TYPE OF AGENT – Smoke composition (pyrotechnic)

NAME (NATO) – HC

NAME (COMMON) – HC Mixture

DATE OF DISCOVERY – 1926 (1915)

MOLECULAR WEIGHT – 236.74 g/mol (Hexachlorethane)

PHYSICAL STATE @ 20° C. (68° F.)  – Solid

FREEZING/MELTING POINT – 184° C (363° F.) (Hexachlorethane)

BOILING POINT – 186° C. (367° F.)

DECOMPOSITION TEMPERATURE – 185° C. (365° F.) (Sublimes)

SOLID DENSITY – 2.0 g/cc

VAPOR PRESSURE (mm/Hg) – 0.4 mm/Hg @ 20° C.

ODOR – Acrid, suffocating smoke

APPEARANCE – Colorless crystals

COMPONENTS OF MIXTURE – 36% Zinc (Dust), 44% Hexachlorethane, 10% Ammonium Perchlorate, 10% Ammonium Chloride

PERSISTENCY – Only while burning

RATE OF ACTION – Rapid

SYMPTOMS (PHYSIOLOGICAL ACTION) – Stinging and redness of the eyes, Lung irritation and cough

TREATMENT – Remove from exposure

DURATION OF EFFECTIVENESS – Several minutes

PROTECTION – None normally, Gas mask for extended exposure

DECONTAMINATION – Washing with soap and water

USE – Burning-type smoke munitions

    Originally invented by Captain Berger of the French Army this agent was adopted and modified by the US Military in 1917. The as adopted US Military smoke mixture, referred to as the B.M. Mixture, was developed in 1917. The mixture consisted of (by weight) 35.4% Zinc Powder, 41.6% Carbon Tetrachloride, 5.4% Ammonium Chloride, 9.3% Sodium Chlorate, and 8.3% Magnesium Carbonate. The use of Carbon Tetrachloride as a major component of the B.M. Mixture was considered a drawback, but the formulation was considered satisfactory for combat use during WWI. In the post-war period, the HC formulation was developed and adopted as standard by the US Military in 1926. Burning 3.4 g (0.12 oz) of HC mixture will produce 28.3 m³ (1,000 ft³) of standard smoke.