A professional who tends machine that mixes ground phosphate with sulfuric acid to produce superphosphate. Respnsibilities include:

• Pulls levers to open storage tank or hopper and admit materials into weighing hopper of machine.
• Pulls lever to open bottom of weighing hopper and dump materials into mixer.
• Tests sulfuric acid to determine if strength and temperature meet specifications, using hydrometer and thermometer.
• Starts mixer and blends materials for specified time.
• Pulls lever to dump mixed materials into storage pit.
• Records weight of materials mixed.