332  Microscopical  Examination  of  Powders.  {Am  jS^'i89o*rm' 
the  piperaceous  taste  is  considered,  and  the  fact  that  the  fruit  con- 
tains enough  sugar  to  warrant  its  employment  for  the  preparation 
of  an  alcoholic  beverage  and  of  vinegar,  it  is  surprising  that  the 
different  parts  of  the  plant  have  not  been  subjected  to  analysis. 
The  bark  contains  tannin ;  the  gum  resin  contains  about  60  per 
cent,  of  resin  and  a  little  volatile  oil,  and  the  fruit  was  supposed  by 
Landerer  (1862)  to  contain  piperine,  which  supposition,  however, 
does  not  appear  to  have  been  verified  or  disproved  by  later  investi- 
gations. 
MICROSCOPICAL  EXAMINATION  OF  POWDERS. 
By  Hans  M.  Wilder. 
II. 
Reflected  Light. — Although  the  examination  of  a  powder  is  chiefly 
conducted  by  transmitted  light,  many  valuable  hints  may  be  obtained 
by  first  examining  the  powder  by  reflected  light;  of  course,  with  the 
dry  powder  against  a  dark  background,  and  then  when  mixed  with 
water  (or  other  fluid)  under  a  cover  glass,  similarly. 
Specific  Gravity. — It  will  in  many  cases  (especially  with  com- 
pound powders)  be  of  great  help  to  be  able  to  examine  the  several 
constituents  of  a  powder  separately,  at  any  rate  some  of  them. 
This  can  be  attained  by  an  elutriation  process  ("  water  sifting'  "  as 
Remington  happily  calls  it).  Fill  a  conical  glass  (graduate)  three- 
fourths  full  of  water,  sprinkle  on  top  of  the  water  some  of  the 
powder  to  be  examined,  and  allow  the  particles  to  settle  undisturbed  ; 
the  heaviest  sink,  of  course,  first.  After  a  short  time  examine  the 
particles  floating  on  top,  and  those  on  the  bottom  separately. 
Several  powders  are  a  good  deal  heavier  than  water,  when  a  strong 
solution  of  salt,  or  a  heavier  liquid  should  be  used. 
Sections. — A  preliminary  study  of  sections  of  the  drug  in  question 
is  of  great  assistance  in  recognizing  the  powder.  Transverse  sec- 
tions are  not  of  so  much  use  as  longitudinal  ones  (both  radial  and 
tangential)  because  the  elements  of  the  powder  seldom  will  be  seen 
"  standing  on  end,"  as  it  were ;  they  are  chiefly  seen  from  the  flat 
side  (surface  view). 
Heating. — A  great  help  in  clearing  a  mount,  is  to  heat  the  slide 
until  numerous  small  air-bubbles  appear — until  the  medium  just 
begins  to  boil,  but  not  longer. 
Mounting. — A  mistake,  beginners  are  very  apt  to  make,  is  to  put 
