154  Seed  of  Rhus  Glabra.  {AmAP°rUii;F904arin" 
This  oil  was  obtained  in  considerable  quantities  by  extracting  the 
ground  seed  with  ether.  Five  exact  determinations  were  made 
giving  an  average  of  9-1  per  cent,  of  oil. 
The  oil  obtained  is  a  light  yellow  mobile  liquid  with  a  peculiar 
odor  and  a  pleasant  taste.  At  —  180  C.  it  becomes  viscous  and  at 
—  240  C.  it  is  a  solid.  The  specific  gravity  at  200  C.  is  0-9203  and 
at  o°,  o  9312.  The  oil  is  soluble  in  nearly  all  of  the  organic  solvents, 
including  ether,  chloroform,  benzene,  carbon  disulphide  and  acetone. 
The  index  of  refraction  at  o°  is  1-48821  and  at  150,  1-48228.  It  is 
optically  inactive. 
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(1)  Rhus  oil ;  (2)  Wheat  oil  ;  (3)  Corn  oil ;  (4)  Linseed  oil. 
The  absorption  spectrum  is  peculiar.  Even  with  comparatively 
thin  layers,  4  to  6  m.m.,  the  violet  rays  of  the  continuous  spectrum 
are  entirely  cut  off  and  in  the  red  portion  about  the  position  of  the 
lithium  band  there  appears  a  perfectly  black  band.  The  above 
is  a  simple  diagram  as  compared  with  linseed,  corn  and  wheat  oils. 
Drying  Properties  of  Rhus  Oil. — Rhus  oil  is  essentially  a  non-dry- 
ing oil.  In  quantities,  the  loss  on  exposure  to  the  air  is  very  small, 
but  when  a  thin  film  of  oil  is  exposed  the  increase  in  weight  is  such 
