186  Notices  respecting  New  Boohs. 
low.  since  the  activity  of  the  radium,  as  given  above,  pro- 
bably does  not  include  that  due  to  the  slowly  changing 
products  radium  E  and  radium  F.  On  the  other  hand,  the 
estimate  of  4*25  X  10G,  made  by  the  first  method,  may  be  too 
high  owing  to  the  presence  of  one  or  more  other  radioactive 
bodies  intermediate  between  uranium  and  radium,  in  the 
series  o£  uranium  transformation  products.  The  existence  of 
such  intermediate  substances  has  been  suggested  by  Soddy  * 
in  explanation  of  the  slowness  with  which  radium  emanation 
is  produced  by  uranium.  Possibly  emanium  and  its  product  f 
actinium  are  among  these  supposed  intermediate  substances. 
XV.  Notices  respecting  New  Books. 
Transactions  of  tlie  International  Electrical  Congress,  St.  Louis,  1004. 
Published  under  the  care  of  the  General  Secretary  and  the 
Treasurer.  Printed  bv  J.  B.  Lyon  Company,  Albany,  1N".T., 
1905.     Vol.  I.  pp.  879';  Vol.  II.  pp.  984  ;  Vol.  III.  pp.  980. 
^HESE  handsome  volumes,  embodying  the  work  of  the  Inter- 
-*-  national  Electrical  Congress  at  St.  Louis,  will  form  a  valuable 
reference  book  alike  for  the  pure  physicist  and  the  electrical 
engineer.  The  scope  of  the  Congress's  activity  was  a  very  wide 
one,  as  may  be  gathered  from  the  following  list  of  Sections : — 
(A)  General  theory  (including  mathematical  and  experimental 
papers) :  (B)  General  applications ;  (C)  Electro-chemistry ; 
(D)  Electric  power  transmission  ;  (E)  Electric  lighting  and  distri- 
bution ;  (F)  Electric  transportation  ;  (G)  Electric  communication  ; 
(11)  Electrotherapeutics.  As  might  have  been  expected,  the 
papers  contributed  vary  a  good  deal  as  regards  both  length  and 
importance,  some  being  little  better  than  brief  general  notes, 
while  others  are  very  thorough  investigations  of  permanent  value 
to  the  scientific  worker  and  engineer.  Vol.  L,  which  contains  the 
papers  contributed  to  Sections  A  and  B,  should  strongly  appeal  to 
the  pure  physicist.  It  opens  with  a  highly  interesting  paper  by 
Prof.  H.  T.  Barnes  on  the  Mechanical  Equivalent  of  Heat,  and 
contains  a  large  number  of  contributions  to  the  ionic  theory  by 
leading  workers  in  this  branch  of  science.  The  papers  in  Section  B 
are  rather  more  technical,  there  being,  in  addition  to  some  which 
deal  with  hysteresis,  magnetic  viscosity,  electrolytic  rectifiers  <fcc, 
others  devoted  to  alternators,  induction  motors  and  single-phase 
commutator  motors.  Volume  II.  contains  the  Transactions  of 
Sections  C,  D,  and  E.     In  Section  C,  we  have  valuable  papers  on 
*  Loc.  cit. 
t  Marckwaldj  Ber.  d.  chem.  Ges.  xxxviii.  p.  2264  (1905). 
