Classification opinions
… This Classification Opinion applies to the complete system. Adoption : 1959 … 2. Fumigation chamber, mounted on wheels … etc., by the action of methyl bromide, prussic acid, etc. Adoption : 1961 … 3. Self-propelled machines for sweeping … pick-up broom, a dirt hopper and a fan to suck up dust. Adoption : 1964 … 4. Horns operated by compressed air, …