46 
Reviews. 
f  Am.  Jour.  Pharm. 
I    January,  1900. 
fair  working  idea  of  the  essentials  of  practice.  The  development  of  the  micro- 
scope is  treated  historically,  and  is  supplemented  by  a  history  of  glass  manu- 
facture. This  order  appears  to  be  one  of  the  few  features  of  the  book  open  to 
criticism,  as  it  does  not  conduce  to  clearness.  The  allotment  of  space  to  the  dif- 
ferent subjects  treated  is  as  follows  :  Reflection  of  Light  has  ten  pages  ;  Refrac- 
tion, four  ;  Intensity,  two  ;  Simple  and  Compound  Microscopes,  treated  as  ma- 
chines, thirty-six  ;  Micrometers,  Camera  Lucida,  Micro-Photographic  Appara- 
tus and  Test-objects,  ten;  Optical  and  Working  Properties,  twelve  ;  Manipula- 
tion and  Care,  nine.  Then  follows  Part  II,  in  which  forty-five  pages  are  devoted 
to  Micro-technique.  A  concluding  chapter  of  twenty-five  pages,  which  might 
well  have  been  called  Part  III,  is  devoted  to  the  Normal  and  Abnormal  Eye. 
Here  the  author's  medical  training  is  put  to  good  service,  and  the  inexperienced 
microscopist  is  led  to  a  knowledge  of  the  results  of  defective  vision  upon  the 
use  of  the  microscope,  and  how  to  avoid  them.  Some  very  practical  sugges- 
tions concerning  the  care  of  the  eyes  are  added.  All  the  information  is  thor- 
oughly classified,  and  the  instruction  well  systematized.  The  language  is  clear, 
and  no  reader,  even  if  ignorant  of  the  high  abilities  of  the  author  as  a  histolo- 
gist,  could  fail  to  realize  that  he  writes  on  a  familiar  subject;  and  out  of  the  ful- 
ness of  personal  experience.  A  complete  index  of  five  double-column  pages 
completes  the  usefulness  of  this  thoroughly  commendable  volume. 
H.  H.  Rusby. 
Indicators  and  Test  Papers — their  Source,  Preparation,  Applica- 
tion and  Tests  for  Sensitiveness.  A  resume  of  the  current  facts  regard- 
ing the  action  and  application  of  the  indicators  and  test  papers  which  have  been 
proposed  from  time  to  time  and  are  in  present  use  in  chemical  manipulations, 
with  a  tabular  summary  of  the  applicaticn  of  indicators.  Designed  for  the  use 
of  chemists,  pharmacists  and  students.  By  Alfred  I.  Cohn,  Ph.G.  First  edi- 
tion. First  thousand.  1S99.  i2mo.  ix-249pages.  Cloth,  $2.  New  York  : 
John  Wiley  &  Sons. 
The  book  is  divided  into  four  parts.  Part  I,  the  introduction,  contains  general 
considerations,  correct  choice  of  indicators,  application  of  indicators,  action  of 
indicators  in  other  than  aqueous  liquids  and  the  theory  of  the  action  of  indica- 
tors. 
Part  II  contains,  in  alphabetical  order,  the  synonyms,  source,  preparation, 
properties  and  application  of  the  various  indicators  considered. 
Part  HI  deals  entirely  with  test  papers,  their  preparation  and  application. 
Part  IV  contains  tables  and  a  tabular  summary  of  the  principal  indicators. 
The  object  of  this  book  is  to  give  an  up-to-date  resume  of  the  various  sub- 
stances that  have  been  employed  as  indicators  in  one  form  or  another.  The 
number  of  indicators  considered  is  certainly  comprehensive,  but  the  author 
fails  in  a  number  of  instances  to  bring  his  volume  up  to  date.  For  instance, 
much  of  what  is  said  concerning  the  influence  of  alcohol  on  indicators,  on  page 
12,  is  based  on  a  paper  the  conclusions  of  which  have  been  shown  to  be  the 
result  of  working  with  impure  alcohol.  In  other  words,  pure  alcohol  does  not 
appreciably  affect  the  color  reactions  of  most  of  the  important  indicators. 
R.  Schmitt's  process  for  the  manufacture  of  synthetic  salicylic  acid  is  not  re- 
ferred to  in  connection  with  this  article,  yet  this  method  has  probably  super- 
seded all  others  for  manufactuiing  salicylic  acid. 
