AmAp?^r'x?77.rm'}  Use  °f  B°oks  h  Students  and  Assistants.  165 
After  the  above,  the  only  chance  of  success  rested,  perhaps,  in  the 
employment  of  purified  oleic  acid  (for  the  preparation  see  "  A.  J.  Ph.," 
January  number,  1877,  page  4),  although  the  experience  of  high  chem- 
ical authorities  as  to  its  rapid  change  into  crystalline  elaidic  acid  on 
contact  with  nitrous  acid,  seemed  to  speak  much  against  a  favorable 
result.  Actual  experience  seems  in  this  case  to  have  contradicted  all 
theories,  for  not  only  does  it  yield  a  beautiful  pale-yellow  ointment 
(specimen  submitted),  which  undergoes  no  change  in  color  nor  con- 
sistency, but  its  composition,  as  regards  its  mercurial  constituents,  is 
closely  analogous  to  the  preparation  of  the  "  U.  S.  Pharmacopoeia." 
A  solution  thereof  in  petroleum  benzin,  ether  or  alcohol  shows  a 
beautiful  yellow  precipitate  of  equal  amount  of  unchanged  mercuric 
sub-nitrate  and  the  same  quantity  of  the  oleate  as  the  officinal  article, 
while  the  nitrous  acid  of  the  decomposed  mercuric  deutonitrate  seems 
just  to  create  sufficient  elaidic  acid  to  make  its  consistency  that  of 
simple  cerate. 
The  theory  that  elaidic  acid  has  the  power  to  change  admixed  oleic 
acid  indefinitely  into  the  former  seems  also  not  confirmed,  for  although 
we  have  kept  specimens  for  months,  the  consistency  has  not  changed. 
The  odor  of  it  is  not  near  as  objectionable  as  the  product  of  the  "  U. 
S.  P.,"  and  as  they  are  both  mainly  oleates,  there  can  be  no  possible 
objection  to  its  therapeutical  employment. 
In  conclusion,  I  would  state  that  the  proportions  of  mercury  and  nitric 
acid  employed  were  strictly  those  of  the  "  Pharmacopoeia,"  only  the 
equal  quantity  of  purified  oleic  acid  being  substituted  for  the  lard.  No 
particular  precautions  are  necessary  in  regard  to  heat,  no  further  than 
that  the  oleic  acid  should  be  heated  to  the  full  extent  of  a  water-bath 
without  pressure,  before  adding  the  mercurial  solution,  and  should  be 
kept  at  that  point  until  all  reaction  and  effervescence  has  ceased,  where- 
upon it  is  to  be  stirred  until  it  becomes  cold  and  congealed. 
Philadelphia,  Fa  ,  March,  1877. 
HINTS  ON  THE  USE  OF  BOOKS  BY  STUDENTS  AND 
ASSISTANTS  IN  PHARMACY. 
By  J.  B.  Moore. 
It  is  presumed  that  the  library  of  every  intelligent  pharmacist  should 
contain,  at  least,  the  following  books,  viz.:  U.  S.  Pharmacopoeia,  U. 
S.  Dispensatory,  Fowne's  or  Attfield's  Chemistry,  Morfit's  Chemical 
