Am.  Jour.  Pharm. ) 
Nov.,  1 880.  i 
Chemical  Notes. 
547 
new  determinations  of  the  density  of  chlorine,  made  with  the  greatest 
care  and  with  the  elimination  of  all  known  sources  of  error.  Instead 
of  the  value  1*63  previously  given  by  him,  he  obtains  now  2'05,  a 
number  still  considerably  lower  than  the  normal  density,  2*45.  This 
shows  that  the  abnormal  change  in  the  density  of  chlorine  only  takes 
place  at  a  much  higher  temperature  than  that  necessary  for  iodine.  It 
may  be,  therefore,  that  the  density  of  free  chlorine  (not  liberated  in 
statu  nascendi  from  platinous  chloride),  when  determined  at  very  high 
temperatures,  may  change  also  to  a  degree.  The  experiments  with  free 
chlorine  have  not  as  yet  been  carried  out  at  the  highest  temperatures. 
This  Meyer  proposes  to  do  shortly. — Ber.der  Chem,  (j^j.,  xiii,  p.  1721. 
Organic  Chemistry. —  On  the  Recognition  and  Determination  of  Traces 
of  Carbon  Disulphide. — Prof.  A.  W.  Hofmann  gives  a  means  of  deter- 
mining with  accuracy  very  small  amounts  of  carbon  disulphide.  The 
firm  of  Schimmel  &  Co.,  in  Leipzig,  had  found  in  a  large  shipment  of 
mustard  oil  received  from  Russia  such  amounts  of  carbon  disulphide 
that  reclamation  was  at  once  mide  on  the  ground  of  adulteration.  The 
Russian  firm  then  stated  that  in  the  preparation  of  mustard  oil  from 
Sinapis  juncea^  the  variety  used  in  Russia,  carbon  disulphide  was  neces- 
sarily formed.  Prof.  Hofmann,  being  called  as  an  expert,  testified  that 
such  large  quantities  could  not  be  produced  in  the  process  of  manufac- 
ture, but  at  the  same  time  gave,  as  the  result  of  experiment,  the  state- 
ment that  small  amounts  were  found  in  all  the  mustard  oils,  both  natu- 
ral and  synthetical.  Thus  in  oil  from  Sinapis  juncea  he  found  in  two 
determinations  0*41  and  0*37  per  cent.  ;  in  oil  from  Sinapis  nigra^  0*51 
and  0*56  per  cent.,  and  in  artificial  mustard  oil,,  made  from  allyl  iodide 
and  ammonium  sulphocyanate,  0*32  per  cent,  of  carbon  disulphide. 
These  small  amounts  could  be  shown  qualitatively  by  the  aid  of  the 
xanthogenate  of  copper  reaction,  but  not  determined  quantitatively.  A 
means  of  determining  even  the  slightest  trace,  with  accuracy,  was 
found  in  the  use  of  triethylphosphin,  which  with  carbon  disulphide 
yields  rosy  red  prisms  of  the  compound  (C2H5)3PCS2.  100  parts,  by 
weight,  of  this  precipitate  correspond  to  39*1  parts  of  CS2.  The 
occurrence  of  carbon  disulphide  in  all  the  preparations  of  mustard  oil, 
including  that  prepared  synthetically,  Hofmann  ascribes  to  a  secondary 
reaction,  whereby  aqueous  vapor  first  liberates  hydrogen  sulphide  from 
the  oil,  and  this,  acting  upon  the  allyl  sulphocyanate,  liberates  carbon 
disulphide. — Ibid.^  xiii,  p.  1732. 
On  the  Preparation  of  Tannic  Acid, — The   pulverulent  tannin,  as 
