AmAP0r"fi9w"m"}  Seed  of  Rhus  Glabra.  157 
many  respects  from  the  oil  which  occurs  in  the  seed.  Its  specific 
gravity  was  taken  at  20°  C.  as  a  semi-solid  and  at  35 0  C.  as  a  liquid. 
The  former  was  09412  and  the  latter  was  0-933.  Like  the  Rhus 
seed-oil,  it  is  non-drying,  but  a  single  test  indicated  that  it  had  more 
of  the  drying  properties  than  the  seed-oil.  This  may  have  been  due 
to  the  fact  that  more  foreign  matter  existed  in  this  than  in  the  seed- 
oil.  This  statement  is  probable,  inasmuch  as  the  iodine  values  in 
the  two  oils  are  about  the  same.  Three  iodine  determinations  gave 
the  following : 
I.  '1816  gramme  of  husk-oil  absorbed     .    "01584  gramme  of  iodine 
II.  '1560       "  "  "        .  .    "01364        "  " 
III.  -1638         "  "  "  .    .  -CI422 
I.  H.  III. 
Per  cent,  of  iodine  87*1  87-4  86*7  ;  average,  87*2 
Two  determinations  of  saponification  value  gave  the  following 
results : 
I.  1*5044  grammes  of  husk-oil  required,  "2699  gramme  of  potassium  hydroxide 
II.  1*6205        "  "  "       '2917        "  "  " 
1.  11. 
Calculated  in  milligrammes  per  gramme  of  KOH,  179*3    i8o"i  ;  average,  179*7 
The  chief  difference  between  these  two  oils  is  due  to  unsaponifiable 
matter,  to  an  easily  oxidizable  substance  and  to  the  fact  that  the 
husk  oil  contains  two  distinct  oils.  It  was  found  that  by  treating 
with  acetone,  about  80  per  cent,  of  the  oil  dissolved,  and  by  evapo- 
rating off  the  acetone  was  obtained  as  a  light-yellow  liquid.  The 
insoluble  substance  appeared  as  a  black  semi-solid.  The  light- 
yellow  oil  was  compared  with  the  seed-oil,  but  was  found  to  differ 
in  various  ways.  The  black  oil  and  the  unsaponifiable  substance  pres- 
ent in  it  are  under  examination  at  the  present  time. 
The  Cholesterols. — The  cholesterols  are  among  the  most  mysteri- 
ous compounds  with  which  the  plant  and  physiological  chemist  has 
to  deal.  Little  more  can  be  said  of  them  than  the  simple  fact  that 
they  are  complex  mon-atomic  alcohols  of  aromatic  nature,  and  that 
they  are  widely  distributed  in  both  the  plant  and  animal  world. 
There  is,  at  the  present  time,  no  good  reason  for  their  existence,  and 
yet  as  plant  and  animal  analyses  progress,  the  more  widely  they 
appear  to  be  distributed.  It  was  formerly  supposed  that  common 
cholesterol  was  almost  or  entirely  of  animal  origin,  and  that  phytos- 
terol,  an  isomeric  form,  was  of  vegetable.    Such  an  idea  is  no  longer 
