I can only speak about the observed ADC ops in Chicago.

The aircraft is a all white KC-767 or KC-46 type twin engine, with no passenger windows. The only markings are the minimum size 'N' numbers which are not discernible at spotting scope maximum magnification 50-60X. No tail logo.

Roughly from Wiki. The payload is 65,000 pounds which is about 8,000 gallons. Nozzle locations are 4 nozzles, ADC plumes not in line with the engines.

Chemical formulation? Who knows? Safe innocuous chemical markers for tracking and efficacy tests? Behavior modification chemicals? Biologicals like a flu virus? Maybe some chemical to receive HAARP or change weather patterns.
ADC ops over Chicagoland all had 'events' in the same time period; New Rush hospital infectious bioterrorism pandemic wing, racial uprising, flu outbreak/vaccine push, land hurricane weather system, secret terrorist interdiction over Chicago, in that same order.

One aircraft seemed to do a 300 sq mi perfect job of dispersion at some pre-designed density only the engineers knew. The final haze was a slightly translucent blanket at altitude, the haze continued to descend. If a biological were used, a density of 1 'bug' per cubic foot could be attained from 35,000 feet to the ground, with the payload available(300 sq mi).