Sarco-lactic  (or  Para-lactic)  acid  is  found  in  the  muscles  (hence  also  in
extract  of  beef),  in  the  blood,  and  in  the  urine  after  strong  muscular
exertion.  It  is  the  dextro-rotatory  modification,  and  can  be  produced
together  with  the  laevo-rotatory  modification  by  splitting  up  the  inactive
or  ordinary  lactic  acid.  This  is  accomplished  by  the  fractional  crystal-
lization of  the  strychnine  salt.
Ethylene-lactic  (or  Hydracrylic)  acid  forms  a  syrupy  mass.  It  differs
from  ordinary  lactic  acid  in  yielding  carbonic  and  oxalic  acids  on  oxida-
tion instead  of  acetic  acid,  and  in  not  yielding  an  anhydride  on  heating,
but  breaking  up  into  water  and  acrylic  acid,  whence  the  name  hydra-
crylic.
Oxybutyric  Acid,  CgHgOH.COOH. — An  optically  active  (laevo-rota-
tory) modification  of  this  acid  is  found  in  the  urine  and  the  blood  of
diabetic  patients.
The  dibasic  acids  result  when  the  diatomic  alcohols  are  oxidized  with
nitric  acid  or  by  the  saponification  of  the  cyanogen  derivative  of  the
fatty  acids.
Oxalic  Acid,  COOH.COOH,  occurs  in  many  plants,  as  in  wood-sorrel
(Oxalis  acetosella),  in  the  form  of  KHCgO^,  in  the  vanet\'€S^oi  Kumex,
as  Na2C204  in  varieties  of  Salicornia,  and  as  CaC204  in  rhubarb,  beets,
etc.  It  may  be  formed  by  the  oxidation  of  sugar,  starch,  etc.,  with
nitric  acid,  or  by  fusing", i^elTuIose  with  potassium  and  sodium  hydroxides
the  latter  method  being  employed  on  a  large  scale.  ~  It  crystallizes  with


DERIVATIVES  OF  OPEN-CHAIN  HYDROCARBONS.      539

2HjO,  is  soluble  in  water,  more  difficultly  soluble  in  alcohol,  almost
itl§5Ig^le  in^ther.  Decomposes  olTgtrong  heating,  or  in  the  presence  of
dehydrating  agents  like  sulphuric  acid,  according  to  the  reaction:

COOH— COOH     =     CO2     4-     CO     H-     HaO.
When  heated  with  glycerol,  formic  acid  is  produced.
