(2) of section 19 reads thus : " (2) A vendor shall not be deemed to have committed an offence if he proves (i) that the article of food was purchased by him as the same in nature, substance and quality as that demanded by the purchaser and with a written warranty in the prescribed form, if any, to the effect that it was of such nature, substance and quality; (ii) that he had no reason to believe at the time when he sold it that the food was not of such nature, substance and quality; and (iii)that he sold it in the same state as he purchased it : Provided that such a defence shall be open to the vendor only if he has submitted to the food inspector or the local authority a copy of the warranty with a written notice stating that he intends to rely on it and 819 specifying the name and address of the person from whom he received it, and has also sent a like notice of his intention to that person.