226        Pharmaceutical  Notes  from  Purdue  University.  \AmS;^vm' 
the  sodium  salt  with  lead  acetate,  washing  the  precipitate,  dissolving 
in  benzine,  decomposing  with  hydrochloric  acid,  washing  to  remove 
lead,  etc.,  and  warming  in  water-bath  to  remove  benzine. 
Ten  gm.  of  each  sample  were  dissolved  in  twice  the  volume  of 
alcohol,  and  titrated  with  normal  solution  of  caustic  soda,  using 
phenol-phthalein  as  indicator.  Theory  requires  35*4  c.c.  Solution 
in  alcohol  gave  no  indication  of  fixed  oils,  but  the  samples  were  not 
free  from  palmitic  acid,  especially  No.  3,  which  still  had  the  odor  of 
lard  oil.    Numerical  results  are  given  below. 
Specific  Vol.  of  normal  NaOH  Percentage 
gravity.  required.  of  oleic  acid. 
No.  1   -91  31-8  c.c.  87 
No.  2     -89  28  6  "  81 
No.  3   '88  22-4  "  63 
No.  4   -90  351   "  99 
II.     ACIDUM  SULPHUEOSUM. — BY  JOHX  KEXXEDY. 
Preparation. — The  method  of  the  Pharmacopoeia  gave  unsatis- 
factory results,  as  sulphuric  acid  was  found  in  excess  in  the  product, 
while  the  sulphurous  acid  was  deficient.  Much  better  results  were 
obtained  by  reducing  with  copper.  When  the  gas  was  passed  up- 
wards through  a  cylinder  filled  with  lumps  of  moist  charcoal,  and 
then  through  a  wash  bottle,  the  solution  obtained  was  free  from 
sulphuric  acid ;  and  by  surrounding  the  receiver  with  snow,  the 
strength  was  easily  brought  to  12  per  cent.  The  cost  of  the  copper 
cannot  be  considered  an  objection,  for  one  pound  of  the  metal  (costing 
30  cents)  will  theoretically  yield  nearly  four  pounds  of  blue  vitriol, 
worth  ten  to  twelve  cents  per  pound. 
Examination  of  Commercial  Samples. — Specimens  procured  from 
druggists  gave  the  following  results  : — 
Specific  Gravity.    Per  cent,  of  S02 .   Per  cent,  of  H2 SO 4. 
No.  1   1-008  T68"] 
No.  2   1'028  3-28  >  Varying  amounts. 
No.  3   1-036  3*25  J 
No.  4   1-003  None.  0*54 
No.  5   1-006  None.  0"91 
No.  6   1-023  None.  2"67 
Even  if  accurate  tests  cannot  be  made,  a  pharmacist  should  always 
note  whether  his  preparation  has  a  strong  odor  of  S02  before  dis- 
pensing it. 
