What constitutes a material alteration to a mortgage?

We agree also with her finding that the alteration was a material one and that as a result the mortgage could not be enforced. The definition of what constitutes a material alteration was considered by Lamont, J., in Gogain v. Drackett, (1909), 11 W.L.R. 643. He said at page 646: Any change in an instrument which causes it to speak a different language in legal effect from what it originally spoke-- which changes the legal identity or character of the instrument either in its terms or in the relation of the parties to it, is a material change, or technical alteration, and such a change will invalidate the instrument as against all the parties not consenting to the change. But at p.190 the author goes on: “It is not every change which will invalidate an instrument, but only a change which is material according to the principles above stated. In other words, any change in words or form merely, even if made by an interested party, which leaves the legal effect and identity of the instrument unimpaired and unaltered, which in no manner affects the rights, duties, or obligations of the parties, and leaves the sense and meaning of the instrument as it originally stood, is not material, and will not destroy the instrument or discharge the parties from liability thereon.