NOTES  ON  LEMON-JUICE  AND  ITS  DECOMPOSITION.  79 
from  Glasgow,  from  these  •!  obtained  5 J  ounces  of  juice.  This 
was  very  much  more  aromatic  and  more  delicate  in  its  flavor 
than  lemon-juice.  Its  sp.  g.  was  1'037,  and  contained  32-22 
grains  per  ounce.  It  was,  therefore,  not  so  strong  as  lemon- 
juice. 
Messrs.  Southall,  of  Birmingham,  furnished  a  sample  as  com- 
ing from  the  Olveston  Plantation,  in  Montserrat,  which  had  a 
deep  yellowish-brown  color  ;  this,  I  presume,  was  given  arti- 
ficially, as  that  pressed  by  myself  from  the  fruit  was  nearly 
colorless. 
This  coloration  has  since,  however,  been  shown  to  have  been 
accidental  from  the  containing  vessel. 
A  singular  fact  was  communicated  to  me  by  D.  Davis,  Esq., 
Medical  Inspector  for  Bristol,  which  was  (at  any  rate,  to  me) 
quite  new.  Of  course,  all  chemists  are  aware  that  when  citric 
acid  is  fused  with  potassa  it  is  decomposed  into  oxalic  and  acetic 
acids,  thus  : — 
CeH.O,  +  H,0  =  0,H,0,  +  C,H,0,. 
Citric  Acid.  Oxalic  Acid.    Acetic  Acid. 
But  when  liquor  potassse  is  mixed  with  common  lemon-juice  in 
the  cold,  oxalic  acid  may  be  detected  in  a  few  days. 
When  lemon-juice  is  carefully  evaporated  it  yields  a  rich 
brown  extract,  which  is  very  peculiar  both  in  smell,  taste,  and 
appearance,  so  much  so  that  any  one  accustomed  to  make  these 
experiments  can  in  one  moment  tell  whether  or  not  it  is  a  genu- 
ine juice. 
An  ounce  of  lemon-juice  will  average  27  grains  of  dry  extract 
per  ounce.  After  a  certain  point  the  extract  becomes  carbon- 
ized, having  a  rich  brown  color  and  pleasant  smell.  This  is 
owing  to  its  partial  decomposition  into  acetone,  carbon,  carbonic 
acid,  carbonic  oxide,  and  aconitic  or  pyrocitric  acid. 
2(CeHA)  =  C3H,0  +  SCO,  +  CO  +  C,H,0,  +  211,0. 
Citric  Acid.       Acetoue.  Aconitic  Acid. 
It  seems  quite  impossible  to  evaporate  the  juice  to  dryness 
without  decomposition. 
During  the  first  six  months  of  the  present  year  a  great  num- 
ber of  samples  of  commercial  juice  were  examined;  the  following 
are  a  few  of  them  procured  from  London,  Bristol,  Liverpool, 
