FIELD: gas analytical methods. SUBSTANCE: chemical activity of air and carbon dioxide is determined on a carbon product in the same test, activity of air being determined first and that of carbon dioxide being determined automatically after air analysis is terminated. Black carbon index is evaluated by collecting and weighing black carbon dust. Device consists of vertical pipe heater with gas inlet and sample holder for carbon product. The latter freely hangs over from weighing arrangement and drops down into pipe heater. Holder is provided with one or more thermal elements for recording temperature of carbon product. EFFECT: improved analytical procedure. 4 cl, 8 dwg, 1 tbl
