As a professor, I've always told my students that there is no such thing as a stupid question. If there is something you want to know, then you must have a good reason for wanting to know. It shows you're thinking.

But now that I'm a food columnist--how can I put this?--I do get an occasional question that is, shall we say, slightly out of left field. Here are a few of those less-than- earthshaking--but far from stupid--questions that have been languishing in my in-box.

I'm surprised that most bottled spices and herbs in the supermarket are not labeled with a "best if used by" date. What is their average shelf life? Also, we leave them in our non-winterized summer cottage that stays at or below freezing much of the year. Will they survive freezing temperatures?

Bottled herbs and spices are thoroughly dried, and spoilage bacteria can't live without water, so if tightly closed they'll last indefinitely. That's (duh!) why the manufacturers dry them. Also, things that are completely dry can't freeze; it's the water in foods that freezes. So your frigid cabin is irrelevant. But many spices lose their potency over time, so be a sport and spring for fresh ones every couple of years.

I have observed an interesting phenomenon with bottles and cartons. When I pour out the "last" drops, no matter how long I invert the container I can always come back later and pour out a bit more liquid. What's going on?

I welcome this opportunity to apply my scientific reasoning powers to a problem of utter insignificance.

Discounting the possibility that someone is playing tricks on you, I would guess that some drops of liquid are adhering to the inside surface of the container because they encounter microscopic rough spots that trap them and prevent them from sliding any farther. But when you return the container to its upright position, they can slide back down, joining their brethren to form a pool. This pool now has more mass than any individual drop had, and it will roll down under the force of gravity when you invert the container again.

If this is really keeping you awake at night, move to Jupiter, where the force of gravity is 300 times stronger than on Earth and will easily overcome any rough spots.

The last time my wife made lasagna, she put the leftovers in the refrigerator covered with aluminum foil. When she took it out of the fridge to reheat, we noticed that wherever the foil touched the lasagna there were tiny holes in the foil. Is something chemical going on? If so, what is the lasagna doing to our stomachs?

As you feared, the lasagna is actually eating holes in the metal. (No reflection on your wife's cooking.) Aluminum is what chemists call an active metal and is easily attacked by acids such as the citric and other organic acids in tomatoes. In fact, you shouldn't cook tomato sauce or other acidic foods in aluminum pots because they will dissolve enough metal to make them taste metallic. Stomach linings, on the other hand, contain a much stronger acid (hydrochloric) than the acids found in any foods and are even immune to office coffee.

After I roast a chicken there are all these gooky drippings in the pan. Can I use them for anything?

No. If you have to ask, you don't deserve them. Pour off the fat, scrape the rest of the drippings into a jar and ship them to me by overnight express.

Seriously, they're marvelously flavorful juices and gels, and it would be a crime to discard them. Make gravy. I have often thought that if I were a king or emperor, I would order my cooks to roast a hundred chickens, throw them to the peasants and serve the combined drippings to me on a silver platter along with several loaves of crusty French bread.

I like to try new products and bought a plastic-wrapped package labeled "Souse" in my neighborhood supermarket. The package didn't include even the simplest cooking instructions, nor could I find any recipes in any of my dozen-plus cookbooks. So I sliced it, coated it with cornmeal and tried to brown it in a frying pan, as I do scrapple. The result was grease soup. What went wrong?

Just because souse and scrapple have funny names and come in refrigerated rectangular blocks doesn't mean they're related, except for their porcine parentage.

Scrapple is a chilled mixture of pork pieces, cornmeal mush and spices, while souse is made from--are you ready?--scraps of meat from a boiled pig's head and sometimes from the feet and ears as well, spiced and seasoned and all held together by the gelatin that forms from collagen in the head. When you heated it, it was like trying to fry Jell-O. Also known by the appetizing name of headcheese, souse is meant to be eaten cold (if at all).

Sticks of butter stored in a covered glass butter dish in the butter compartment of our refrigerator develop a dark yellow, slightly rancid-tasting skin. Is there any way to prevent this?

You probably think you're doing everything right, don't you? Well, the worst place to keep butter is in a butter dish, and the worst place to keep the butter dish is in the butter compartment of your refrigerator.

Butter dishes were invented to facilitate serving, not preserving. Because they're not airtight, the butter can pick up off flavors from other foods in the fridge, and butter is very good at that.

Butter compartments should be banned. They have little heaters in them to keep the butter at a slightly warmer temperature than the rest of the fridge to make it easier to spread. But the warmer temperature speeds up oxidation of the fat, otherwise known as rancidity. I keep my butter in the freezer compartment, tightly enveloped in plastic wrap. Yes, it's hard as a rock when I go to use it, but a sharp knife can whack off a piece that will warm up rather quickly.

See? "Stupid questions" are often the most fun. Keep 'em coming.

Robert L. Wolke is professor emeritus of chemistry at the University of Pittsburgh and the author of "What Einstein Didn't Know--Scientific Answers to Everyday Questions." Send your food or cooking questions to wolke@pop.pitt.edu.