asked the President of the Board of Trade the minimum degree of purity of imported sodium hyposulphite above which the chemical is liable, to duty under Part I of the Safeguarding of Industries Act?

Sodium hyposulphite is dutiable when it ie of photographic quality, or of still higher quality. Photographic quality hyposul- phite is a well-known trade quality, but there is no fixed quantitative standard to which it must conform, and any hyposulphite which would be good delivery against an order for sodium hyposulphite, "photographic quality," is dutiable.

Is it the case then that the importer cannot know in advance whether he is liable to the duty and the imposition of the duty depends on the analysis?

Everybody engaged in the trade knows perfectly well what this trade term means.