﻿of 
  various 
  Substances 
  on 
  Solidification. 
  

  

  215 
  

  

  taken 
  by 
  the 
  usual 
  methods, 
  proved 
  to 
  be 
  7*170, 
  which 
  may 
  be 
  taken 
  as 
  

   the 
  mean 
  specific 
  gravity 
  at 
  57° 
  Fahr. 
  of 
  the 
  whole 
  of 
  the 
  cast 
  iron 
  that 
  

   filled 
  the 
  cone. 
  Eeverting 
  now 
  to 
  the 
  conical 
  vessel 
  which 
  contained 
  at 
  

   60° 
  Fahr. 
  94*112 
  lbs. 
  of 
  distilled 
  water, 
  its 
  capacity 
  being 
  2605*5 
  cubic 
  

   inches 
  : 
  this 
  capacity 
  was 
  enlarged 
  by 
  expansion 
  when 
  filled 
  with 
  molten 
  

   iron 
  to 
  2691*777 
  cubic 
  inches, 
  so 
  that 
  the 
  conical 
  vessel 
  when 
  cold, 
  if 
  it 
  

   had 
  had 
  the 
  same 
  capacity 
  as 
  when 
  filled 
  with 
  liquid 
  iron, 
  would 
  have 
  

   contained 
  97*224 
  lbs. 
  of 
  distilled 
  water. 
  We 
  have 
  now 
  all 
  the 
  elements 
  

   necessary 
  for 
  calculating 
  the 
  specific 
  gravity 
  of 
  the 
  cast 
  iron 
  which 
  filled 
  

   the 
  cone 
  in 
  its 
  molten 
  state, 
  because 
  we 
  have 
  the 
  actual 
  weights 
  of 
  equal 
  

   volumes 
  of 
  distilled 
  water 
  and 
  of 
  molten 
  iron. 
  The 
  final 
  results, 
  then, 
  

   are, 
  that 
  whereas 
  the 
  cast 
  iron 
  which 
  filled 
  the 
  cone 
  had 
  when 
  cold 
  (57° 
  

   Fahr.) 
  a 
  specific 
  gravity, 
  as 
  above 
  given, 
  =7*170, 
  the 
  same 
  cast 
  iron 
  in 
  

   its 
  molten 
  state, 
  as 
  poured 
  into 
  the 
  cone, 
  had 
  a 
  specific 
  gravity 
  of 
  only 
  

   6*650 
  — 
  in 
  this 
  case 
  thus 
  proving 
  that 
  the 
  density 
  of 
  cast 
  iron 
  in 
  its 
  liquid 
  

   state 
  is 
  not 
  greater 
  but, 
  on 
  the 
  contrary, 
  very 
  much 
  less 
  than 
  that 
  of 
  the 
  

   same 
  cast 
  iron 
  at 
  the 
  temperature 
  of 
  the 
  atmosphere. 
  The 
  quality 
  of 
  

   cast 
  iron 
  employed 
  in 
  this 
  experiment 
  was 
  the 
  fine, 
  bright, 
  close-grained 
  

   metal 
  usually 
  employed 
  by 
  Messrs. 
  Maudslay, 
  Sons, 
  and 
  Field 
  for 
  their 
  

   engine-castings, 
  and 
  consisted 
  of 
  

  

  5 
  G-artsherrie, 
  "I 
  

   5 
  Coltness, 
  J 
  

   \ 
  Best 
  scrap* 
  — 
  all 
  by 
  weight. 
  

  

  It 
  may 
  be 
  taken 
  as 
  a 
  typical 
  or 
  medium 
  example 
  of 
  all 
  good 
  grey 
  cast 
  irons. 
  

   I 
  have 
  not 
  been 
  enabled 
  to 
  repeat 
  this 
  experiment 
  with 
  the 
  white, 
  rigid, 
  

   and 
  crystalline 
  cast 
  irons, 
  such 
  as 
  are 
  employed 
  for 
  projectiles 
  and 
  other 
  

   purposes 
  ; 
  but 
  as 
  it 
  is 
  a 
  recognized 
  fact 
  amongst 
  iron-founders 
  that 
  these 
  

   irons 
  expand 
  in 
  the 
  range 
  of 
  temperature 
  between 
  solidity 
  and 
  liquidity 
  

   much 
  more 
  than 
  do 
  grey 
  irons, 
  so 
  we 
  may 
  justifiably 
  conclude 
  that 
  the 
  de- 
  

   crease 
  of 
  specific 
  gravity 
  by 
  fusion 
  of 
  these 
  hard 
  cast 
  irons 
  would 
  be 
  in 
  even 
  

   a 
  greater 
  ratio 
  than 
  that 
  shown 
  by 
  the 
  above 
  experiment 
  on 
  grey 
  iron 
  ; 
  and 
  

   generally 
  the 
  author 
  feels 
  himself 
  justified 
  in 
  concluding 
  that 
  it 
  is 
  not 
  

   true 
  that 
  any 
  cast 
  iron 
  is 
  denser 
  in 
  the 
  fused 
  than 
  in 
  the 
  solid 
  state. 
  Cold 
  

   cast 
  iron, 
  therefore, 
  does 
  not 
  float 
  upon 
  liquid 
  cast 
  iron 
  of 
  the 
  same 
  

   quality 
  by 
  reason 
  of 
  its 
  buoyancy, 
  but 
  in 
  virtue 
  of 
  some 
  force 
  which 
  tends 
  

   to 
  keep 
  it 
  upon 
  the 
  surface 
  of 
  the 
  molten 
  metal 
  in 
  opposition 
  to 
  a 
  very 
  

   considerable 
  want 
  of 
  buoyancy 
  or 
  tendency 
  to 
  sink 
  by 
  greater 
  density 
  on 
  

   the 
  part 
  of 
  the 
  solid 
  iron, 
  which 
  is, 
  by 
  the 
  preceding 
  results, 
  of 
  its 
  

   weight, 
  whatever 
  that 
  may 
  be, 
  and 
  is 
  probably 
  even 
  greater 
  than 
  this 
  in 
  

   the 
  case 
  of 
  hard 
  white 
  cast 
  irons. 
  The 
  author's 
  chief 
  object 
  has 
  been 
  

   thus 
  far 
  rather 
  to 
  prove 
  that 
  the 
  cause 
  assigned 
  by 
  the 
  writers 
  already 
  

   mentioned 
  is 
  not 
  the 
  true 
  cause 
  of 
  the 
  floating 
  of 
  solid 
  upon 
  liquid 
  cast 
  

   iron 
  of 
  the 
  same 
  quality. 
  What 
  is 
  the 
  nature 
  of 
  the 
  force 
  which 
  pro- 
  

  

  * 
  Disused 
  and 
  broken-up 
  castings. 
  

   tol. 
  lira, 
  § 
  

  

  