﻿X-EAY 
  EXAMINATION" 
  OF 
  PAINTINGS 
  BURROUGHS 
  531 
  

  

  colors, 
  pure 
  and 
  mixed, 
  is 
  X 
  rayed, 
  one 
  notes 
  that 
  only 
  a 
  few 
  are 
  

   undeniably 
  dense 
  and 
  that 
  others, 
  even 
  under 
  the 
  ideal 
  conditions 
  

   of 
  the 
  exj)eriment, 
  are 
  alike 
  in 
  wealoiess 
  or 
  in 
  utter 
  penetrability. 
  

   The 
  whites 
  are 
  generally 
  heavy, 
  since 
  the 
  common 
  forms 
  of 
  white 
  

   pigment 
  are 
  made 
  from 
  zinc 
  or 
  lead. 
  Mercury 
  vermilion 
  has 
  a 
  

   not 
  surprising 
  density. 
  All 
  metal 
  and 
  mineral 
  compounds 
  have 
  an 
  

   effect 
  in 
  the 
  X 
  ray. 
  But 
  vegetable 
  colors 
  or 
  chemical 
  compounds, 
  

   used 
  to-day 
  as 
  substitutes 
  for 
  the 
  old 
  earths 
  and 
  minerals, 
  show 
  

   differences 
  in 
  density 
  only 
  when 
  the 
  X 
  ray 
  is 
  so 
  soft 
  that 
  it 
  will 
  not 
  

   penetrate 
  the 
  coat 
  of 
  plaster 
  or 
  white 
  pigment 
  which 
  was 
  ordinarily 
  

   used 
  as 
  a 
  ground 
  or 
  basis 
  for 
  painting. 
  We 
  are 
  faced, 
  then, 
  with 
  the 
  

   conclusion 
  that 
  our 
  study 
  of 
  pictures 
  with 
  the 
  X 
  ray 
  is 
  based 
  on 
  the 
  

   density 
  of 
  a 
  comparatively 
  few 
  colors. 
  

  

  Fortunately 
  for 
  our 
  study 
  these 
  paints 
  were 
  indispensable 
  to 
  the 
  

   old 
  masters. 
  White 
  lead 
  and 
  dense 
  earth 
  colors 
  are 
  worked 
  gen- 
  

   erally 
  into 
  all 
  parts 
  of 
  old 
  pictures. 
  We 
  see 
  in 
  the 
  X 
  ray 
  the 
  design 
  

   of 
  the 
  picture, 
  the 
  outlines, 
  and 
  the 
  brush 
  marks 
  recorded 
  in 
  the 
  

   underpainting 
  as 
  well 
  as 
  the 
  surface 
  painting. 
  If 
  an 
  artist 
  began 
  

   painting 
  a 
  profile 
  to 
  the 
  left 
  and 
  then 
  painted 
  over 
  it 
  a 
  full 
  view 
  

   of 
  the 
  face, 
  we 
  may 
  trace 
  both 
  efforts 
  in 
  the 
  X 
  ray. 
  If 
  he 
  shifted 
  

   an 
  outline 
  a 
  mere 
  eighth 
  of 
  an 
  inch, 
  we 
  may 
  note 
  the 
  fact 
  in 
  the 
  

   X 
  ray. 
  If 
  the 
  picture 
  had 
  once 
  been 
  pierced 
  with 
  holes 
  and 
  these 
  

   holes 
  painted 
  over, 
  we 
  may 
  see 
  the 
  holes. 
  And 
  if 
  two 
  men 
  have 
  

   worked 
  on 
  the 
  same 
  picture 
  in 
  different 
  styles 
  (like 
  different 
  hand- 
  

   writings) 
  we 
  may 
  be 
  able 
  to 
  distinguish 
  between 
  them 
  more 
  carefully 
  

   in 
  the 
  X 
  ray 
  than 
  on 
  the 
  surface 
  of 
  the 
  work. 
  

  

  In 
  utilizing 
  these 
  facts 
  one 
  moves 
  slowly. 
  The 
  process, 
  as 
  dis- 
  

   tinct 
  from 
  the 
  principles 
  involved, 
  is 
  rather 
  complicated. 
  In 
  the 
  

   first 
  place 
  general 
  conditions 
  may 
  indicate 
  the 
  genuineness 
  of 
  a 
  

   picture, 
  since 
  modern 
  pictures 
  and 
  v/orkmanship 
  differ 
  in 
  the 
  X-ray 
  

   shadowgraph 
  in 
  characteristic 
  fashion. 
  Then 
  comparison 
  between 
  

   the 
  X 
  ray 
  and 
  the 
  painted 
  surface 
  tells 
  us 
  which 
  shapes 
  or 
  brush 
  

   marks 
  recorded 
  on 
  the 
  film, 
  but 
  not 
  visible 
  on 
  the 
  surface 
  of 
  the 
  

   picture, 
  must 
  be 
  inside 
  the 
  painting, 
  atid 
  therefore 
  earlier 
  in 
  date. 
  

   Finally, 
  close 
  observation 
  of 
  style 
  and 
  condition 
  may 
  suggest 
  facts 
  

   which 
  can 
  be 
  compared 
  with 
  the 
  evidence 
  obtained 
  from 
  X 
  rays 
  of 
  

   undoubted, 
  dated, 
  and 
  well-preserved 
  pictures. 
  

  

  It 
  is 
  fairly 
  evident 
  that 
  the 
  larger 
  the 
  collection 
  of 
  X 
  rays 
  the 
  

   greater 
  one's 
  Imowledge 
  and 
  confidence 
  in 
  the 
  value 
  of 
  careful 
  com- 
  

   parison. 
  The 
  Fogg 
  JSIuseum 
  now 
  has 
  a 
  file 
  of 
  about 
  1,000, 
  representing 
  

   the 
  characteristics 
  of 
  many 
  artists 
  and 
  illustrating 
  the 
  j)roblems 
  lying 
  

   in 
  wait 
  for 
  the 
  student. 
  The 
  collection 
  is 
  far 
  from 
  complete. 
  But 
  

   it 
  is 
  already 
  serviceable, 
  suggesting 
  in 
  detail 
  the 
  complications 
  already 
  

   mentioned. 
  "Accepted 
  " 
  pictures 
  by 
  the 
  same 
  artist, 
  for 
  example, 
  

  

  