ON  THE  MYRONATE  OF  POTASH  FROM  BLACK  MUSTARD.  237 
suits  of  M.  Bussy  have  been  confirmed  by  other  authors,  who 
have  added  several  facts  relating  to  the  composition  and  decom- 
position of  the  myronate  of  potash. 
To  prepare  this  salt  in  the  state  of  crystals  we  commence  by 
macerating  the  black  mustard  in  two  successive  portions  of 
rectified  spirit  and  then  in  two  portions  of  cold  water.  The  my- 
ronate is  contained  in  the  aqueous  liquors.  These  are  evaporated 
to  a  syrupy  consistence,  and  the  residue  heated  with  weak  spirit. 
The  liquid  becomes  turbid  on  cooling.  It  is  filtered  and  concen- 
trated, when  a  deposit  of  crystals  of  myronate  of  potash  takes 
place.  These  may  be  purified  by  a  second  crystallization.  Five 
hundred  grammes  of  black  mustard  have  given  by  this  process 
one  gramme  of  colorless  crystallized  myronate  of  potash  ;  1500 
grammes  have  given  7.5  grammes. 
One  hundred  parts  of  myronate  of  potash  contain  ; — 
Carbon  29.98 
Hydrogen 
Nitrogen 
Sulphur 
Oxygen 
Potash 
4.91 
3.97 
14.93 
34.92 
11.29 
100.00 
These  numbers  correspond  to  the  formula — 
K0,C,„H,,NS,0,3{?)  _ 
When  we  treat  the  myronate  of  potash  with  recently-prepared 
myrosine  (aqueous  extract  of  white  mustard),  a  strong  odor  of 
essential  oil  of  mustard  is  manifested.  The  reaction  does  not 
give  rise  to  the  disengagement  of  gas.  When  it  has  terminated, 
if  we  submit  the  aqueous  liquid  to  distillation,  the  essential  oil  of 
mustard  passes  over  with  the  water,  and  a  milky  acid  liquor  re- 
mains in  the  retort.  This  liquid  holds  sulphur  in  suspension. 
It  contains  some  sulphate  of  potash  in  solution  ;  but  the  sulphate 
equals  only  a  fourth  of  the  sulphur  present  in  the  myronate. 
Evaporated,  the  liquid  in  question  leaves  a  residue  from  which 
weak  spirit  extracts  some  fermentable  sugar.  When  this  is  con- 
verted into  alcohol,  if  we  boil  the  fermented  liquid  with  a  few 
drops  of  sulphuric  acid  neutralize  with  chalk,  and  add  yeast,  a 
fresh  fermentation  takes  place  j  proving  that  a  new  portion  of 
