454 
V arieties. 
{Am. Jour.  Pharm. 
Sept.,  1878. 
Cantharidin  and  an  Acid  Derivative  thereof.  By  J.  Piccard. — Three  determi- 
nations of  the  vapor-density  of  cantharidin  gave  the  numbers  6-36,  6'6o  and  6'4i  ; 
the  empirical  formula  of  this  body  is  therefore  C10H12O4.  It  enters  into  complete 
fusion  at  2i8°C,  and  not  at  2500,  as  usually  stated. 
By  the  action  of  hydriodic  acid  at  a  temperature  of  ioo°  in  sealed  tubes  it  is 
converted  into  a  body,  which,  although  possessing  the  same  ultimate  composition, 
differs  essentially  from  catharidin.  It  crystallizes  in  needles,  which  melt  at  2780, 
and  are  soluble  in  12  parts  boiling  water;  they  are  freely  soluble  in  alcohol,  slightly 
in  ether,  and  insoluble  in  benzene.  The  solution  ef  this  body  in  glycerin  does  not 
blister  the  skin. 
In  its  chemical  properties  it  differs  from  cantharidin  in  being  a  strong  acid,  dis- 
solving in  and  completely  neutralizing  alkaline  solutions,  decomposing  carbonates 
with  effervescence,  and  being  but  partially  expelled  from  its  salts  by  acetic  acid. 
The  salts  of  cantbaric  acidy  as  this  body  is  termed  by  the  author,  contain  1  atom  of 
metal  to  10  atoms  of  carbon  ;  the  union  of  the  acid  with  bases  is  attended  with  the 
elimination  of  H20  ;  it  is  therefore  a  monobasic  hydrate  ;  its  equivalent,  as  deter- 
mined by  titration  (cryst.  oxalic  acid  =  63)  is  196. 
The  general  formula  of  its  alkaline  salts  is  C10H11O3.OR/.  The  lead  salt  crystal- 
lizes in  long  needles.  Its  formula  is  (C10HnO4)2Pb. — Jour.  Chem.  Soc.  [Lond.], 
March,  1878,  from  Deut.  Chem.  Ges.  Ber.,  x,  1504 — 1506. 
Certain  Reactions  of  Chloral.  By  O.  Wallach. — In  extension  of  his  investiga- 
tion of  the  decomposition  of  chloral  by  potassium  cyanide,  the  author  finds  that  by 
the  action  of  the  more  complicated  cyanides  upon  this  body,  dichloracetic  acid  is 
likewise  formed.  In  the  case  of  potassium  ferrocyanide,  the  formation  of  this  acid 
is  explained  by  the  equation  2FeCy6K4-f  3[C2Cl3OH+H20]=3CCl2HC02K-f 
3KCl+2FeCy3K4-6CNH.  The  resolution  of  chloralcyanhydrate  into  chloral  and 
an  alkaline  cyanide,  by  the  alkalis,  results  in  the  formation  of  dichloracetic  acid,  as 
a  consequence  of  the  mutual  reaction  of  the  immediate  products  of  decomposition, 
thus : 
CCl3CH^+KOH=CCl2HC02H-f  KCl-f  CNH. 
The  above  reactions  are  applied  by  the  author  to  the  production  of  dichloracetic 
ether,  for  which  the  necessary  details  are  given.  By  heating  chloralcyanhydrate 
with  alcohol  for  some  hours  at  i8o°C,  dichloracetic  ether  is  formed ;  the  decompo- 
sition of  chloralcyanhydrate  into  dichloracetic  acid  takes  place,  therefore,  indepen- 
dently of  the  alkalis. 
The  action  of  the  cyanides  upon  butyl-chloral  the  author  finds  to  be  entirely 
analogous  to  that  already  described.  Dichlorobutyric  acid  appears  to  be  formed 
according  to  the  equation  C4Cl3H504-CNK+H20=C4Cl2H602-f-KCl+CNH,  but 
owing  to  its  instability  passes  at  once  into  monochlorocrotonic  acid.  This  reaction 
may  be  advantageously  applied  to  the  production  of  the  latter  acid. 
That  water  plays  a  double  part  in  decompositions  of  this  nature,  viz ,  of  simul- 
taneous oxidation  and  reduction  by  means  of  its  elements,  appears  to  be  the  only 
possible  explanation  of  its  action.    The  author  is  of  opinion  that  the  formation  of 
