asked the Prime Minister whether, having regard to the urgent necessity of securing for laboratory and other purposes a sufficient supply of the different kinds of glass used in the manufacture of optical and other instruments, and having regard to the importance of encouraging the production in this country of such glass, he will arrange for the introduction at an early date of a Bill prohibiting for a time, except under special licence, the importation of such varieties of glass and of such scientific instruments as may or can be produced in this country?