Chucku, I should have gotten the reference, but this was a post in what I thought was a short lived thread. Like I say above my response got moved here. Since plenty will read it (here) and think I was talking out my hat, I need to reply. So, apologies to Iolite for this somewhat off topic tobacco related post.
http://www.cnn.com/US/9802/04/minnesota.tobacco/
"Pointing to internal company documents, Channing Robertson, testifying on behalf of the state Wednesday, said that in 1965, scientists at R.J. Reynolds, trying to find out why their Winston brand was losing ground to Philip Morris' Marlboro brand, discovered that Marlboro contained ammonia compounds.
Robertson, a Stanford University professor of chemical engineering, said ammonia increases the nicotine potency of cigarettes by increasing the amount of nicotine contained in the vapor smokers inhale.
In the 1970s, Reynolds started adding ammonia and "slowly but surely, everyone fell in line," he said.
By 1989, documents showed that tobacco companies were using more than 10 million pounds of ammonia compounds each year, Robertson said."
I think I googled 'ammonia added to tobacco' and a few listings down this confirmed what I had heard.
And yes, I imagine ammonia is a by product of the curing, but this is added ammonia, basically fertilizer grade ammonia added as a nicotine booster. Nice guys.
You know the reasons. 
