﻿certain 
  Alloys 
  of 
  Silver 
  and 
  Copper. 
  

  

  485 
  

  

  of 
  heat 
  sustained 
  by 
  the 
  iron 
  during 
  its 
  transfer 
  from 
  the 
  crucible 
  to 
  the 
  

   calorimeter 
  ; 
  and 
  (4) 
  the 
  radiation 
  from 
  this 
  instrument. 
  

  

  The 
  melting-point 
  of 
  copper 
  has 
  not 
  been 
  exactly 
  ascertained 
  ; 
  and 
  I 
  

   experienced 
  great 
  difficulty 
  in 
  determining 
  it 
  by 
  means 
  of 
  the 
  calorimeter, 
  

   as 
  the 
  molten 
  metal 
  adheres 
  tenaciously 
  to 
  the 
  iron. 
  Accuracy 
  on 
  this 
  

   point 
  is 
  not 
  absolutely 
  essential 
  to 
  this 
  inquiry, 
  and 
  I 
  therefore 
  adopted 
  

   1330° 
  C, 
  as 
  this 
  is 
  considered 
  by 
  Dr. 
  Van 
  Biemsdijk* 
  to 
  be 
  the 
  probable 
  

   melting-point 
  of 
  pure 
  copper. 
  

  

  The 
  several 
  alloys 
  were 
  synthetically 
  prepared 
  by 
  melting 
  together 
  pure 
  

   silver 
  and 
  pure 
  copper 
  ; 
  and 
  as 
  soon 
  as 
  the 
  crucible 
  containing 
  the 
  fused 
  

   metal 
  was 
  withdrawn 
  from 
  the 
  furnace, 
  a 
  small 
  portion 
  of 
  the 
  thoroughly 
  

   stirred 
  alloy 
  was 
  granulated 
  and 
  set 
  aside 
  for 
  analysis. 
  

  

  The 
  requisite 
  data 
  for 
  ascertaining 
  the 
  melting-point 
  of 
  each 
  alloy 
  

   were 
  furnished 
  by 
  an 
  experiment 
  similar 
  to 
  that 
  which 
  was 
  made 
  for 
  

   determining 
  the 
  specific 
  heat 
  of 
  the 
  iron, 
  and 
  in 
  calculating 
  the 
  result 
  

   it 
  was 
  only 
  necessary 
  to 
  transpose 
  the 
  equation 
  already 
  given, 
  T 
  being 
  

   the 
  unknown 
  quantity 
  instead 
  of 
  sc. 
  The 
  formula 
  then 
  becomes 
  

  

  T 
  - 
  (P+^g 
  f 
  +j>„Q(e-o 
  +e 
  

  

  p 
  sc 
  

  

  the 
  value 
  assigned 
  to 
  oc 
  being 
  in 
  all 
  cases 
  0*15693, 
  the 
  mean 
  specific 
  heat 
  

   ft 
  of 
  iron, 
  as 
  given 
  above. 
  

  

  To 
  take 
  an 
  example. 
  In 
  one 
  experiment 
  to 
  determine 
  the 
  melting- 
  

   point 
  of 
  the 
  820*7 
  alloy, 
  the 
  following 
  values 
  were 
  obtained 
  : 
  — 
  

  

  P 
  =247-74 
  grms. 
  t 
  = 
  15° 
  C. 
  

  

  2>,<!,+2>„ 
  c„= 
  15-687 
  „ 
  G= 
  56° 
  G. 
  

  

  p 
  = 
  82-55 
  „ 
  

  

  The 
  weight 
  of 
  alloy 
  carried 
  over 
  was 
  3-608 
  grms., 
  the 
  heating 
  effect 
  of 
  

   which 
  was 
  equivalent 
  to 
  that 
  of 
  1-543 
  grin, 
  of 
  iron. 
  Therefore 
  the 
  

   corrected 
  value 
  of 
  p 
  is 
  

  

  82-55 
  + 
  1-543 
  grm. 
  = 
  84-093 
  grms. 
  

  

  Substituting 
  these 
  values 
  in 
  the 
  above 
  equation, 
  

  

  T 
  _ 
  (247-74 
  + 
  15-687) 
  (56-15) 
  Q 
  

   84-093 
  x 
  -15693 
  

  

  = 
  874°-42C. 
  

  

  The 
  results 
  of 
  the 
  experiments 
  are 
  given 
  in 
  the 
  following 
  Table 
  : 
  — 
  

  

  * 
  Archives 
  Neerlandaises, 
  t. 
  iii. 
  (1868). 
  

  

  