﻿400 
  SUNDRY 
  IMPROVEMENTS 
  IN 
  

  

  flexible 
  tube 
  extending 
  to 
  an 
  air 
  pump, 
  the 
  flasks 
  may 
  be 
  exhausted, 
  

   and 
  then 
  closed. 
  A 
  small 
  quantity 
  of 
  water 
  having 
  been 
  previously 
  

   introduced 
  into 
  one 
  of 
  them, 
  if, 
  while 
  the 
  exhaustion 
  is 
  sustained, 
  the 
  

   other 
  flask 
  be 
  refrigerated 
  by 
  ice 
  and 
  salt, 
  the 
  water 
  will 
  be 
  frozen.* 
  

  

  The 
  intelligent 
  chemist 
  will 
  perceive 
  that 
  this 
  apparatus 
  may 
  be 
  ap- 
  

   plied 
  to 
  the 
  purpose 
  of 
  desiccation 
  by 
  placing 
  the 
  article 
  to 
  be 
  dried 
  

   in 
  one 
  receptacle, 
  and 
  quick 
  lime, 
  chloride 
  of 
  calcium, 
  or 
  concentrated 
  

   sulphuric 
  acid, 
  in 
  the 
  other. 
  The 
  orifice 
  of 
  the 
  receptacles 
  may 
  be 
  

   made 
  larger 
  without 
  inconvenience. 
  Two 
  large 
  cylinders, 
  for 
  instance, 
  

   may 
  be 
  used. 
  

  

  I 
  propose, 
  as 
  soon 
  as 
  I 
  have 
  leisure, 
  to 
  apply 
  the 
  principle 
  illustrated 
  

   by 
  this 
  apparatus, 
  to 
  the 
  distillation 
  or 
  desiccation 
  of 
  many 
  substances 
  

   which 
  are 
  liable 
  to 
  injury 
  when 
  exposed 
  to 
  heat, 
  or 
  air. 
  I 
  conceive 
  

   that 
  there 
  is, 
  by 
  means 
  of 
  analogous 
  apparatus, 
  a 
  fruitful 
  field 
  for 
  im- 
  

   provement 
  in 
  the 
  arts. 
  I 
  conceive 
  that 
  it 
  may 
  be 
  employed 
  in 
  the 
  

   preservation 
  of 
  meat, 
  milk, 
  fruit, 
  vegetables, 
  and 
  the 
  making 
  of 
  cheese 
  ; 
  

   also 
  in 
  pickling 
  and 
  preserving, 
  f 
  

  

  * 
  For 
  the 
  information 
  of 
  readers 
  who 
  may 
  not 
  be 
  chemists, 
  I 
  subjoin 
  the 
  following 
  explana- 
  

   tion 
  of 
  the 
  cause 
  of 
  the 
  congelation 
  of 
  the 
  water. 
  

  

  So 
  long 
  as 
  no 
  condensation 
  is 
  effected, 
  of 
  the 
  thin 
  aqueous 
  vapour, 
  which, 
  when 
  water 
  is 
  

   present, 
  must 
  occupy 
  the 
  cavity 
  of 
  the 
  instrument, 
  that 
  vapour 
  prevents, 
  by 
  its 
  pressure, 
  or 
  

   tension, 
  the 
  production 
  of 
  more 
  vapour: 
  but 
  when, 
  by 
  means 
  of 
  cold, 
  the 
  vapour 
  is 
  condensed 
  

   in 
  one 
  bulb, 
  its 
  evolution 
  in 
  the 
  other, 
  containing 
  the 
  water, 
  being 
  unimpeded, 
  proceeds 
  rapidly. 
  

   Meanwhile, 
  the 
  water 
  becomes 
  colder, 
  and 
  finally 
  freezes, 
  from 
  losing 
  the 
  caloric 
  which 
  the 
  

   vaporization 
  requires. 
  

  

  According 
  to 
  Wollaston, 
  one 
  grain 
  of 
  water, 
  converted 
  into 
  vapour, 
  holds 
  as 
  much 
  caloric 
  

   as 
  would, 
  by 
  its 
  abstraction, 
  reduce 
  thirty-one 
  grains 
  from 
  60° 
  F. 
  to 
  the 
  freezing 
  point; 
  and 
  

   the 
  caloric 
  requisite 
  to 
  vaporize 
  four 
  grains 
  more, 
  if 
  abstracted 
  from 
  the 
  residual 
  twenty-se- 
  

   ven 
  grains, 
  would 
  convert 
  them 
  into 
  ice. 
  

  

  t 
  This 
  figure 
  repre- 
  

   sents 
  a 
  very 
  large 
  Cryo- 
  

   phorus, 
  the 
  blowing 
  of 
  

   which 
  I 
  superintended; 
  

   and 
  by 
  means 
  of 
  which, 
  about 
  twelve 
  years 
  ago, 
  I 
  successfully 
  repeated 
  Wollaston's 
  experi- 
  

   ment. 
  

  

  This 
  instrument 
  is 
  about 
  four 
  feet 
  long, 
  and 
  its 
  bulbs 
  are 
  about 
  five 
  inches 
  in 
  diameter. 
  

  

  o 
  

  

  