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  XLII. 
  — 
  Some 
  Observations 
  on 
  Fish, 
  in 
  relation 
  to 
  Diet. 
  By 
  John 
  Davy, 
  M.D., 
  

   F.R.S. 
  Lond. 
  & 
  Edin., 
  Inspector-General 
  of 
  Army 
  Hospitals, 
  &c. 
  

  

  (Read 
  18th 
  April 
  1853.) 
  

  

  What 
  are 
  the 
  nutritive 
  qualities 
  of 
  fish, 
  compared 
  with 
  other 
  kinds 
  of 
  animal 
  

   food 
  ? 
  Do 
  different 
  species 
  of 
  fish 
  differ 
  materially 
  in 
  degree 
  in 
  nutritive 
  power 
  ? 
  

   Have 
  fish, 
  as 
  food, 
  any 
  peculiar 
  or 
  special 
  properties? 
  These 
  are 
  questions, 
  

   amongst 
  many 
  others, 
  which 
  may 
  be 
  asked, 
  but 
  which, 
  in 
  the 
  present 
  state 
  of 
  

   our 
  knowledge, 
  I 
  apprehend 
  it 
  would 
  be 
  difficult 
  to 
  answer 
  in 
  a 
  manner 
  at 
  all 
  

   satisfactory. 
  

  

  On 
  the 
  present 
  occasion, 
  I 
  shall 
  attempt 
  little 
  more 
  than 
  an 
  opening 
  of 
  the 
  

   inquiry, 
  and 
  that 
  directed 
  to 
  a 
  few 
  points, 
  — 
  chiefly 
  those 
  alluded 
  to 
  in 
  the 
  fore- 
  

   going 
  queries. 
  

  

  1. 
  Of 
  the 
  Nutritive 
  Poiver 
  of 
  Fish. 
  

  

  The 
  proposition 
  probably 
  will 
  be 
  admitted, 
  that 
  the 
  nutritive 
  power 
  of 
  all 
  the 
  

   ordinary 
  articles 
  of 
  animal 
  food, 
  at 
  least 
  of 
  those 
  composed 
  principally 
  of 
  mus- 
  

   cular 
  fibre, 
  or 
  of 
  muscle 
  and 
  fat, 
  to 
  whatever 
  class 
  belonging, 
  is 
  approximately 
  

   denoted 
  by 
  their 
  several 
  specific 
  gravities, 
  and 
  by 
  the 
  amount 
  of 
  solid 
  matter 
  

   which 
  each 
  contains, 
  as 
  determined 
  by 
  thorough 
  drying, 
  or 
  the 
  expulsion 
  of 
  the 
  

   aqueous 
  part, 
  at 
  a 
  temperature 
  such 
  as 
  that 
  of 
  boiling 
  water, 
  not 
  sufficiently 
  high 
  

   to 
  effect 
  any 
  well-marked 
  chemical 
  change. 
  

  

  In 
  the 
  trials 
  I 
  have 
  made, 
  founded 
  on 
  this 
  proposition, 
  the 
  specific 
  gravity 
  has 
  

   been 
  ascertained 
  in 
  the 
  ordinary 
  hydrostatical 
  way; 
  — 
  the 
  portions 
  subjected 
  to 
  

   trial, 
  in 
  the 
  instance 
  of 
  fish, 
  have 
  been 
  taken 
  from 
  the 
  thicker 
  part 
  of 
  the 
  back, 
  

   freed 
  from 
  skin 
  and 
  bone, 
  composed 
  chiefly 
  of 
  muscle. 
  And 
  the 
  same 
  or 
  similar 
  

   portions 
  have 
  been 
  used 
  for 
  the 
  purpose 
  of 
  determining 
  their 
  solid 
  contents, 
  dried 
  

   in 
  platina 
  or 
  glass 
  capsules 
  of 
  known 
  weight, 
  and 
  exposed 
  to 
  the 
  process 
  of 
  drying 
  

   till 
  they 
  ceased 
  to 
  diminish 
  in 
  weight. 
  

  

  The 
  trials 
  on 
  the 
  other 
  articles 
  of 
  diet, 
  made 
  for 
  the 
  sake 
  of 
  comparison, 
  both 
  

   as 
  regards 
  specific 
  gravity 
  (excepting 
  the 
  liquids), 
  and 
  the 
  abstraction 
  of 
  the 
  

   hygroscopic 
  water, 
  or 
  water 
  capable 
  of 
  being 
  dissipated 
  by 
  the 
  degree 
  of 
  tem- 
  

   perature 
  mentioned, 
  have 
  been 
  conducted 
  in 
  a 
  similar 
  manner. 
  

  

  The 
  balance 
  used 
  was 
  one 
  of 
  great 
  delicacy, 
  at 
  home, 
  or 
  a 
  small 
  portable 
  one, 
  

   when 
  from 
  home, 
  of 
  less 
  delicacy, 
  yet 
  turning 
  readily 
  with 
  one-tenth 
  of 
  a 
  grain. 
  

  

  The 
  results 
  obtained 
  are 
  given 
  in 
  the 
  following 
  tables. 
  In 
  the 
  first, 
  on 
  some 
  

   different 
  species 
  offish; 
  in 
  the 
  second, 
  on 
  some 
  other 
  articles 
  of 
  animal 
  food. 
  

  

  I 
  have 
  thought 
  it 
  right, 
  whenever 
  it 
  was 
  in 
  my 
  power, 
  to 
  notice 
  not 
  only 
  the 
  

   time 
  when 
  the 
  fish 
  were 
  taken, 
  but 
  also 
  the 
  place 
  where 
  they 
  were 
  procured, 
  — 
  not 
  

  

  VOL. 
  XX. 
  PART 
  IV. 
  7 
  Z 
  

  

  