So Ariadne, a couple follow-up questions then:
-Would a cannon ball made from NJ bog iron hurt less if it hit you in the stomach, than from one poured from, say, Pennsylvania ore?
-Does your statement about the "impurities" and "structural irregularites" inherent in our bog iron translate to the general statement that materials and products cast from bog iron ore in 19th century NJ were useless in most applications?
-Can processing techniques indeed improve upon some of the negative qualities? Do you think some furnaces may have indeed perfected techniques that improved their products greatly?
-Were there any products fashioned out of bog iron ore in NJ during the 19th century of such a qualtity that they were (and still are today) admired for their strength, durability, and workmanship? Or was everything just useless junk that broke or shattered easily.
You seem to be taking this personally.
Bog iron is more brittle than other forms of iron. Hence, there is a larger chance that a cannon made from bog iron would explode vs. a cannon made from Pennsylvania iron. A cannon ball made from either form of iron is going to do the same damage.
I don't think that anybody has said that bog iron products were useless. Brittle, yes. Inferior to Pennsy iron that was stronger, yes. But, how strong does a window sash need to be? How strong does a fireback need to be? Obviously there are applications that bog iron would be just as good for than any other form of iron. It's all a matter of how much stress the finished product was put under.
I am sure that, had the Jersey furnaces stayed in business longer, there would have been more and more advances to improve the quality of the finished product. Most of these advancements were made in forge technology rather than furnace technology, with the main exception being the development of the hot blast technique.
Jersey Furnaces died because they couldn't compete with Pennsylvania furnaces. Pennsylvania furnaces were larger[1], and therefore could produce more. Pennsylvania had the benefit of a better rail network. Coal was easier to get than charcoal, and the iron in the Pennsylvania mountains was of a higher quality (and probably cheaper to mine) than bog iron.
[1]
Making Iron & Steel: The Historic Process, 1700-1900 by Jack Chard, North Jersey Highlands Historical Society, 1995 p.6