336      PRODUCTS  OF  THE  FERMENTATION  OF  MUCIC  ACID. 
PRODUCTS  OF  THE  FERMENTATION  OF  MUCIC  ACID. 
M.  Rigault  observes  (Comp.  Rend.  1. 1.  p.  782)  that  between  citric 
and  mucic  acids  there  exist  very  remarkable  relations  :  The  two 
bodies  have  an  almost  identical  composition,  mucic  acid  having 
the  same  elements  as  citric  acid,  crystallised  with  two  equiva- 
lents of  water.  Besides  this,  when  submitted  to  the  action  of 
potash -in  a  state  of  fusion,  both  are  decomposed,  and  form  1 
molecule  of  oxalic  acid  and  2  molecules  of  acetic  acid,  which 
seems  to  indicate  that  not  only  are  their  elements  almost  the 
same,  but  that  they  are  similarly  arranged.  Personne  has  shown 
that  under  the  influence  of  a  ferment,  citrate  of  lime  is  convert- 
ed into  acetate  and  butyrate  of  lime,  which  M.  Rigault  finds  to 
be  the  case  with  mucate  of  lime.  He  fermented  mucate  of  lime 
(using  muscular  flesh  as  the  ferment),  at  a  temperature  varying 
from  25Q  to  35°  C.  The  gases  given  off  were  carbonic  acid  and 
hydrogen,  the  proportion  of  the  latter  constantly  varying. 
After  six  weeks  the  evaporated  liquor,  treated  with  sulphuric 
acid,  yielded  acetic  and  butyric  acids,  and  perhaps  a  very  small 
quantity  of  metacetic  acid.  Supposing  the  products  of  the 
metamorphosis  of  mucic  acid  to  consist  entirely  of  acetic  and 
butyric  acids,  the  reaction  will  be  expressed  by  the  following 
equation  : 
3(C12H10O16)=3(C4H4O4)+C8H8O4+16CO2+10H. 
The  small  proportion  of  butyric  acid,  however,  and  its  late  ap- 
pearance among  the  products,  induces  the  author  to  suppose  that 
this  is  not  an  essential  product,  but  the  result  of  an  accessory 
fermentation  which  goes  on  parallel  with  the  principal  pheno- 
menon, and  is  determined  by  an  altered  portion  of  the  ferment, 
and  then  the  equation  will  be  : 
2(G12HwOM=4(C4H104)+8C02+4H. 
The  identity  of  the  products  of  the  fermentation  of  mucic 
and  citric  acids,  justifies  the  opinion  which  attributes  to  these 
two  bodies  a  simular molecular  constitution,  and  strengthens  the 
hope  that  citric  acid  may  one  day  be  obtained  in  the  laboratory 
by  a  process  analogous  to  that  which  gives  mucic  acid. — Qhem. 
News,  London,  May  12th,  1860. 
