﻿52 
  W. 
  P. 
  White 
  — 
  Specific 
  Heat 
  Determination. 
  

  

  be 
  the 
  same 
  for 
  different 
  loads 
  in 
  the 
  container. 
  An 
  

   inverted 
  cone 
  on 
  top 
  of 
  the 
  container 
  made 
  that 
  slide 
  

   into 
  the 
  water 
  with 
  less 
  disturbance 
  and 
  chance 
  of 
  spat- 
  

   tering. 
  

  

  III. 
  The 
  Calorimetric 
  Measurement. 
  

  

  The 
  calorimeters 
  had 
  been 
  carefully 
  tested, 
  in 
  connec- 
  

   tion 
  with 
  an 
  electric 
  calibration, 
  and 
  proved 
  very 
  accu- 
  

   rate 
  under 
  the 
  conditions 
  then 
  prevailing. 
  In 
  the 
  

   specific 
  heat 
  work 
  the 
  problem 
  was 
  complicated 
  by 
  the 
  

   necessity 
  of 
  exposing 
  the 
  calorimeter 
  to 
  the 
  air 
  of 
  the 
  

   room 
  for 
  from 
  7 
  to 
  10 
  seconds 
  at 
  the 
  time 
  of 
  the 
  drop. 
  

   This 
  was 
  the 
  time 
  required 
  to 
  remove 
  the 
  splash 
  guard 
  

   (a 
  wide 
  tube 
  which 
  prevented 
  the 
  water 
  thrown 
  up 
  by 
  the 
  

   drop 
  from 
  getting 
  on 
  the 
  outside 
  of 
  the 
  calorimeter) 
  and 
  

   then 
  to 
  cover 
  calorimeter 
  and 
  jacket. 
  The 
  error 
  in 
  

   this 
  operation 
  was 
  diminished 
  by 
  two 
  modifications 
  of 
  

   the 
  apparatus 
  as 
  described 
  in 
  1910. 
  (1) 
  In 
  the 
  central 
  

   part 
  of 
  the 
  splash 
  guard 
  tube 
  pasteboard 
  replaced 
  the 
  

   brass 
  ; 
  the 
  flow 
  of 
  heat 
  between 
  the 
  room 
  and 
  the 
  cal- 
  

   orimeter 
  rim 
  was 
  then 
  much 
  less 
  rapid, 
  and 
  the 
  cal- 
  

   orimeter 
  at 
  a 
  more 
  uniform 
  temperature 
  at 
  the 
  instant 
  of 
  

   the 
  drop. 
  (2) 
  The 
  calorimeter 
  cover 
  rested 
  in 
  a 
  hori- 
  

   zontal 
  pocket 
  in 
  the 
  jacket 
  cover, 
  from 
  which 
  it 
  was 
  

   pushed 
  by 
  one 
  hand 
  (by 
  means 
  of 
  a 
  rod 
  running 
  through 
  

   the 
  far 
  side 
  of 
  the 
  pocket) 
  ready 
  to 
  be 
  seized 
  by 
  the 
  

   other 
  hand 
  and 
  put 
  in 
  place 
  on 
  the 
  calorimeter. 
  This 
  

   arrangement 
  saved 
  time, 
  and 
  gave 
  a 
  definite 
  known 
  tem- 
  

   perature 
  of 
  the 
  cover. 
  The 
  hand 
  did 
  not 
  touch 
  the 
  cover 
  

   itself, 
  but 
  only 
  a 
  stem 
  of 
  negligible 
  heat 
  capacity 
  and 
  low 
  

   conducting 
  power. 
  

  

  The 
  effect 
  of 
  the 
  exposure 
  to 
  the 
  air 
  was 
  studied 
  by 
  

   special 
  experiments, 
  with 
  the 
  smaller 
  calorimeter, 
  holding 
  

   about 
  1500cc. 
  With 
  the 
  air 
  4° 
  colder, 
  opening 
  the 
  jacket 
  

   with 
  the 
  regular 
  cover 
  still 
  on 
  the 
  calorimeter 
  caused 
  a 
  

   temperature 
  fall 
  of 
  0-0003° 
  per 
  minute, 
  or 
  about 
  one- 
  

   fourth 
  what 
  would 
  have 
  occurred 
  with 
  the 
  whole 
  (closed) 
  

   jacket 
  4° 
  colder. 
  This 
  result 
  is 
  about 
  what 
  would 
  be 
  

   expected 
  in 
  view 
  of 
  the 
  fact 
  that 
  the 
  jacket, 
  made 
  to 
  hold 
  

   the 
  larger 
  calorimeter 
  also, 
  gave 
  an 
  unusually 
  full 
  expo- 
  

   sure 
  when 
  open. 
  It 
  is 
  also 
  easy 
  to 
  see 
  why 
  the 
  effect 
  

   with 
  the 
  room 
  warmer 
  was 
  very 
  much 
  less, 
  and 
  for 
  a 
  

   short 
  opening, 
  as 
  4 
  seconds, 
  was 
  about 
  twice 
  as 
  great 
  in 
  

   proportion. 
  With 
  the 
  calorimeter 
  open 
  the 
  effect 
  of 
  

  

  