386      Hypophosphorous  Acid  and  Hypophosphites.  {^iil^um^' 
been  made  to  effect  this  purpose,  but  as  yet  few  have  been  sold  so  far 
as  my  experience  extends.  The  commonest  way  for  dividing  and  the 
least  reliable  is  to  guess  at  it  by  taking  out  on  the  end  of  the  spatula 
about  as  much  as  the  operator  thinks  will  make  the  proper  quantity  for 
one  paper,  and  having  distributed  the  whole  quantity  into  the  number 
of  papers  ordered,  those  which  seem  to  be  either  too  light  or  heavy 
are  corrected;  this  it  need  only  be  said  is  guessing  about  the 
division. 
Another  and  much  better  method  is  to  spread  the  powder  to  be  di- 
vided upon  a  ground-glass  plate,  arrange  it  into  a  parallelogram  of 
even  thickness,  and  mark  off  the  number  of  parts  into  which  it  should 
be  divided  with  a  straight  edge  spatula  across  the  plate.  Those  who 
practice  this  method  succeed  in  making  divisions  that  are  within  a  frac- 
tion of  a  grain.  Greater  accuracy  can  be  attained  by  using  a  glass 
slab  to  the  underside  of  which  has  been  pasted  a  piece  of  letter  paper 
upon  which  have  been  ruled  six  or  eight  parallel  lines;  at  right  ang- 
les to  these  an  equal  number  of  lines  have  also  been  ruled,  all  at 
equal  distances;  at  the  margins  of  the  paper  the  numbers  1,  2,  3,  etc. 
are  made  between  the  lines  so  that  any  given  number  can  be  made  by 
multiplying  one  number  by  any  other  that  will  give  the  desired  num- 
ber of  powders.  When  odd  numbers  such  as  13,  17  or  19  are  or- 
dered the  best  plan  is  to  weigh  off  the  13th,  17th,  or  19th  of  the 
whole  weight  and  then  the  remainder  will  be  very  readily  divided  in 
the  manner  above  described.  For  those  who  prefer  a  more  finished 
affair  than  that  just  described,  the  glass  slab  should  have  the  edges 
bevelled,  and  the  lines  etched  on  it,  the  figures  being  engraved  on  the 
bevelled  edge. 
HYPOPHOSPHOROUS  ACID  AND  THE  OFFICINAL 
HYPOPHOSPHITES. 
By  Frank  X.  Moerk,  Ph.G. 
Contribution  from  the  Chemical  Laboratory  of  the  Philadelphia  College  of 
Pharmacy.— No.  55. 
II.     EXAMINATION  OF  OFFICINAL  HYPOPHOSPHITES. 
Before  taking  up  this  part  of  the  subject  a  correction  must  be 
made  and  some  additional  experiments  recorded  under  the  bromine 
method.  On  page  332  the  value  of  1  cc.  NaOH  is  stated  to  be  0*01685 
gm.  KH2P02  this  should  be  0*01735  ;  the  additional  experiments  have 
reference  to  some  impurity  in  the  bromine  used  which  necessitates  a 
f 
