This is an Fisher Scientific ultrasonic cleaner. Ultrasound is the spectrum of sound waves that are two high for human ears to detect. The machine generates ultrasonic waves to clean objects placed inside. “Solid State” refers to the type of generator producing the sound waves. All ultrasonic cleaners manufactured today are solid state.
An object would be placed into the tank on top, together with water and usually some kind of cleaning agent. The energy of the waves in the water is extremely intense (20,000 lbs per square inch), but they are too small to damage the object and only clean away the dirt and detritus that has accumulated on the surface. The higher the frequency of the waves, the greater the ability of the waves to clean away very small particles. Ultrasonic cleaners are good for small objects like jewelry, small mechanical parts, lenses, and some electronics. I could not find any information on this specific object, so I can’t say what it was used for, but the tank still smells strongly of some kind of cleaning agent.