41 6  ^  Conjiitution  of  Bleaching  Powder.  {"^""siprxs^s^'™" 
Pour  the  thirty  grams  of  syrup  of  gum  into  a  bottle  of  60  grams 
capacity,  and  by  slightly  shaking  cause  it  to  moisten  the  entire  interior 
of  the  bottle.  Introduce  the  phosphorated  oil  (as  many  decigrams  as 
the  emulsion  should  contain  milligrams  of  phosphorus),  shake  well  and 
pour  in  the  peppermint  water.  The  bottle  should  be  shaken,  before 
administering  a  dose,  to  render  the  emulsion  perfectly  homogeneous. — 
Pharm.  fourn.  and  Trans.  [Lond.],  July  3,  1875. 
NOTES  ON  THE  THEORETICAL  VIEWS  OF  THE  CONSTITUTION 
OF  BLEACHING  POWDER. 
BY  DR.  LUNGE. 
The  oldest  formula  proposed  for  bleaching  powder  seems  to  have 
been  CaOCl  (according  to  the  old  notation),  but  in  1835  Balard 
("Annales  de  Chimie  et  de  Physique  "  (2)  Ivii,  p.  225)  after  having  studied 
the  properties  of  sodium  hypochlorite,  came  to  the  conclusion  that  the 
constitution  of  "  chloride  of  lime  "  was  a  similar  one,  and,  doubting 
the  above  formula,  distributed  it  as  an  equivalent  of  calcium  hypochlo- 
rite, and  an  equivalent  of  calcium  chloride  :  CaOClO+CaCl  (or 
CaClgOg+CaClg,  new  notation),  mixed  with  an  excess  of  CaOHO. 
The  celebrated  Gay  Lussac,  in  1842,  gave  further  reasons  for  this 
theory  ("  Annales  de  Chemie  et  de  Physique  "  (3)  v,  p.  273),  and  it 
has  remained  the  dominant  one  up  to  this  day,  and  is  generally  to  be 
found  in  the  ordinary  chemical  text-books.  In  1861,  Fresenius  pub- 
lished ("•  Liebig's  Annalen,"  vol.  cxviii,  p.  217)  researches  upon  this 
subject,  the  result  of  which  led  him  to  the  formula  CaOClO+CaCl, 
2CaOH-4Aq.  But  this  formula  seems  quite  untenable,  despite  the 
high  authority  of  its  proposer  and  the  minuteness  of  his  researches, 
inasmuch  as  it  only  allows  of  a  strength  of  32  per  cent,  available  chlo- 
rine, whilst  it  is  well  known  that  39  per  cent,  can  be  easily  obtained. 
Besides,  BoUey  has  shown  that  the  compound  CaCl,2CaO  is  itself  de- 
composable by  chlorine  into  CaOCl,  and  there  seems  to  be  no  reason 
why  the  action  of  chlorine  should  stop  short  of  this  in  the  ordinary 
manufacture  of  bleaching  powder.  Less  material  is  the  objection 
raised  by  Odling  (in  his  "  Manual  of  Chemistry  ")  that  the  above 
formula  cannot  be  correct,  because  alcohol  does  not  dissolve  calcium 
chloride  from  bleaching  powder,  and  because  the  latter  does  not  de- 
liquesce, for  both  the  one  and  the  other  fact  are  disputed  by  most  other 
observers.    Odling's  own  formula  is  :    Cajci^+HgO.    During  the 
