292  Gleanings  from  the  German  Journals.  {Amxu°^fgoarm' 
silver  chromate  upon  the  fibres  and  a  paper  of  uniform  red  color 
results.  If  such  paper  be  immersed  in  a  solution  containing 
chlorides,  the  red  silver  chromate  is  converted  into  white  silver 
chloride  and  the  paper  becomes  colorless ;  3  parts  of  a  chloride  in 
10,000  parts  solution  can  be  recognized.  The  reagent,  because  of 
its  simplicity,  is  advanced  for  industrial  and  household  purposes. — 
Hoogvliet,  Pharm.  Weekblad;  Apoth.  Ztg.,  1890,  165. 
Pyrrol  is  recommended  by  Prof.  A.  Ihi  as  a  delicace  reagent  for  a 
class  of  essential  oils  which  contain  derivatives  of  allyl-benzol,  as 
cinnamic  aldehyde,  eugenol,  safrol  and  anethol.  The  most  delicate 
reaction  was  obtained  with  oil  of  cinnamon.  A  very  dilute  alcoholic 
solution  of  this  oil,  to  which  a  small  quantity  of  an  alcoholic  pyrrol 
solution  and  then  a  little  concentrated  hydrochloric  acid  is  added,  pro- 
duces first  a  yellowish  red  color,  changing  rapidly  to  dark  red  and 
finally  produces  a  dark  precipitate.  Traces  of  cinnamon  oil  and  of 
pyrrol  can  be  identified  by  this  test.  Oils  of  cloves  and  pimenta  in 
alcoholic  solution,  as  above,  give  rise  to  beautiful  carmine  colora- 
tions. Oil  of  sassafras  forms  a  beautiful  rose-red  coloration.  The 
oils  of  fennel,  anise  and  star-anise  give  only  faint  reactions. — 
Chemiker  Ztg.,  1890,  438. 
tthyl  bromide,  made  by  the  following  directions,  is  obtained  free 
from  ether,  which  is  so  difficult  to  remove.  To  a  cold  mixture  of 
12  parts  sulphuric  acid  and  7  parts  alcohol  of  specific  gravity  0-8 16 
are  added  slowly  12  parts  powdered  potassium  bromide  and  the 
mixture  distilled  from  a  sand-bath.  The  distillate  is  repeatedly 
agitated  with  fresh  portions  of  water,  as  long  as  this  removes  any- 
thing ;  then  the  ethyl  bromide  is  agitated  with  strong  sulphuric 
acid,  allowed  to  stand  for  12  hours,  removed  from  the  acid  and 
shaken  up  with  10  per  cent,  solution  of  potassium  carbonate, 
separated,  dried  by  use  of  fused  calcium  chloride  and  distilled  at  a 
temperature  of  380  C.  from  a  water  bath.  Ninety-nine  parts  of  the 
distillate  are  mixed  with  1  part  absolute  alcohol  for  preservation. 
The  preparation  has  a  sp.  gr.  1-455  to  r'459  an^  boils  at  38  to  400 
C. — Dr.  C.  Brunnengraber,  Apoth.  Ztg.,  1890,  130. 
Cantharidin. — Of  various  solvents,  E.  Dieterich  finds  acetone  to 
be  the  best  for  this  substance,  requiring  only  38  parts  at  150  C. 
to  dissolve  1  part  cantharidin  ;  of  chloroform,  65  parts  are  neces- 
sary ;  of  ether,  550  parts.    To  make 
Oleum  Cantharidini. — One  part  finely  powdered  cantharidin  is 
