IRON  ALUM. 
159 
has  often  proved  a  means  of  inducing  a  habit  of  dram-drinking, 
which  prevails  even  among  respectable  females  to  a  far  greater 
extent  than  is  usually  supposed." — Transactions  of  the  Ohio  State 
Medical  Society. 
IRON  ALUM. 
The  Curator,  Mr.  Greaves,  drew  the  attention  of  the  meeting  to 
a  specimen  of  Iron  Alum,  which  had  been  sent  by  Mr.  Lindsey 
Blyth,  of  St.  Mary's  Hospital,  accompanied  by  a  note,  which  was 
read.    The  object  of  Mr.  Blyth's  communication  was,  to  describe 
the  composition  of  the  salt  which  has  rec°-tly  been  prescribed  by 
some  of  the  medical  officers  attached  to  St.  Mary's  Hospital,  under 
the  name  of  Iron  Alum,  to  explain  the  circumstances  under  which 
it  was  first  brought  under  their  notice,  and  the  process  which  had 
been  adopted  at  the  hospital  for  making  it.    The  salt  first  used 
at  St.  Mary's  Hospital  was  part  of  a  sample  obtained  by  Mr.  Da- 
venport as  a  bye-product  in  the  preparation  of  some  ferruginous 
compounds.    It  was  found   by  Dr.  Tyler  Smith  to  be  a  more 
powerful  astringent  than  common  alum,  and  not  liable  to  produce 
the  stimulating  effects  of  other  salts  of  iron.    The  salt  obtained 
from  Mr.  Davenport  consisted  of  sulphate  of  peroxide  of  iron  and 
sulphate  of  ammonia,  having  the  constitution  and  crystalline 
form  of  common   alum.      Some   of  the   salt   had  been  pre- 
pared by  Messrs.  Ho'pkin  and  Williams,  and  it  had  subsequent- 
ly been  made  at  the  hospital,  both  with  potash  and  ammonia.  It 
was  well  known  that  the  name  Alum  had  for  some  time  past  been 
applied  by  Chemists,  as  a  generic  designation,  to  a  long  series  of 
salts  which  coincided  with  common  alum  in  constitution  and  form. 
Thus,  common  alum,  which  is  usually  viewed  as  a  double  salt, 
consisting  of  sulphate  of  alumina  and  sulphate  of  potash,  being 
taken  as  the  type,  iron  alum  is  formed  by  substituting  peroxide  of 
iron  for  the  alumina.    And  as,  in  common  alum,  the  potash  may 
be  replaced  by  ammonia  or  soda  as  well  as  by  many  other  protox- 
ides, so  a  similar  replacement  may  be  effected  in  iron  alum  with- 
out altering  the  type.  Mr.  Blyth  directed  the  attention  of  those 
who  had  not  particularly  studied  this  subject,  to  a  table  represent- 
ing the  composition  of  some  of  the  salts  which  have  been  de- 
scribed under  the  generic  name  of  alum. 
