Here  gold  is  not  of  the  substance,  but  the  place  of  origin  is.  See
Giorgi  (op.  cit)  iv.  50,  et  seq.  Hue  says  (Com.  vii,  p.  38),  that  the
fact  that  the  parties  have  used  a  special  description  such  as  silver
or  golden  candlestick,  shows  that  they  have  agreed  that  such  quality
shall  be  a  condition  of  the  validity  of  the  contract.  Therefore,  if
there  be  a  mistake  as  to  this  quality  the  contract  is  voidable,  not  for


MISTAKE  AS  TO  QUANTITY  IQQ

§  72.      Mistake  as  to  the  Quantity  of  the  Subject-Matter.      If

one  party  intends  to  sell  a  certain  quantity  of  an  article,  and
the  other  party  intends  to  buy  a  different  quantity,  the  con-
tract is  void,  because  in  such  case  the  parties  are  not  ad  idem.
They  have  seemed  to  make  a  contract,  but  the  essential  ele-
ment of  certainty  is  lacking.  The  cases  previously  referred
to  where  a  telegram  making  an  offer  is  altered  in  the  course
of  transmission  and  the  offeree  accepts  it  as  altered  illustrate
this  principle^  In  Henkel  v.  Pape,^  the  parties  had  been  in
negotiation  for  the  purchase  of  fifty  rifles,  but  no  agreement
had  been  reached  when  defendant  telegraphed,  "Send  me
three  rifles."  The  telegram  as  delivered  read  "the  rifles,"
and  plaintiff  shipped  fifty  rifles.  It  was  held  that  defendant
was  not  bound  by  the  altered  telegram.
Where  the  contract  is  for  the  sale  of  a  certain  quantity,
and  the  seller  delivers  by  mistake  a  larger  quantity,  the  buyer
is  entitled  to  reject  the  delivery  and  cannot  be  compelled  to
select  the  quantity  agreed  upon  from  the  larger  mass.^  This
particular  kind  of  mistake,  however,  affects  the  performance
and  not  the  formation  of  the  contract.
