Am'juiyr;i894arm-}    Note  on  Wilbur  S.  Scovilles  Paper.  329 
NOTE  ON  WILBUR  S.  SCOVILLE'S  PAPER  «  CHANGE  OF 
VOLUME  WHEN  LIQUIDS  OF  DIFFERENT 
DENSITIES  ARE  MIXED." 
By  Louis  Kahlenberg. 
My  attention  has  recently  been  called  to  the  above-mentioned 
paper,  which  appeared  in  the  minutes  of  the  meeting  of  the  Ameri- 
can Pharmaceutical  Association  (p.  131),  held  at  Chicago,  August 
14  to  20,  1893.  In  his  article,  the  author  gives  a  list  of  thirty-four 
experiments  illustrating  that  changes  of  volume  generally  occur 
when  liquids  of  different  densities  are  mixed.  He  mentions  the 
fact  that  slight  changes  in  temperature  also  take  place,  but  states 
that  the  object  of  his  paper  is  11  only  to  call  attention  to  the  changes 
in  volume  which  occur,  to  show  how  nearly  universal  this  change 
is,  and  to  demonstrate  that  it  is  of  sufficient  extent  to  render  void 
the  use  of  specific  gravity  rules,*  in  most  cases,  for  anything  except 
approximate  results." 
If  Mr.  Scoville  will  take  the  pains  to  consult  the  chapter  on  solu- 
tions in  Ostwald's  Lehrbuch  der  Allgemeinen  Chemie  (2te  Aufl.) 
Band  I,  p.  636,  he  will  find  that  the  fact  that  he  seeks  to  point  out 
by  his  few  isolated  experiments  has  long  been  known,  and  that 
there  are  generally  not  only  changes  in  volume  when  two  liquids 
of  different  densities  are  mixed,  but  also  changes  in  the  optical, 
thermal  and  other  properties.  Professor  Ostwald  treats  the  espe- 
cially interesting  case  of  salt  solutions  in  a  separate  chapter  of  the 
volume  already  mentioned  (see  pages  782  to  791).  References  to 
numerous  memoirs  on  this  subject  will  also  be  found  in  the  localities 
cited. 
Chemical  Laboratory,  University  of  Wisconsin, 
June  4,  1894. 
The  extermination  of  our  native  flora  by  forest  fires  is  often  more  complete 
than  that  caused  by  plant  collectors,  who  miss  small  seedlings  and  do  not 
remove  all  the  roots  of  plants.  But  a  fire,  especially  when  it  attacks  the 
habitat  of  plants  such  as  Cypripeditcms,  imbedded  in  sphagnum  moss  and 
covered  with  old  leaves,  completely  destroys  them,  root  and  branch. 
*  Meaning  the  ordinary  rule  that  applies  closely  only  in  those  few  cases 
where  the  volume  of  the  mixture  is  exactly  equal  to  the  sum  of  the  volumes 
of  the  liquids  mixed. 
