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"Japanese Smoke Weapons" from Tactical and Technical Trends

The following U.S. intelligence report on Japanese smoke weapons is taken from Tactical and Technical Trends, No. 35, October 7, 1943.

[DISCLAIMER: The following text is taken from the U.S. War Department publication Tactical and Technical Trends. As with all wartime intelligence information, data may be incomplete or inaccurate. No attempt has been made to update or correct the text. Any views or opinions expressed do not necessarily represent those of the website.]


Japanese partiality toward the tactical use of smoke, and various materiels employed by the Japanese army's* "smoke" units have been discussed in Tactical and Technical Trends No. 21, p. 11; No. 27, p. 12. Recent reports on this materiel provides additional information in the form of descriptions of the Japanese frangible smoke grenade and the Japanese Type "99" self-projecting smoke candle.

The Japanese frangible smoke grenade is an iron-capped, spherical glass flask with a short neck and flat bottom. Measurements of the flask are:

Overall height     85 mm
Diameter (o.d.)65 mm
Circumference237 mm
Weight (empty)161.2 grams
Thickness of wall2 mm
Volume (to base of neck)150 ml
Opening16 mm

The closure consists of a red rubber stopper held under a red rubber washer within an inner iron crown cap, this being enclosed by a heavier iron outer crown cap.

Filling: The liquid filling of the grenade has the following properties:

Height of filling     31 mm
Volume69.6 ml
Weight118.0 grams
Specific gravity (calculated)1.69
   Titanium tetrachloride51.5%
   Silicon tetrachloride46.7%
   Titanium and silicon oxides, by difference1.8%

Functional Characteristics

The grenade is so shaped as to be easily thrown by hand. Titanium and silicon tetrachlorides are readily hydrolyzed by the moisture if the air, with the formation of the respective hydroxides and hydrochloric acid. The smoke produced is formed from the fumes of hydrochloric acid and the particles of hydrated titanium and silicon oxides.

Tactical Use

The smoke grenade is intended for screening operations. Though both titanium and silicon tetrachlorides are irritating to the skin as liquids, in ordinary field concentrations the smoke is hardly irritating enough to the respiratory system to cause coughing. Because of its size, the grenade used singly is ineffective for a continuous screen, but is intended for use at short-range such as screening the gun port of a pill-box or tank.

Comparison with Comparable U.S. Equipment

Titanium tetrachloride-silicon tetrachloride mixtures are not used by the U.S. Titanium tetrachloride alone, designated FM, is classed as limited standard for filling CWS smoke munitions but is not used as filling for frangible grenades.

The Japanese Type "99" self-projecting smoke candle has an outer cylinder, 8 inches in length, olive drab in color. The weight of the candle is 1283 grams (2.82 pounds) including a filling weighing 643 grams (1.41 pounds).

The starter mixture in a candle which has been examined was:

Potassium Nitrate     53.9%
Aluminum powder16.0%
Antimony Sulfide10.5%

The smoke mixture in the candle examined analysed as follows:

Hexachlorethane       46.5%
Zinc (metallic)20.4%
Zinc Chloride18.3%
Zinc Oxide14.8%

Evidently this self-projecting candle can be used for setting up an advance smoke screen in much the same manner as is accomplished by mortar or artillery shells, except that the range is shorter. There is a delay train in front of the starter mixture. This delays ignition of the candle for a definite time after it has been propelled from the outer case. The delay time has not been determined.

There is no U.S. munition comparable to the Japanese Type "99" self-projecting smoke candle. In tactical use it can be compared to the M-8 HC smoke grenade for very short range and to the small HC filled rockets, mortar shells and the 75-mm base ejection shell.

*To allay suspicion, all chemical units in the Japanese army are referred to as "smoke" units.


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