﻿558 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  and 
  4 
  are 
  put 
  in, 
  2 
  and 
  3 
  may 
  be 
  fused 
  but 
  4 
  remains 
  unaffected, 
  

   indicating 
  that 
  the 
  temperature 
  reached 
  the 
  fusing 
  point 
  of 
  3. 
  

  

  These 
  pyramids 
  have 
  been 
  much 
  used 
  by 
  foreign 
  manufacturers 
  

   of 
  clay 
  products 
  and 
  are 
  coming 
  intO' 
  use 
  in 
  the 
  United 
  States. 
  

  

  There 
  are 
  several 
  indirect 
  methods 
  of 
  determining 
  temperatures, 
  

   but 
  that 
  of 
  Bischof 
  (Dingier's 
  Polyt. 
  jour. 
  196: 
  438, 
  525; 
  198: 
  

   396) 
  is 
  perhaps 
  the 
  best 
  known. 
  This 
  consists 
  in 
  increasing 
  the 
  

   refractoriness 
  of 
  weighed 
  samples 
  by 
  adding 
  tc 
  them 
  increasing 
  

   quantities 
  of 
  an 
  intimate 
  mixture 
  of 
  equal 
  parts 
  of 
  chemically 
  pure 
  

   silica 
  and 
  alumina, 
  and 
  heating 
  them 
  with 
  a 
  prism 
  of 
  Saarau 
  fire 
  

   clay 
  (whose 
  fusing 
  point 
  is 
  Soger 
  cone 
  36) 
  to 
  above 
  the 
  melting 
  

   point 
  of 
  wrought 
  iron. 
  While 
  involving 
  more 
  labor 
  than 
  the 
  direct 
  

   method, 
  it 
  has 
  the 
  advantage 
  of 
  requiring 
  only 
  on© 
  standard. 
  

  

  This 
  method 
  was 
  tried 
  by 
  Hofman 
  and 
  Demond 
  (" 
  Further 
  ex- 
  

   periments 
  for 
  determining 
  the 
  fusibility 
  of 
  fire 
  clays 
  ", 
  Trans. 
  

   Amer. 
  inst. 
  min. 
  eng. 
  Mar. 
  1895) 
  who' 
  mixed 
  various 
  samples 
  of 
  

   fire 
  clays 
  with 
  varying 
  proportions 
  of 
  calcium 
  carbonate, 
  and 
  

   calcium 
  carbonate 
  and 
  silica, 
  to 
  render 
  them 
  fusible 
  at 
  temperatures 
  

   below 
  the 
  melting 
  point 
  of 
  platinum, 
  while 
  common 
  brick 
  clays 
  

   were 
  mixed 
  with 
  alumina 
  and 
  silica 
  tO' 
  decrease 
  their 
  fusibility, 
  the 
  

   object 
  of 
  this 
  being 
  to 
  arrive 
  at 
  a 
  standard 
  temperature 
  at 
  which 
  

   both 
  refractory 
  and 
  fusible 
  clays 
  could 
  be 
  tested. 
  The 
  results 
  ob- 
  

   tained 
  at 
  first 
  were 
  very 
  satisfactory, 
  but 
  subsequent 
  ones 
  did 
  not 
  

   result 
  as 
  was 
  desired 
  and 
  the 
  method 
  had 
  to 
  be 
  abandoned. 
  More 
  

   recently 
  however 
  this 
  method 
  has 
  been 
  tried 
  by 
  J. 
  L. 
  ISTewell 
  and 
  

   G. 
  A. 
  Rockwell 
  with 
  much 
  better 
  results 
  {Trans. 
  Amer. 
  inst. 
  min. 
  

   eng. 
  Oct. 
  1898, 
  "A 
  modification 
  of 
  Bischof 
  's 
  method 
  for 
  determin- 
  

   ing 
  the 
  fusibility 
  of 
  clays, 
  as 
  applied 
  to 
  nonrefractory 
  ones, 
  and 
  

   the 
  resistance 
  of 
  fire 
  clays 
  to 
  fluxes 
  ", 
  H. 
  0. 
  Hofman) 
  

  

  In 
  the 
  last 
  experiments 
  the 
  Seger 
  cone 
  26 
  was 
  used 
  as 
  a 
  standard^ 
  

   as 
  it 
  forms 
  the 
  line 
  between 
  refractory 
  and 
  nonrefractory 
  clays, 
  

   the 
  nonrefractory 
  ones 
  being 
  toned 
  up 
  till 
  they 
  show 
  the 
  same 
  

   behavior 
  in 
  the 
  fire 
  as 
  cone 
  26. 
  The 
  amount 
  of 
  toner 
  added 
  then 
  

   gave 
  an 
  idea 
  how 
  far 
  the 
  clay 
  stood 
  below 
  the 
  lower 
  limit 
  of 
  

   refractoriness. 
  

  

  