72 
Percentages  in  Solutions. 
Am.  Jour.  Pharm. 
Feb.,  1892. 
The  practice  is  said  to  be  in  use  to  employ  a  certain  amount  of 
the  vanilla  bean  in  the  preparation  of  an  extract  and  making  a  sub- 
sequent addition  of  vanillin.  This  addition  will  give  the  finished 
preparation  an  agreeable  flavor,  and  it  is  possible  that  the  better 
quality  of  commercial  vanilla  extracts  are  made  in  this  way. 
To  what  extent  this  takes  place  is  not  possible  to  tell.  Inci- 
dentally may  be  mentioned  that  the  sale  of  this  and  most  other  flavor- 
ing extracts  has  passed  beyond  the  limits  of  pharmacy  and  into 
the  hands  of  grocers  and  provision  dealers. 
PERCENTAGES  IN  SOLUTIONS. 
By  Joseph  W.  England,  Ph.G. 
Read  at  the  Pharmaceutical  Meeting  of  the  Philadelphia  College  of  Pharmacy,  Jan.  19. 
Concerning  the  subject  of  percentages  in  solutions,  a  sharp  dis- 
tinction should  always  be  made  between  percentage  by  weight  and 
percentage  by  volume.  They  are  by  no  means  identical.  In  the 
former  the  proportions  are  all  by  weight,  in  the  latter  the  solids  are 
by  weight,  and  the  liquids  by  volume.  Where  the  term  percentage 
alone  is  used,  it  is  always  understood  to  be  percentage  by  weight. 
-  Where  percentage  by  volume  is  meant,  it  is  always  so  expressed. 
Now  concerning  percentage  or  percentage  by  weight.  The  matter 
of  mixing  one  liquid  with  another  is  merely  a  question  of  relative 
proportions.  It  is  in  the  dissolving  of  a  solid  or  solids  in  a  liquid, 
where  difficulties  arise,  especially  where  it  is  desired  to  ascertain  the 
quantity  necessary  for  a  fluidounce,  or  a  pint,  etc.,  of  a  certain  per 
cent,  solution. 
In  the  majority  of  instances  the  solvent  used  is  water,  the  weight 
of  each  fluidounce  being  455-7  grains,  and  of  each  pint  7,291  grains. 
Suppose,  for  example,  that  one  wishes  to  make  a  fluidounce  of  a  10  per 
cent,  cocaine  solution,  then  we  would  make  45  5*7  grains,  the  weight 
of  a  fluidounce  of  water,  90  per  cent.,  and  ascertain  the  10  per  cent, 
of  cocaine  by  simple  proportion,  as  follows  : 
90:  10  ::  4557:  50-6  grains. 
In  other  words,  50-6  grains  of  the  salt  dissolved  in  one  fluidounce 
of  water  would  give  a  10  per  cent,  solution,  slightly  excess  in 
volume,  to  a  fluidounce,  according  to  the  increase  of  volume  resulting 
from  the  dissolved  salt.    Another  method  may  be  followed.  Mul- 
