192  Gleanings  from  the  German  Journals.  {AmApHf;i89ialm* 
Lavender  salts. — A  wide-mouth,  ground-stoppered  bottle  is  filled 
with  cubes  of  clear  ammonium  carbonate;  the  interstices  are  rilled 
with  the  following  solution:  100  lavender  oil,  5-0  spirit  of  ammonia 
and  85-0  alcohol. — E.  Dieterich,  Pharm.  Centralhalle,  1891,  134. 
Gentisin. — This  yellow  crystalline  substance  from  gentian  by 
boiling  with  hydriodic  acid  is  demethylated  forming gentisein  C13H805 
which  crystallizes  with  2H20  in  fine  straw-yellow  needles  ;  these 
become  anhydrous  at  1 00°  C.  By  boiling  gentisein  with  acetic 
anhydride  and  anhydrous  sodium  acetate  a  triacetyl  derivative  is 
formed,  crystallizing  in  large,  lustrous,  white  needles  easily  soluble 
in  glacial  acetic  acid,  difficultly  soluble  in  alcohol.  From  these 
results  gentisin  C14H10O5  is  the  methyl  ether  of  gentisein  C13H502 
(0H)3,  and  the  formula  can  be  written  C13H602(OCH8)(OH)2.--Von 
Kostanecki,  Schwz.  Wochensch.  f.  Pharm.,  1 891 ,  59. 
Estimation  of  arsenic  in  acids. — M.  Kretzschmar  recommends,  in 
case  of  hydrochloric  acid,  to  add  sodium  carbonate  to  20  gm.  acid 
largely  diluted  with  water  until  a  faint  acid  reaction  remains.  Then 
render  alkaline  with  ammonia,  add  some  yellow  ammonium  sulphide, 
supersaturate  with  C.  P.  hydrochloric  acid  and  precipitate  As2S3  by 
H.,S,  warming  the  solution ;  this  precipitation,  which  in  other 
methods  requires  15-24  hours,  is  complete  in  2  hours.  The  As2S$ 
is  thoroughly  washed,  dissolved  by  use  of  KOH  and  bromine  water, 
made  slightly  acid  with  HC1  and  then  H3A.s04  precipitated  by 
addition  of  ammonia  and  magnesia  mixture;  weigh  as  Mg2As207. 
In  the  case  of  sulphuric  acid,  S.  Prauss  dilutes  10  cc.  with  water 
and  generates  hydrogen  by  addition  of  pure  zinc.  The  evolved  gases 
are  passed  for  2  hours  through  standardized  nitrate  of  silver  solution  ; 
at  the  end  of  this  time  the  undecomposed  silver  nitrate  is  estimated 
volumetrically  by  sulphocyanate  of  ammonium.  12  molecules 
silver  nitrate  are  decomposed  by  one  molecule  As2Os.  The  results 
agree  closely  with  those  obtained  by  gravimetric  methods. — 
Chemiker  Ztg.}  1891,  299  and  300. 
Depilatory  powder. — A  harmless  remedy  is  made  containing 
strontium  sulphide;  this  has  the  advantages  over  the  sulphides  of 
arsenic,  calcium  and  barium,  in  not  being  poisonous,  in  being  per- 
manent and  that  in  its  application  H2S  is  not  evolved.  It  is  patented 
in  Germany  under  the  name  "Antikrinin." — Chemiker  Ztg.}  1 891 , 
227. 
