240 
GLEANINGS  FEOM  GERMAN  JOURNALS. 
objection  to  the  process  lies  mainly  in  the  difficulty  of  washing 
out  completely  the  bitartrate  of  soda  from  the  precipitate. — Ihid, 
S19,fro7n  Ibid.,  ciii,  495. 
Preparation  of  hydriodio  acid. — Dr.  CI.  Winkler  uses  a  mod- 
erately concentrated  solution  of  iodine  in  sulphide  of  carbon 
contained  in  a  cylinder  kept  cool ;  a  quantity  of  water  is  poured 
upon  the  solution,  varying  in  proportion  to  the  strength  of  the 
acid  desired,  and  sulphide  of  hydrogen  is  then  passed  into  the 
iodine  solution.  The  hydriodic  acid  generated  is  absorbed  by 
the  stratum  of  water,  while  the  sulphur  is  dissolved  by  the 
sulphide  of  carbon ;  the  reaction  is  complete  when  the  violet 
color  of  the  solution  has  passed  into  a  pure  yellow.  The  aqueous 
solution  is  then  heated  to  expel  the  dissolved  sulphide  of  carbon. 
Ibid.  81i),from  Ibid,  cii,  33. 
Preparation  of  cylinders  for  use  with  Brummond'' s  light. — Dr.. 
Jos.  Philipps,  of  Cologne,  gives  the  following  directions: 
Lime  cylinders  are  obtained  by  burning  pieces  of  white  Car- 
rarian  marble,  free  from  iron,  between  coke  for  an  hour  to  an 
hour  and  a  half.  After  the  carbonic  acid  has  been  completely 
expelled,  the  cold  lime  is  sawed  into  pieces  of  about  7  centi- 
metres in  length  and  15  m.  m.  in  thickness,  which  are  preserved 
between  powdered  ]irae.  The  cylinders  are  strong  and  give  a 
bright  light. 
For  magnesia  cylinders  freshly  burned  magnesia  is  mixed  with 
water  to  a  stilf  paste,  which  is  rapidly  put  into  suitable  unsoldered 
moulds  of  sheet  iron  of  the  thickness  of  a  thumb ;  by  striking  «. 
the  moulds  perpendicularly  upon  a  hard  surface,  the  air  is  ex- 
pelled from  the  mass,  which  in  a  few  minutes  becomes  warm, 
when  it  is  put  into  a  warm  oven,  where  it  soon  becomes  very  hot. 
After  about  an  hour  the  cylinders  may  be  removed  from  the 
moulds  ;  they  give  a  brilliant  light,  but  possess  less  strength  than 
the  former. 
Chloride  of  magnesium  cylinders  are  made  in  a  similar'  way  ; 
the  magnesia  is  first  mixed  with  muriatic  acid  to  form  a  thick 
liquid,  when  enough  magnesia  is  rapidly  added  to  form  a  stiff 
mass.  When  finished  these  cyclinders  resemble  porcelain  and 
yieli  a  bright  light,  but  give  off  disagreeable  fumes  when  used. 
Archiv  der  Pharm.,  1869,  Jan»  7,  8. 
