11. Where a witness, on cross-examination as to a former statement made by him relative to the subject-matter of the case and inconsistent with his present testimony, does not distinctly admit that he did make the statement, proof may be given that he did in fact make it, but before that proof can be given the circumstances of the supposed statement, sufficient to designate the particular occasion, shall be mentioned to the witness, and he shall be asked whether or not he did make the statement.

R.S., c. E-10, s. 11.