Bottle bombs - Risk vs. Reward

When brewing goes smoothly it is wonderful and relaxing. When brewing goes wrong it is a time of irrational questioning panic and terrified paranoia. This story falls into the latter category. My brew buddy and I whipped up a batch of Belgian IPA from extract and went through the usual steps to get a fantastic batch of beer; or so we thought. Two weeks of primary fermentation and two weeks of secondary later brought us to bottling day.

Heating up water and 3/4 C dextrose we added it to the bucket and began supplying the wort. It smelled sweeter than usual but I ignored the quiet pleas of our beer and continued. We took a hygro reading and found that the beer was significantly higher gravity than it should be (1.048 instead of 1.018). In our desire to fix the beer we added it back to the small yeast cake in the secondary with the hope that it would ferment out. Two weeks later brings us to where we are now.

Things we did wrong:

1) Should have taken gravity reading before racking to the secondary.
2) In the event of failing #1, taken the reading before adding it to the dextrose

Questions:

1) Is this beer salvageable?
2) Even if it is salvageable, is the addition of the dextrose going to make it impossible for us to successfully carb this beer without either making it too flat or creating bottle bombs because the actual sugar levels are not known?

Regardless, it has been yet another learning experience.

Four weeks in your IPA was at 1.048? You don't mention where it started, but that's not a particularly good sign. Are you getting fermentation now in the second vessel?

The addition of dextrose won't do anything significant. It bumped your gravity up a point or two, but your yeast _should_ be able to take care of it no problem. That said, something is up with your yeast. That's the problem, not the dextrose.

Dextrose is just sugar. You add a bit at bottling to give the yeast a tiny bit more to eat so they make CO2 to carbonate your beer. I don't understand what you mean by "actual sugar levels are not known". That's what your hydrometer tells you.

The dextrose might have given your yeast the kick start they needed to finish the job. It isn't going to hurt anything, but I would leave it in your secondary for a few more weeks and check it again. You never know what could happen. Basically, you aren't going to have bottle bombs. Dextrose isn't some magical thing that only ferments when inside bottles; if any fermentation goes on in secondary I can almost guarantee that the dextrose will be the first thing to go.

I had a similar incident one time, but where did you take your gravity reading from? I took mine from the bottom of the bucket (after filling all the bottles) and got a really high SG like you did, but I think it was just because the solution of sugar that I added was so dense that most of it sunk to the bottom.