570 
Reviews. 
{Am,  Jour.  Pharm. 
I  November,  1901. 
of  certain  substances ;"  their  retardation  of  plant  growth  is  consid- 
ered but  no  mention  is  made  of  the  fact  that  these  so-called  toxic 
substances  may  not  only  possess  an  inhibitory  effect  on  plant  growth 
in  one  degree  of  concentration,  but  according  to  the  varying  strength 
of  the  solution  they  may  simply  retard  development  temporarily,  or 
may  stimulate  activity  or  produce  no  effect  whatsoever. 
The  Absolute  Atomic  Weights  of  the  Chemical  Elements, 
established  upon  the  analyses  of  the  chemists  of  the  nineteenth  cen- 
tury and  demonstrating  the  unity  of  matter ;  presented  in  simple 
language  to  the  general  scientific  public.  By  Gustavus  Detlef  Hin- 
richs.    St.  Louis,  Mo. :  C.  G.  Hinrichs. 
This  work  is  divided  into  four  parts,  in  which  are  considered:  (i) 
The  errors  of  precision  in  atomic  weight  determinations  ;  (2)  the 
absolute  atomic  weight  of  ten  leading  elements  ;  (3)  the  absolute 
atomic  weights  of  boron  and  nitrogen ;  (4)  tabular  view  of  the 
atomic  weight  analyses  of  the  nineteenth  century. 
The  author  shows  the  liability  to  error  in  taking  the  mean  ot  a 
series  of  determinations  as  the  basis  of  arriving  at  the  true  atomic 
weight  of  the  elements.  In  the  note  on  the  atomic  weight  of 
arsenic  (see  this  Journal,  p.  497)  the  author  has  shown  the  precision 
of  his  method. 
The  diamond  has  been  taken  as  the  standard  of  matter  for  all 
atomic  weight  determinations,  and  the  methods  of  direct  oxidation 
and  reduction  of  the  metals  as  employed  by  Berzelius  and  his  pupils 
are  considered  among  the  best  methods  for  atomic  weight  deter- 
minations. The  labors  of  the  author  are  deserving  of  careful  con- 
sideration. It  is  unfortunate,  however,  that  he  has  not  been 
content  simply  to  discuss  the  labors  of  Stas,  Clarke  and  others. 
While  the  language  used  in  regard  to  various  chemists  may  not 
vitiate  the  facts,  it  will,  however,  tend  to  prevent  their  dissemination 
as  easily  as  otherwise  might  have  been  the  case. 
Die  Serum-,  Bakterientoxin-  und  Organ-  Praparate.  Ihre 
Darstellung,  Wirkungsweise  und  Anwendung.  Fur  Chemiker, 
Apotheker,  Aerzte,  Bakteriologen,  etc.,  dargestellt  von  Dr.  Max  v. 
Waldheim.    Wien,  Pest,  Leipzig  :  A.  Hartleben's  Verlag. 
The  remarkable  discoveries  in  the  past  ten  years  in  bacteriological, 
physiological  and  chemical  researches  under  the  leadership  of  Pasteur, 
Koch,  Behring  and  others,  has  given  us  in  blood  serums,  bacteria 
