8. Where a person is accused under section 482 of the Penal Code of using a false trade mark or property mark by reason of his having applied a mark to any goods, property or receptacle in the manner mentioned in section 480 or section 481 of that Code, as the case may be, or under section 6 of this Act of applying to goods any false trade description, or under section 485 of the Penal Code of making any die, plate or other instrument for the purpose of counterfeiting a trade mark or property mark, and proves- (a) that in the ordinary course of his business he is employed, on behalf of other persons, to apply trade marks or property marks, or trade descriptions, or, as the case may be, to make dies, plates or other instruments for making, or being used in making, trade marks or property marks, and that in the case which is the subject of the charge he was so employed and was not interested in the goods or other thing by way of profit on commission dependent on the sale thereof, and (b) that he took reasonable precautions against committing the offence charged, and (c) that he had, at the time of the commission of the alleged offence, no reason to suspect the genuineness of the mark or description, and (d) that, on demand made by or on behalf of the prosecutor, he gave all the information in his power with respect to the persons on whose behalf the mark or description was applied, he shall be acquitted.