34. A contract under seal is necessary at common law -

(a) Where the promise is without consideration.

(b) Formerly, corporations could only contract under seal, with some few exceptions; but with us they can make contracts which they have the power to enter into in the same manner as a natural person, unless restricted by charter.

(c) Conveyances of land are in most jurisdictions required to be under seal.

It is usually a matter of choice with persons whether they will contract by word of mouth or simply in writing, or in writing under seal; but in some cases, either at common law or by statute, it is necessary to employ the form of a deed.