THE  AMERICAN 
JOURNAL  OF  PHARMACY. 
DECEMBER,  1876. 
SPECIFIC  GRAVITY  OF  FLUID  EXTRACTS. 
BY  G.   H.  CHAS.  KLIE. 
The  "  Pharmacopoeia  "  gives  formula  for  quite  a  number  of  fluid 
extracts,  with  mode  of  preparation  circumstantially  described,  and 
apparently  all  proper  precaution  taken  to  insure  efficient  preparations. 
An  experienced  operator,  if  he  uses  good  drugs,  will  no  doubt  gener- 
ally make  good  fluid  extracts.  What  the  "  Pharmacopoeia  "  fails  to 
give  is  a  standard  to  measure  the  strength  of  the  fluid  extracts  by. 
If  such  an  one  had  been  adopted,  very  likely,  more  uniformity  in 
strength  would  result  in  this  class  of  preparations. 
Of  the  different  methods  to  find  the  strength  of  fluid  extracts, 
specific  gravity,  presumably,  is  as  good  as  any.  Its  adoption  as  the 
standard  would  force  the  preparer,  if  he  wanted  to  attain  it,  to  use  the 
prescribed  menstrua.  Another  point  in  its  favor  is  :  it  is  easily  ascer- 
tained and  in  a  comparatively  short  time. 
Precipitation  is  very  accurate  in  estimating  the  strength  of  fluid 
extracts,  but  it  consumes  more  time  and  does  not  indicate  the 
menstrua. 
To  understand  the  specific  gravity  of  the  different  extracts  properly, 
that  of  the  menstrua,  with  which  they  are  severally  prepared,  must  be 
taken  into  consideration,  or  rather,  in  what  approximate  proportion  the 
menstruum  exists  in  the  extracts  when  done.  The  "  Pharmacopoeia" 
directs  the  use  of  six  different  primary  menstrua,  viz.  :  Alcohol  alone, 
and  alcohol,  glycerin  and  water  in  5  proportions,  and  several  secondary 
menstrua  of  alcohol  and  water.  Six  primary  menstrua  are  given  in 
the  list  below,  one  of  them  being  diluted  alcohol,  which  alone  is  not 
directed  in  any  of  the  fluid  extracts.  The  specific  gravity  in  the  list 
of  extracts  marked  "  purchased"  seems  to  indicate  that  one  of  them 
was  made  with  alcohol  and  the  others  with  dilute  alcohol.    One  of 
34 
