Description: These grenades are recognizable mainly as round glass bowls filled with HCN. They differ in minor details.

1. The copper stabilized type is round bottomed whereas the 172 B-K and 172 C-K have flat bottoms.

2. The copper gives one a yellow tint while the other two appear to be light green.

3. The copper stabilized type has one moulded ring around the outside instead of two as the others have.

4. The copper stabilized type is closed by a crown cap over a cork stopper and the other two are closed by a crown cap over a rubber washer.

5. The copper stabilized type is carried in a sheet metal container and the 172 B-K and 172 C-K are carried in cardboard containers.

The grenades contain 12.2 oz. of liquid which is about 85% hydrocyanic acid. This is a very strong systemic poison.

Operation: The grenade is thrown and on impact the glass will break releasing the HCN. This gas is swift and deadly if inhaled. In such quantities the gas is exceptionally nonper-sistent so these grenades are designed for use in small closed spaces such as pillboxes or tanks.

Description: This grenade is a flat bottomed spherical made of clear glass. It has a short neck closed by 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. The filling is a mixture of titanium and silicon tetrachloride which will be hydrolyzed by the moisture of the air, with the formation of hydroxides and hydrochloric acid.

Operation: The grenade is thrown and on impact the glass bottle breaks releasing the fluid and producing smoke. It is intending for use in screening operations. Though the filler is irritating to the skin as a liquid, in ordinary field concentrations the smoke is hard-ly irritating enough to cause coughing.

Figure 181 – Frangible H.C.N. Grenades and Frangible Smoke Grenades.