'""Ni^ifso""  • }  Chemistry  of  Bast  Fibres.  5  5  7 
of  the  solution  with  10  cc.  of  alcohol.  Ten  drops  of  mustard  oil^ 
adulterated  with  bisulphide  of  carbon,  shaken  with  the  above  pocassa 
solution  for  one  minute^  then  supersaturated  with  acetic  acid,  furnishes  a 
liquid,  which  with  a  solution  of  sulphate  of  copper  produces  a  reddish- 
yellow  precipitate.  Pure  mustard  oil,  treated  in  the  same  manner, 
shows  always  an  undesirable  turbidity,  and  after  some  time  also  a 
whitish  deposit,  which,  however,  cannot  be  confused  with  that  pro- 
duced by  bisulphide  of  carbon,  but  which  does  not  exclude  with  cer- 
tainty all  doubts. 
It  is  consequently  the  most  desirable,  under  all  circumstances,  to 
distill  ofF  the  bisulphide  of  carbon,  when  the  quantity  present  will 
admit,  and  particularly  to  determine  its  specific  gravity  and  boiling 
point.  In  the  case  now  before  us,  the  adulterated  oil  had  the  sp. 
gr.  I  073  at  20°,  while  the  same,  after  the  above  described  process  of 
distillation,  approached  the  correct  number,  1021,  and  the  specific 
gravity  of  the  distillate  was  increased  to  over  i*20. 
By  the  long  preservation  of  the  questionable  adulterated  oil  by  the 
side  of  a  specimen  of  the  pure  oil,  the  remarkable  fact  was  shown, 
that  the  former  in  the  course  of  a  few  months,  even  in  dispersed  light, 
became  colored  very  dark  brown,  and  the  bottom  and  sides  of  the 
flask  become  covered  with  a  dirty,  brown  red  deposit,  while  the  pure 
oil  under  the  same  circumstances  underwent  no  change.  In  exposed 
sunlight,  however,  such  a  remarkable  distinction  is  not  manifest,  as  in 
this  case  the  pure  oil  becomes  also  dark  colored  very  quickly. — Pharm. 
Post,  No.  17,  1880.  'f.  B.  p. 
CHEMISTRY  OF  BAST  FIBRES. 
By  E.  J.  Bevan  and  C.  F.  Cross. 
A  Paper  read  before  the  Owens  College  Chemical  Society,  i6th  April.  Published 
by  Plamer  &  Howe,  Manchester.    See  also  Chem.  Ne^s,  p.  42,  '77. 
The  authors'  investigations  have  been  confined  to  jute  and  esparto, 
the  former  as  a  peculiarly  typical  bast  fibre,  the  latter  as  representing 
monocotyledonous  growth. 
The  inorganic  constituents  of  the  normal  jute  fibre  are — 
(^7.)  W  ater  of  hydration^  varying  from  10  to  12  per  cent,  of  its  weight, 
with  the  temperature  and  hygrometric  state  of  the  air.  It  is  to  be 
regarded  as  dependent  both  on  the  chemical  nature  and  structure  of  the 
fibre  (chemical  adhesion),  although  scarcely  upon  its  external  structure, 
(capillarity),  as  conjectured  by  Sir  W.  Thompson. 
