548 
NOTES  ON  FROTH. 
stated  by  Dr.  Garrod  ;  and  that  it  had  been  distinctly  stated  by 
Geigar,  on  the  authority  of  Liebig,  that  atropa,  stramonium,  and 
hyoscyamia  were  decomposed  by  fixed  alkalies,  and  that  on  the  ap- 
plication of  heat  the  decomposition  was  more  rapidly  effected. 
From  having  read  the  statement  of  Leibig  some  twelve  or  thirteen 
years  ago,  he  had  never  since  ordered  fixed  alkalies  in  combination 
with  either  of  those  preparations. 
Dr.  Garrod  said  he  had  enumerated  in  his  paper  the  works  in 
which  the  statement  had  been  made,  that  alkalies  had  the  power  of 
destroying  the  active  principles  of  henbane.  He  claimed  no  origi- 
nality in  the  matter,  but  simply  the  merit  of  having  brought  the 
subject  prominently  forward,  at  a  time  when,  notwithstanding  the 
statements  of  several  authors,  medical  men  were  constantly  in  the 
habit  of  prescribing  medicines  which  had  the  power  of  completely 
neutralizing  each  other. — London  Pharm.  Jour.,  Sept.  1858,  from 
Medical  Times  and  Gazette. 
NOTES  ON  FROTH. 
By  Dr.  Gladstone,  F.  R.  S. 
All  liquids,  when  shaken  up  with  air,  form  bubbles;  but  some 
allow  these  bubbles  to  break  and  disappear  the  moment  they  are 
at  rest,  while  others  give  rise  to  a  more  or  less  permanent  froth. 
This  difference  among  liquids  appears  to  be  of  a  specific  charac- 
ter, and  cannot  as  yet  be  shown  to  be  dependent  on  any  other 
quality. 
As  a  general  rule,  aqueous  solutions  of  organic  bodies  are 
more  disposed  to  froth.  Beer  is  a  familiar  instance.  In  this 
case,  the  formation  of  the  froth  is  originally  due  in  a  great  mea- 
sure to  the  rising  of  carbonic  acid  gas  through  the  liquid ;  but 
its  permanence  is  totally  independent  of  that,  or  indeed  of  any 
dissolved  gas.  This  was  proved  by  subjecting  some  beer  to  ex- 
haustion by  an  air-pump,  till  every  trace  of  the  carbonic  acid 
and  air  it  contained  was  removed,  withdrawing  it  from  the  va- 
cuum, and  shaking  it  immediately,  when  a  fine  froth  was  pro- 
duced which  was  as  persistent,  or  nearly  so,  as  if  the  beer  had 
continued  brisk. 
Solutions  of  the  acetates  are  peculiarly  disposed  to  produce 
a  permanent  froth.    To  such  an  extent  is  this  the  case,  that,  in 
