﻿THE 
  

  

  AMERICAN 
  JOURNAL 
  OF 
  SCIENCE 
  

  

  [FOURTH 
  SERIES.] 
  

  

  Art. 
  XY. 
  — 
  Hot 
  Water 
  and 
  Soft 
  Glass 
  in 
  Their 
  Thermo- 
  

   dynamic 
  Relations 
  / 
  by 
  C. 
  Barus.* 
  

  

  1. 
  It 
  is 
  my 
  purpose 
  in 
  the 
  present 
  address 
  to 
  discuss 
  the 
  

   solvent 
  action 
  of 
  hot 
  water 
  on 
  ordinary 
  glass, 
  or 
  indeed 
  on 
  any 
  

   silicate. 
  That 
  these 
  reactions 
  occur 
  abundantly 
  in 
  nature 
  is 
  

   well 
  known 
  ; 
  in 
  the 
  laboratory, 
  however, 
  they 
  are 
  as 
  a 
  rule, 
  

   difficult 
  to 
  produce 
  in 
  such 
  a 
  way 
  as 
  to 
  give 
  an 
  insight 
  into 
  the 
  

   quantitative 
  relations 
  involved. 
  About 
  ten 
  years 
  ago, 
  I 
  made 
  

   some 
  curious 
  experiments 
  which 
  seemed 
  to 
  give 
  promise 
  in 
  

   this 
  direction. 
  I 
  have 
  recently 
  repeated 
  and 
  extended 
  them, 
  

   carrying 
  out 
  the 
  suggestions 
  indicated 
  on 
  a 
  larger 
  scale 
  and 
  

   with 
  entire 
  success. 
  I, 
  therefore, 
  take 
  pleasure 
  in 
  communi- 
  

   cating 
  the 
  results 
  obtained, 
  interpreted 
  as 
  a 
  whole 
  and 
  from 
  a 
  

   somewhat 
  broader 
  point 
  of 
  view 
  than 
  was 
  originally 
  permitted. 
  

  

  Among 
  natural 
  silicates 
  and 
  in 
  a 
  scale 
  of 
  increasing 
  acidity, 
  

   we 
  are 
  apt 
  to 
  find 
  the 
  acid 
  rocks 
  less 
  fusible 
  than 
  the 
  basic 
  

   rocks, 
  and 
  the 
  aqueous 
  fusion 
  may 
  be 
  presumed 
  to 
  bear 
  a 
  defi- 
  

   nite 
  relation 
  to 
  the 
  igneous 
  fusion. 
  Thus, 
  for 
  instance, 
  an 
  

   obsidian 
  which 
  Prof. 
  Iddings 
  and 
  I 
  examined, 
  fused 
  aqueously 
  

   at 
  about 
  1250°, 
  whereas 
  the 
  pnmice 
  resulting 
  did 
  not 
  fully 
  fuse 
  

   until 
  about 
  1650° 
  was 
  reached. 
  Similarly 
  an 
  aqueous 
  basic 
  

   silicate, 
  fusing 
  at 
  incipient 
  redness, 
  showed 
  complete 
  igneous 
  

   fusion 
  at 
  about 
  1200°. 
  The 
  effect 
  of 
  composition 
  will 
  neces- 
  

   sarily 
  have 
  to 
  be 
  deferred 
  until 
  the 
  scope 
  of 
  experiments 
  like 
  

   the 
  present 
  has 
  been 
  worked 
  out, 
  but 
  in 
  a 
  laboratory 
  attack 
  of 
  

   the 
  subject 
  one 
  is 
  more 
  apt 
  to 
  reach 
  results 
  with 
  the 
  fusible 
  

  

  * 
  A 
  lecture 
  delivered 
  before 
  the 
  Physical 
  Society 
  of 
  the 
  University 
  of 
  Got- 
  

   tingen. 
  

  

  Am. 
  Jour. 
  Sci.— 
  Fourth 
  Series, 
  Vol. 
  IX, 
  Xo. 
  51.— 
  March, 
  1900. 
  

   12 
  

  

  