Fire of Isengard ?

[The Might]

I had the idea for this thread today as I was reading through LOTR...
It was the passage where the battle at Helm's Deep is described:

Even as they spoke there came a blare of trumpets. Then there was a crash and a flash of flame and smoke. The waters of the Deeping stream poured out hissing and foaming: they were choked no longer, a gaping hole was blasted in the wall. A host of dark shapes poured in.
'Devilry of Saruman!' cried Aragorn. 'they have crept in the culvert again, while we talked, and they have lit the fire of Orthance beneath our feet.

After I read this, I however remembered of something I read in The Hobbit, a description of the goblins living in the Misty Mountains:

Now goblins are cruel, wicked, and bad-hearted. They make no beautiful things, but they make many clever ones. They can tunnel and mine as well as any but the most skilled dwarves, when they take the trouble, though they are usually untidy and dirty. Hammers, axes, swords, daggers, pickaxes, tongs, and also instruments of torture, they make very well, or get other people to make to their design, prisoners and slaves that have to work till they die for want of air and light. It is not unlikely that they invented some of the machines that have since troubled the world, especially the ingenious devices for killing large numbers of people at once, for wheels and engines and explosions always delighted them, and also not working with their own hands more than they could help; but in those days and those wild parts they had not advanced (as it is called) so far.

As it is mentioned here, the Orcs had not reached such an advanced level in industry and science in the wild, however under Saruman's guidance at Isengard it might have been a very different story - in this case the Orcs might have learned how to use explosives, which were used for the "bomb" at Helm's Deep, and also for the machines in the caverns of Isengard.

Suddenly up came fires and foul fumes: the vents and shafts all over the plain began to spout and belch. Several of the Ents got scorched and blistered. One of them, Beechbone I think he was called, a very tall and handsome Ent, got caught in a spray of some liquid fire and burned like a torch: a horrible sight.

As we see some of these machines also used similar substances, perhaps also made by the Orcs.