242 
Book  Reviews. 
$  Am.  Jour.  Pharm. 
(     March,  1921. 
element.  Then  follow  the  laws  of  chemical  proportions — the  law  of 
Proust,  of  Gay-Lussac,  and  of  Dalton.  A  chapter  is  devoted  to  the 
atomic  theory,  and  another  to  the  general  characters  and  interrela- 
tions of  the  elements — this  including  some  of  the  more  recent  con- 
tributions to  chemical  theory,  particularly  along  those  lines  which 
in  American  chemical  literature  are  grouped  under  the  general  cap- 
tion subatomic  phenomena.  Next  follow  the  theories  of  solutions, 
a  most  interesting  presentation,  involving  a  discussion  of  dissocia- 
tion, or  hydrolysis,  of  hydrates  in  solutions  and  of  solid  solutions; 
also  a  rather  extensive  discussion  of  chemical  affinity,  touching  upon 
speed  of  reactions,  the  law  of  mass  action,  the  phase-rule,  catalysis — ■ 
to  mention  but  a  few  of  the  subjects  of  vital  interest  which  make 
up  this  important  chapter.  Then  follows  a  brief  appendix,  dealing 
with  crystal  structure.  And  finally,  there  is  a  contribution  by  the 
translator  on  the  subject  of  Hydrogen-ion  Concentration,  a  develop- 
ment of  the  theory  of  ionization  which  has  in  recent  years  been 
applied  in  practical  analysis  and  has  made  possible  some  very  deli- 
cate quantitative  work,  particularly  in  biochemistry. 
In  a  book  of  limited  size  one  cannot  expect  comprehensive 
treatment  of  all  chemical  theories ;  but  the  selection  of  material — * 
as  viewed  from  the  standpoint  of  American  needs — is  in  the  main 
a  happy  one.  We  miss,  however,  the  generalizations  pertaining  to 
the  colloidal  state  of  matter,  a  subject  of  great  interest  and  of 
practical  importance.  To  be  sure,  our  knowledge  of  colloids  is  in 
the  main  physical  knowledge  rather  than  chemical  knowledge.  But 
the  same  may  be  said  also  of  much  else  dealt  with  in  connection 
with  chemical  theories. 
The  phraseology  of  Dr.  Leffman's  translation  is  precise  and 
lucid.  His  long  experience  as  a  teacher,  and  as  a  lecturer  on  chemi- 
cal subjects,  not  only  to  academic  classes,  but  also  to  mixed  audi- 
ences, stands  him  in  good  stead  in  presenting  the  subject  matter 
clearly.  This  is  done,  however,  without  any  effort  to  avoid  the 
technical  terms  of  science.  The  principles  of  chemistry,  it  must  be 
admitted,  are  inherently  difficult  of  transmission  from  mind  to  mind ; 
the  process  is  not  made  easier,  however,  when  it  is  attempted  to 
clothe  chemical  abstractions  in  colloquial  English — an  attempt  which 
usually  fails,  except  in  dealing  with  the  simpler  theories.  In  short, 
the  translation  is  admirable  in  that  a  French  text  book  has  been 
rendered  not  in  what  is  commonly  called  the  King's  English  or  the 
Queen's,  nor  in  that  of  the  kindergarten,  but  in  English  far  better 
