Am-/a°nuyi^ari11-}     Chemical  Observations  on  Tartar  Emetic.  33 
ever,  that  several  specimens  have  yielded  more  antimony  than  is  ob- 
tainable from  a  salt  of  the  formula  (SbOKC4HP6,JH20).  We  have 
investigated  the  cause  of  this  anomaly  and  find  it  to  be  due  to  the  ab- 
sence from  the  salt  of  the  proportion  of  water  indicated  by  the  usual 
formula,  loss  having  occurred  from  the  efflorescence  of  the  crystals, 
which  readily  takes  place  when  they  are  kept  in  air.  That  this  is  the 
cause  of  the  discrepancy  was  proved  by  estimating  the  water  in  a 
specimen  which  had  afforded  an  anomalous  result.  The  specimen  se- 
lected for  this  purpose  was  that  numbered  1  in  the  foregoing  table, 
which  contained  an  amount  of  antimony  corresponding  to  102"3  of 
crystallized  tartar  emetic.  This  salt,  on  being  dried  between  100°- 
110°,  lost  only  0'52  per  cent,  of  water,  instead  of  2*72  per  cent.,  and 
by  calculating,  on  this  basis,  the  percentage  of  crystallized  tartar 
emetic,  it  is  found  to  be  102*2  per  cent.,  a  result  which  agrees  with 
that  obtained  by  the  direct  determination  of  the  antimony.  The  oc- 
currence of  efflorescence  to  a  greater  or  less  extent  therefore  explains 
these  higli  results. 
A  few  specimens  afforded  results  rather  below  the  average,  notably 
the  specimen  numbered  12  in  the  table.  Xone  of  these  specimens  dis- 
solved completely  in  the  necessary  quantity  of  cold  water.  Two 
grams  of  the  specimen  numbered  12  in  the  table  were  warmed  to 
about  50°  C.  with  3-1  cc.  of  water.  This  liquid  when  cooled  to  15° 
C.  and  maintained  for  some  hours  at  that  temperature  yielded  crystals 
which  were  recognized  as  acid  tartrate  of  potassium.  The  potassium 
in  the  salt  was  also  estimated  and  found  to  be  higher  than  that  re- 
quired by  the  formula  (SbOKC4H406,JH20).  The  rotatory  power  of 
a  4  per  cent,  solution  was  determined  at  15°  C.  in  a  tube  200  mm. 
long.  The  angle  of  rotation  was  —  10'5°,  whence  [  a]D=131*25°,  a 
result  which  approximately  agrees  with  that  which  had  been  previ- 
ously obtained  with  a  solution  of  tartar  emetic  known  to  contain  5  per 
cent,  of  acid  tartrate  of  potassium.  It  was  thus  proved  that  the  speci- 
men contained  about  five  per  cent,  of  acid  tartrate  of  potassium.  This 
specimen,  which  was  in  fine  powder,  had  also  probably  suffered  ef- 
florescence, but  we  had  not  a  sufficient  quantity  to  determine  whether 
this  was  the  case.  Whether  this  impurity  had  been  fraudulently  added, 
or  had  arisen  from  careless  preparation  of  the  salt  or  from  a  mode  of 
decomposition  of  the  pure  sale  at  present  unknown,  it  is  impossible  to 
say.  Inasmuch  as  other  specimens  which  afforded  low  results  like- 
wise failed  to  completely  dissolve  in  the  requisite  quantity  of  cold 
