﻿Chemistry 
  and 
  Physics. 
  341 
  

  

  in 
  this 
  solution 
  and 
  also 
  decreased 
  the 
  quantity 
  of 
  the 
  active 
  

   oxygen 
  as 
  determined 
  by 
  the 
  iodine 
  method. 
  The 
  author 
  regards 
  

   this 
  compound 
  either 
  as 
  sulphuric 
  oxide 
  in 
  which 
  a 
  single 
  atom 
  

   of 
  oxygen 
  is 
  replaced 
  by 
  a 
  double 
  one, 
  S0 
  2 
  (0 
  2 
  ) 
  or 
  as 
  hydrogen 
  

   peroxide 
  in 
  which 
  the 
  hydrogen 
  is 
  replaced 
  by 
  S0 
  2 
  , 
  corresponding 
  

   to 
  Brodie's 
  class 
  of 
  neutral 
  peroxides. 
  Berthelot's 
  S 
  2 
  0, 
  he 
  regards 
  

   as 
  S0 
  4 
  + 
  S0 
  3 
  . 
  Since 
  in 
  not 
  too 
  dilute 
  sulphuric 
  acid, 
  it 
  dissolves 
  

   without 
  evolution 
  of 
  oxygen, 
  the 
  equation 
  S 
  2 
  7 
  + 
  H 
  2 
  == 
  H 
  2 
  S0 
  4 
  + 
  

   S0 
  4 
  shows 
  the 
  identity 
  of 
  the 
  product 
  thus 
  obtained 
  with 
  that 
  

   produced 
  by 
  electrolysis. 
  — 
  Ber. 
  JBerl. 
  Cherti. 
  Ges., 
  xxiv, 
  1764, 
  

   June, 
  1891. 
  g. 
  f. 
  b. 
  

  

  4. 
  A 
  Dictionary 
  of 
  Applied 
  Chemistry; 
  by 
  T. 
  E. 
  Thorpe 
  

   assisted 
  by 
  eminent 
  contributors. 
  Vol. 
  II, 
  VI 
  4 
  pp., 
  8vo. 
  Lon- 
  

   don, 
  1891, 
  (Longmans, 
  Green 
  & 
  Co.) 
  — 
  The 
  first 
  volume 
  of 
  the 
  

   Dictionary 
  of 
  Applied 
  Chemistry 
  — 
  the 
  successor, 
  on 
  the 
  techni- 
  

   cal 
  side, 
  to 
  Watts's 
  Dictionary 
  of 
  Chemistry 
  — 
  was 
  noticed 
  in 
  

   volume 
  xxxix 
  of 
  this 
  Journal, 
  (p. 
  519). 
  The 
  second 
  volume 
  has 
  

   now 
  appeared 
  and 
  carries 
  the 
  work 
  on 
  from 
  Eau 
  to 
  Nux, 
  and 
  

   hence 
  the 
  completion 
  of 
  the 
  whole 
  may 
  be 
  looked 
  for 
  at 
  an 
  early 
  

   date. 
  Some 
  of 
  the 
  more 
  important 
  subjects 
  discussed 
  at 
  length, 
  

   and 
  in 
  many 
  cases 
  with 
  liberal 
  illustrations, 
  are 
  the 
  following 
  : 
  

   Explosives, 
  by 
  W. 
  H. 
  Deering 
  ; 
  fermentation, 
  by 
  P. 
  F. 
  Frank- 
  

   land 
  ; 
  fuel, 
  by 
  B. 
  H. 
  Brough 
  ; 
  coal 
  gas, 
  by 
  Lewis 
  Wright 
  ; 
  gold, 
  

   by 
  E. 
  J. 
  Ball 
  ; 
  india 
  rubber, 
  by 
  C. 
  A. 
  Burghardt 
  ;■ 
  iron 
  by 
  Thomas 
  

   Turner 
  ; 
  lead 
  by 
  P. 
  P. 
  Bedson 
  ; 
  matches, 
  by 
  E. 
  G. 
  Clayton 
  ; 
  

   napthalene, 
  by 
  W. 
  P. 
  Wynne. 
  The 
  same 
  thorough 
  but 
  concise 
  

   treatment 
  before 
  noted 
  characterizes 
  this 
  volume 
  and 
  makes 
  the 
  

   work 
  as 
  a 
  whole 
  indispensable 
  to 
  all 
  interested 
  in 
  any 
  of 
  the 
  

   many 
  departments 
  of 
  technical 
  chemistry. 
  

  

  5. 
  Measurement 
  of 
  time 
  of 
  Rotation. 
  — 
  The 
  ordinary 
  methods 
  

   of 
  determining 
  the 
  time 
  of 
  very 
  rapid 
  rotation 
  depend 
  in 
  general 
  

   upon 
  the 
  contact 
  of 
  a 
  stylus 
  on 
  the 
  prong 
  of 
  a 
  tuning 
  fork 
  with 
  

   a 
  rotating 
  wheel 
  or 
  cylinder, 
  or 
  on 
  the 
  use 
  of 
  the 
  electric 
  spark 
  

   with 
  a 
  pendulum 
  to 
  indicate 
  the 
  time 
  of 
  rotation. 
  K. 
  Prytz 
  

   departs 
  from 
  both 
  of 
  these 
  methods 
  and 
  employs 
  a 
  falling 
  body 
  

   upon 
  or 
  against 
  which 
  the 
  rapidly 
  rotating 
  body 
  spirts 
  a 
  line 
  jet 
  

   of 
  coloring 
  matter. 
  In 
  this 
  way 
  retardation 
  of 
  contacts 
  is 
  pre- 
  

   vented, 
  and 
  the 
  time 
  is 
  referred 
  directly 
  to 
  the 
  time 
  of 
  a 
  falling 
  

   body. 
  The 
  author 
  gives 
  in 
  detail 
  the 
  method 
  of 
  holding 
  the 
  

   small 
  glass 
  tube 
  containing 
  the 
  coloring 
  matter, 
  and 
  the 
  method 
  

   of 
  obtaining 
  the 
  records. 
  Examples 
  of 
  determination 
  of 
  time 
  

   by 
  this 
  method 
  are 
  given 
  and 
  the 
  author 
  claims 
  that 
  the 
  time 
  of 
  

   a 
  complete 
  revolution 
  of 
  his 
  apparatus 
  could 
  be 
  determined 
  to 
  

   0*00002 
  of 
  a 
  second. 
  — 
  Ann. 
  der 
  Physik 
  und 
  Chonie, 
  No. 
  vii, 
  1891, 
  

   pp. 
  638-651. 
  j. 
  t. 
  

  

  6. 
  Method 
  of 
  determining 
  Specific 
  Heat 
  by 
  means 
  of 
  the 
  

   Electrical 
  Current. 
  — 
  The 
  method 
  ot 
  determining 
  specific 
  heats 
  

   by 
  the 
  use 
  of 
  Joule's 
  law 
  has 
  not 
  proved 
  useful, 
  except 
  in 
  non- 
  

   conducting 
  liquids. 
  Professor 
  Pfaundler 
  has 
  obviated 
  the 
  

   difficulty 
  of 
  conduction 
  through 
  the 
  liquid 
  by 
  employing 
  glass 
  

  

  