How strong of a coffee can I make?

I did this any number of times when I worked by myself in an office every weekend, especially the 12 hr days. It was truly awful coffee, and it started me down the road to a lot of heartburn. However, I didn't just get a jolt, I didn't just shake - I *vibrated*, and the whole world vibrated with me.

Yes, the strength would increase by percolating coffee through coffee. You could also just brew regular coffee and boil it down to mud. You could also grind the beans finer, compress the grounds into a sort of puck and force the hot water through it under pressure, to create this mysterious super-coffee to which you refer, which is also known as espresso - the only way you're going to get something palatable (there is no method of pleasurably concentrating commonplace drugs that hasn't already been done, my friend). Yes, there are always limits to how much of a particular solute you can dissolve in a given solvent. Past that stuff starts to precipitate out spontaneously. Your coffee would probably hit the saturation point with solutes other than caffeine, which is a minority constituent of coffee. If you wanted super-caffeinated coffee you could, like dissolve a no-doze in it or something. Frankly, if espresso isn't doing the trick for you, you need to seek help, not stronger coffee.

CoffeeFilter.... heh.

For a great caffeine kick try a double espresso topped with a filter coffee. Just like americano but you are using coffee from a French Press instead of water to top your cup up. Tastes great as well! As a side note I've been experimenting with putting dried chilli in with my coffee for blow your head off espressos. Deeply satisfying and an experience well worth trying imo.

I'm not sure where people are getting the impression that espresso has loads of caffeine. Because http://coffeetea.about.com/library/blcaffeine.htm - 3-4X by volume. Espresso brews a larger amount of coffee per volume of water under pressure, which factors contribute to a higher concentration of caffeine as well as other constituents.

1,3,7-trimethyl-1H-purine-2,6(3H,7H)-dione () has a solubility in water of 180mg/mL at 80C. This is probably hotter than you want to drink your coffee, but it does suggest an upper bound to exactly how much caffeine you could theoretically get in the water. I don't think you'll get that from straight hot water extraction; If you want the highest possible caffeine concentration, you'll want to brew a large amount of coffee, then boil off the water. This will, of course, be both extremely unpleasant to taste and toxic. LD50 in rats is 192 mg/kg; doses in excess of 400mg in humans will cause adverse effects. If all you're interested in doing is extracting the caffeine, you're better off using a different solvent, or just buying No Doz.

Ah, now I see that you have no real practical interest in this question. Never mind! I hope it helps someone else who is looking for the delicious hum of hypercaffeination and smooth, tasty coffee-crack. FYI, for those people: espresso has less caffeine than a cup of regular drip coffee. Likewise, dark roasts have less caffeine than lighter roasts -- the more heat the bean is exposed to, the less caffeine there is in the resulting bean. I always had a hell of a time getting kids studying for exams to understand that the fact that their coffee tasted stronger did not mean it was stronger.

(http://coffeegeek.com/guides/turkishcoffee)

I realize that this isn't truly answering the question because I can't tell you how much caffeine will be in your coffee, but I will tell you that if you do this you will have a pot of disgusting rancid bilgewater. I Other people have already tried this so you don't have to.