﻿Chemistry 
  and 
  Physics. 
  81 
  

  

  believed 
  that 
  a 
  student 
  who 
  is 
  unfamiliar 
  with 
  the 
  calculus 
  should 
  

   have 
  little 
  difficulty 
  in 
  understanding 
  the 
  meaning 
  and 
  use 
  of 
  such 
  

   formulae, 
  provided 
  he 
  is 
  willing 
  to 
  take 
  the 
  author's 
  word 
  for 
  

   the 
  solution 
  of 
  the 
  equations. 
  h. 
  l. 
  w. 
  

  

  5. 
  Organic 
  Chemistry 
  for 
  the 
  Laboratory, 
  by 
  W. 
  A. 
  Noyes. 
  

   8vo, 
  pp. 
  292. 
  Easton, 
  Pa., 
  1916 
  (The 
  Chemical 
  Publishing 
  Co.). 
  

   — 
  This 
  guide 
  for 
  organic 
  preparations 
  now 
  appears 
  in 
  its 
  third 
  

   edition, 
  revised 
  and 
  slightly 
  enlarged. 
  As 
  is 
  well-known, 
  the 
  

   book 
  presents 
  a 
  liberal 
  number 
  of 
  classified 
  and 
  well-selected 
  

   preparations, 
  with 
  full 
  and 
  clear 
  directions 
  and 
  abundant 
  refer- 
  

   ences 
  to 
  the 
  literature. 
  There 
  are 
  132 
  numbered 
  exercises, 
  many 
  

   of 
  which 
  involve 
  several 
  operations, 
  from 
  which 
  more 
  or 
  less 
  

   extensive 
  courses 
  of 
  laboratory 
  work 
  may 
  be 
  selected, 
  h. 
  l. 
  w. 
  

  

  6. 
  Note 
  on 
  the 
  Electrolysis 
  of 
  Gallium 
  • 
  by 
  H. 
  S. 
  Uhlek, 
  

   (communicated). 
  — 
  After 
  the 
  article 
  by 
  Philip 
  E. 
  Browning 
  and 
  

   myself 
  had 
  appeared 
  (vol. 
  xlii, 
  p. 
  389, 
  November, 
  1916), 
  I 
  met 
  

   with 
  a 
  difficulty 
  in 
  the 
  electrolysis 
  of 
  gallium 
  which 
  caused 
  me 
  

   to 
  lose 
  much 
  time, 
  and 
  hence 
  it 
  seems 
  desirable 
  to 
  present 
  this 
  

   brief 
  note 
  of 
  warning 
  for 
  the 
  benefit 
  of 
  other 
  investigators 
  who 
  

   may 
  be 
  working 
  in 
  the 
  same 
  field. 
  In 
  order 
  to 
  increase 
  the 
  purity 
  

   of 
  Some 
  gallium 
  which 
  had 
  been 
  obtained 
  by 
  the 
  electrolytic 
  

   method 
  outlined 
  in 
  the 
  above 
  mentioned 
  paper, 
  the 
  metal 
  was 
  

   dissolved 
  in 
  a 
  hot_ 
  solution 
  made 
  from 
  equal 
  volumes 
  of 
  con- 
  

   centrated 
  nitric 
  acid 
  and 
  water. 
  The 
  resulting 
  solution 
  was 
  

   then 
  made 
  strongly 
  alkaline 
  by 
  the 
  addition 
  of 
  caustic 
  soda 
  so 
  

   that 
  the 
  gallium 
  hydroxide 
  was 
  thoroughly 
  dissolved. 
  An 
  

   attempt 
  to 
  electrolyze 
  this 
  solution 
  was 
  unsuccessful, 
  from 
  the 
  

   practical 
  point 
  of 
  view, 
  for 
  only 
  an 
  insignificant 
  mass 
  of 
  gallium 
  

   deposited 
  on 
  the 
  cathode 
  in 
  the 
  course 
  of 
  several 
  days. 
  The 
  addi- 
  

   tion 
  to 
  the 
  electrolyte 
  of 
  several 
  times 
  its 
  volume 
  of 
  a 
  very 
  con- 
  

   centrated 
  aqueous 
  solution 
  of 
  sodium 
  hydroxide 
  increased 
  the 
  

   rate 
  of 
  deposition. 
  to 
  some 
  extent 
  but 
  not 
  enough 
  to 
  be 
  compara- 
  

   ble 
  with 
  the 
  rate 
  obtained 
  w 
  r 
  ith 
  alkaline 
  solutions 
  containing 
  no 
  

   nitrates. 
  To 
  prove 
  that 
  no 
  blunder 
  had 
  been 
  made, 
  the 
  solution 
  

   was 
  neutralized 
  with 
  hydrochloric 
  acid 
  and 
  the 
  precipitated 
  gal- 
  

   lium 
  hydroxide 
  was 
  thoroughly 
  washed 
  and 
  thus 
  freed 
  from 
  sol- 
  

   uble 
  compounds. 
  The 
  precipitate 
  was 
  then 
  dissolved 
  in 
  an 
  excess 
  

   of 
  caustic 
  soda, 
  after 
  which 
  treatment 
  the 
  solution 
  electrolyzed 
  

   with 
  great 
  facility. 
  The 
  entire 
  experiment 
  was 
  repeated, 
  com- 
  

   mencing 
  with 
  1*05 
  grams 
  of 
  metallic 
  gallium. 
  Only 
  4*5 
  ms 
  ' 
  were 
  

   deposited 
  on 
  the 
  cathode 
  in 
  11 
  2*75 
  hours. 
  After 
  neutralization, 
  

   and 
  so 
  forth, 
  the 
  metal 
  was 
  recovered 
  with 
  promptness. 
  It 
  is 
  

   certain, 
  therefore, 
  that 
  the 
  presence 
  of 
  sodium 
  nitrate 
  greatly 
  

   retards 
  the 
  electrolytic 
  deposition 
  of 
  gallium. 
  Although 
  no 
  

   quantitative 
  comparisons 
  were 
  made, 
  the 
  rates 
  of 
  deposition 
  with 
  

   and 
  without 
  the 
  presence 
  of 
  chlorides 
  seemed 
  to 
  be 
  about 
  the 
  

   same. 
  The 
  warning 
  is, 
  — 
  avoid 
  nitrates. 
  h. 
  s. 
  u. 
  

  

  7. 
  The 
  Condensation 
  of 
  Gas 
  Molecules.— 
  -By 
  using 
  cadmium 
  

   instead 
  of 
  mercury 
  vapor 
  R. 
  W. 
  Wood 
  has 
  performed 
  some 
  very 
  

   interesting 
  and 
  instructive 
  preliminary 
  experiments 
  on 
  the 
  con- 
  

  

  Am. 
  Jour. 
  Sci.— 
  Fourth 
  Series, 
  Vol. 
  XLIII, 
  No. 
  253.— 
  January, 
  1917. 
  

   6 
  

  

  