^"^iZ'iSjt"'"'  \       Sulphovinic  Acid  and  its  Salts.  27 
kept  for  some  hours  in  a  water-bath,  and  at  a  higher  temperature 
decomposition  at  once  ensues.  It  may,  nevertheless,  be  quite  possible 
to  obtain  a  sulphovinic  acid  tolerably  pure  with  alcohol  and  sulphuric 
acid  alone  (instead  of  the  present  tedious  method  based  on  the  decom- 
position of  the  baryta  salt),  by  keeping  the  mixture  at  100°  for  two  or 
three  days,  and  not  acting  upon  too  large  a  quantity.  I  intend  to  try 
this  experiment  shortly. 
To  obtain  sulphovinate  (ethyl-sulphate)  of  Hme,  it  is  best  to  mix 
equal  volumes  of  concentrated  sulphuric  acid  and  alcohol  they  may 
be  mixed  without  any  special  precautions  when  small  quantities  only 
are  used,  and  the  uncovered  vessel  containing  the  mixture  must  be 
transferred  to  a  water-bath  and  kept  there  eight  or  ten  hours  at  least, 
during  the  whole  of  which  time  the  temperature  should  be  100°,  or 
nearly.  The  liquid  will  then  have  acquired  a  slight  degree  of  fluores- 
cence and  a  decided  odor  of  ether  (not  an  odor  of  sweet  oil  of  wine), 
and  should  be  only  very  slightly  colored.  When  cool,  it  is  added  drop 
by  drop,  to  about  twenty  times  its  volume  of  cold,  distilled  water,  care- 
fully avoiding  any  rise  of  temperature,  and  keeping  the  liquid  well  stirred. 
This  solution  is  saturated  with  pulverized  chalk,.added  in  small  quan- 
tities at  a  time,  until  effervescence  ceases.  When  a  slight  excess  of 
chalk  has  been  added^  filter  off  the  sulphate  of  lime,  heat  the  filtrate  in 
the  water-bath  with  a  little  carbonate  of  lime  for  about  a  half  an  hour, 
filter  while  warm,  and  evaporate  at  a  heat  not  exceeding  100°  till  a 
permanent  saline  layer  forms  at  the  surface  then  place  the  capsule 
in  a  dry  or  moderately  dry  place.  In  about  twenty-four  hours  the 
crystals  are  formed  ;  the  mother-water  will  give  another  crop  when 
allowed  to  evaporate  over  sulphuric  acid  or  chloride  of  calcium.  If 
the  chalk  contains  iron  or  manganese,  their  sulphovinates  remain  in  the 
mother-water,  and  are  perfectly  separated  by  pressing  the  crystals. 
Sulphovinate  of  lime  crystallizes  rather  slowly,  even  in  very  concen- 
trated solutions  ;  it  forms  large,  brilliant  plates,  something  like  chlorate 
of  potash  ;  its  composition  is  represented  by  C^HgOjSOg+CaOSOg-j- 
2HO  ;  it  is  very  soluble  in  water  and  in  alcohol.  The  impure  salt  can 
easily  be  purified  by  recrystallization  from  alcohol. 
Sulphovinate  of  baryta  has  a  similar  composition  and  similar  proper 
ties  ;  it  can  be  obtained  in  the  same  manner.  When  the  crystals  are 
pure,  they  form  very  large,  brilliant  plates,  oblique  rectangular  prisms, 
modified  in  certain  angles.     Both  this  salt  and  the  lime-salt  often  per- 
^  During  the  evaporation,  a  slight,  but  distinct,  odor  of  butyric  acid  is  perceptible. 
