He smiled a little. He liked C4 explosive. It smelled funny but it does so much damage to people and property with so little effort and volume. Combine C4 with 650 tons of moving metal, like a passenger train, and one gets a good deal of bang for one's buck. One thing that was kind of a drawback was the blasting cap. And the funny smell. The smell that dogs could smell. Anywhere.
C4, or the common plasticized explosive stable enough to carry around in one's pocket, needed a impact AND heat to cause its ignition to accelerate exponentially. Otherwise it just burned like plastic, or when impacted, did nothing at all.

Carrying it around in his pocket all time did burn the skin on his leg sometimes, like when the zip lock bag melted or if the duct tape ripped the bag open.

All the C4 he had ever had used had a taggant added to it. All the C4 in the world, or as far as he knew, had a taggant added to it. It was a law or something. That is what the dogs could smell. Even when he wrapped it up will 6 layers of plastic, dogs could smell it.

If the talking dogs could lie, he could hide from their minds. Still, until dogs could verbalize that here was explosive nearby, he didn't care so much. He liked what the C4 could do. he fingered the two blasting caps he stole from the maintenance shed under Grand Central. He smiled.