barter vs exchange of contracts

barter

noun
  • The goods or services used in such an exchange. 

  • An exchange of goods or services without the use of money. 

verb
  • To exchange goods or services without involving money. 

exchange of contracts

noun
  • The act of exchanging contracts. 

  • The point or stage at which a conveyancing contract comes into existence between negotiating parties for the carrying out of a disposition of an estate in land; usually requiring the payment of a deposit. 

How often have the words barter and exchange of contracts occurred in a corpus of books? (source: Google Ngram Viewer )