THE 
AMERICAN  JOURNAL  OF  PHARMACY. 
MAY,  1859. 
OBSERVATIONS  ON  THE  ACIDS  EXISTING  IN  THE  JUICES  OP 
RHUBARB  STALKS,  TOMATOES  AND  QUINCES. 
By  Thomas  A.  Lancaster. 
(An  Inaugural  Essay  presented  to  the  Philadelphia  College  of  Pharmacy.) 
My  attention  was  attracted  to  the  subject  of  certain  acid 
vegetable  juices,  by  a  suggestion  of  my  preceptor,  William  Hodg- 
son, Jr.,  as  a  matter  of  importance  to  those  interested  in 
organic  chemistry,  as  the  history  of  the  chemical  constituents 
of  those  juices  is  but  imperfectly  known.  Considering  it  there- 
fore well  worthy  of  further  chemical  investigation,  I  have  at- 
tempted the  examination  of  the  acid  constituents  of  Rhubarb 
Stalks,  and  the  fruits  of  the  Tomato  and  Quince. 
I  have  no  doubt  that  in  a  general  way  the  properties  of  the 
juices  of  rhubarb,  tomatoes  and  quinces,  are  pretty  well 
known  to  the  past  and  present  students  of  chemistry ;  but  as 
regards  the  true  nature  of  their  respective  acidulous  constituents, 
no  thorough  and  reliable  explanation  has  yet  been  given,  so  far 
as  I  can  discover  after  much  research  through  some  of  our  best 
chemical  authorities. 
In  investigating  this  subject  the  labor  was  greatly  increased 
by  the  want  of  some  work  sufficiently  detailing  the  mode  of 
proceeding,  in  order  to  certainly  and  readily  distinguish  between 
citric,  tartaric  and  malic  acids. 
Experiment  1. 
Rhubarb — One  pound  of  the  freshly  cut  stalks  of  the  Rheum 
Rhaponticum,  or  culinary  rhubarb,  was  grated  and  subjected  to 
strong  expression  through  muslin,  which  yielded  thirteen  fluid 
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