law: Indian Trusts Act, 1882 
  83. Trust incapable of execution or executed without
  
  exhausting trust-property 
  Where a trust is incapable of being executed, or where the trust
  
  is completely executed without exhausting the trust-property, the trustee, in the
  
  absence of a direction to the contrary, must hold the trust-property, or so
  
  much thereof as is unexhausted, for the benefit of the author of the trust or
  
  his legal representative.
  Illustrations 
  (a) A conveys certain land to B- 
  "upon trust", and no trust is declared; or
  "upon trust to be thereafter declared", and no such
  
  declaration is ever made; or
  upon trusts that are too vague to be executed; or
  upon trusts that become incapable of taking effect; or
  "in trust for C", and C renounces his interest under
  
  the trust. In each of these cases B holds the land for the benefit of A.
  (b) A transfers Rs. 10,000 in the four per cents to B, in trust
  
  to pay the interest annually accruing due to C for her life. A dies. Then C
  
  dies. B holds the funds for the benefit of A's legal representative.
  (c) A conveys land to B upon trust to sell it and apply one
  
  moiety of the proceeds for certain charitable purposes, and the other for the
  
  maintenance of the worship of an idol. B sells the land, but the charitable
  
  purposes wholly fail, and the maintenance of the worship does not exhaust the
  
  second moiety of the proceeds. B holds the first moiety and the part unapplied
  
  of the second moiety for the benefit of A or his legal representative.
  (d) A bequeaths Rs. 10,000 to B, to be laid out in buying land
  
  to be conveyed for purposes with either wholly or partially fail to take
  
  effect. B holds for the benefit of A's legal representative the undisposed of
  
  interest in the money or land if purchased.