370  Gleanings  in  Materia  Medica.  {^"'jSy^sss*''"'* 
placed  in  a  vacuum  over  sulpluiric  acid,  the  color  changes  to  yellow, 
but  on  admitting  moisture  and  oxygen,  both  are  rapidly  absorbed  and 
the  color  changes  to  blue-black.  —  Compt  Rend.,  xcv.,  925. 
Cannabine  Tannate  is  highly  recommended  by  Fronmiiller  as  a 
mild  and  efficient  hypnotic,  which  leaves  no  symptoms  of  intoxication 
and  does  not  produce  constipation,  but  like  opium  it  must  be  given  in 
increased  doses  when  used  for  some  time.  It  is  described  as  a 
yellowish  brown  powder,  insoluble  in  water  and  ether,  scarcely  soluble 
in  alcohol,  of  a  not  unpleasant  odor  and  of  a  bitterish  astringent  taste ; 
under  the  microscope  it  is  seen  to  form  amorphous  pointed  plates. 
The  process  for  its  preparation  is  not  given,  but  is  said  to  be  tedious 
and  difficult  owing  to  its  ready  decomposition ;  but  it  is  stated  to  be 
permanent  and  not  to  lose  its  activity  after  being  mixed  with  sugar. 
On  distilling  hemp  with  water  a  volatile  oil  is  obtained,  consisting 
of  cannabene  and  cannabene  hydride,  the  latter  being  poisonous  and  of 
an  unpleasant  odor  and  taste ;  it  is  not  a  constituent  of  the  cannabine 
tSimmte.—Archiv  d.  Phar.,  Jan.,  1883,  p.  51,  Memorabilien. 
Mesembrianthemum  crystallinum. — H.  Mangon  found  in  the  dried 
leaves  of  the  ice  plant  43  per  cent,  of  salts  of  potassium  and  sodium, 
and  calculates  that  a  hectare  would  be  capable  of  yielding  863  kilos  of 
potassium  carbonate. — Ibid.,  xcvi,  80. 
Ledum  palustre. — The  crystalline  stearopten  from  the  volatile  oil  of 
this  plant  w^as  obtained  by  Grassmaun  (1831)  and  farther  examined  by 
Trapp  (1869)  and  Ivanov  (1876),  who  obtained  different  results  as  to 
its  composition.  Hjelt  and  Collan  have  recently  prepared  this  ledum- 
camphor  and  obtained  from  plants  grown  in  comparatively  dry  soil 
only  a  minute  quantity  of  it  and  no  volatile  oil,  while  the  fresh  plant 
from  wet  localities  yielded  '7  per  cent,  of  oil,  including  camphor.  The 
latter  recrystallized  from  alcohol  is  nearly  inodorous  and  its  ultimate 
analysis  lead  to  the  formula  C25H44O2,  which  comes  near  that  ascertained 
by  Trapp.  The  camphor  melts  at  101  °C.,  and  crystallizes  well  from 
benzol,  also  by  sublimation,  when  it  is  obtained  in  long  white  needles. 
—BericMe,  1882,  p.  2500. 
Mustard  oil  in  the  seeds  of  Cruciferw. — V.  Dircks  determined  the 
following  percentage  quantities  of  mustard  oil :  black  mustard  seed- 
cake, 1.39;  rape-seed  from  '018  to  "037;  rape-seed  cake,  '020  to 
^109;  yellow  mustard  seed-cake,  "018;  turnip  seed,  '038;  seeds  of 
Sinapis  arvensis  .006.  The  quantity  of  oil  decreases  apparently  with 
the  ao-e  of  the  rape  seed-cake,  but  whether  this  is  due  to  a  decomposi- 
