Smoke of a yellowish brown color was generated in considerable volume for a period of 4 minutes. A small cloud of vapor at the finish usually lasted for another half minute. Figure 15 shows the candle, smoke substitute, in operation.

These candles could be fired either singly with the scratch block or as a group with electric squibs. When fired individually, the adhesive tape from the cover of the candle was removed and the candle was placed in an upright position on the ground.

Fig. 16.—Illustration of electrical method of firing candles.

1. Candle. 3. Cardboard diik. 5. Squih. 7. Lead wire.

8. Exploder

Fig. 15.—Candle, smoke substitute, in nitration.

After the tape was removed from the match head; the scratch block was drawn across the match head. When fired ax a group, the adhesive tape from the cover of the candle and the cover were removed, also the scratch block and tape, exposing the match head. The plug from the base of an electric squib was removed and the squib with base (open end) was securely taped against the match head.

The candles were then connected in a series and attached to a blasting machine (see Fig. 16). The number of candles that may be fired electrically is limited only by the capacity of the exploder or blasting machine used.

The candle, smoke substitute, was painted black. Paint wa* applied by dipping the candle in asphaltum paint for the purpose of protecting

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