77 
to  the  stream  from  a  fire-engine  worked  by  six  strong  men,  from 
a  distance  of  15  yards,  allowed  no  water  to  pass,  except  where 
the  stuff  was  in  contact  with  the  frame  and  was  compressed  upon 
it  by  the  violence  of  the  jet,  but  the  transpiration  from  the  skin 
appears  to  destroy  the  impermeability,  so  that  it  is  probably  ap- 
plicable only  to  exterior  clothing ;  finally,  that  there  is  every 
probability  that  it  is  lasting,  as  appears  from  the  certificates. 
M.  Balard  himself  testifies  that  an  overcoat  worn  by  him  for  five 
months,  which  had  been  beaten  and  rubbed  and  subjected  to  all 
the  ordinary  usage  of  overcoats,  remained  perfectly  impermeable. 
Oloths  prepared  in  this  way  are  said  to  be  softer  to  the  touch, 
warmer,  absorbing  less  moisture,  drying  more  quickly,  and  there- 
fore more  durable. 
It  would  appear,  therefore,  that  this  process,  which  is  cheap 
and  easily  applicable,  even  after  articles  are  made  up,  is  well 
worth  experimenting  upon. — London  Qkem.  Gfaz.,  Nov.  2, 1857, 
from  Journ.  of  the  Franklin  Inst,  for  April,  1857. 
ON  THE  IMPUBXTY  OF  BROMIDE  OF  POTASSIUM. 
By  A.  B.  Garrod,  M.  D., 
Professor  of  Materia  Medica  and  Therapeutics  at  University  College,  London. 
Bromide  of  potassium,  on  account  of  the  encomiums  passed 
upon  it  by  the  late  Dr.  T.  Williams,  was  introduced  into  the  Lon- 
don Pharmacopoeia  of  1836;  it  had  been  found  useful  by  the 
above-mentioned  physician,  more  especially  in  diseases  of  the 
spleen,  in  cases  where  this  organ  had  become  hypertrophied  or 
enlarged.  However,  during  the  interval  which  elapsed  between 
the  publication  of  the  Pharmacopoeias  of  1836  and  1851,  its  ad- 
vocate passed  from  among  us,  the  drug  was  not  very  extensively 
employed,  and  it  was  omitted  from  the  College  list  of  the  Materia 
Medica.  This,  I  think,  is  to  be  deplored,  for  either  it  had  not 
adequate  claims  to  be  admitted  in  1836,  or  sufficient  time  was 
not  allowed  for  its  remedial  powers  to  be  fully  and  properly  in- 
vestigated. Within  the  last  few  years  it  has  been  much  more 
extensively  employed,  both  in  this  country  and  in  France,  and 
for  some  lengthened  period — certainly  since  1851 — I  have  given 
it  rather  largely,  both  in  private  and  hospital  practice.  Bromide 
of  potassium  produces  many  peculiar  physiological  effects,  and 
