Ireceived so many interesting comments following my recent column on grilling (isn't anyone cooking indoors anymore?) that I asked some of the reader-writers for permission to publish their comments herewith.

* In your column you chose lump charcoal over briquettes or gas. But there's a fourth option. I use primarily wood, starting with two good chunks between which I place a handful of lump charcoal to help get the wood going. Over all, I stack short pieces of wood in a loose log-cabin fashion. One of the great benefits of this method is that the wood takes a little while to get going, during which some high-quality beer consumption and bird watching can take place. And during cooking, the flavor of the smoke really dresses things up. Wood is a fantastically primal method of cooking -- that's a significant part of its charm.

-- Alec MacLeod, North Orange, Mass.

Nice going. You've combined grilling and smoking very effectively. Have a beer for me.

* I agree charcoal is better than gas. However, my judgment is based on three very nontechnical perspectives.

1. When I go to bed, I don't have to remember if I turned off the gas or not.

2. I don't have to be a pest-control specialist to keep the squirrels from chewing through the rubber gas hose (wire coils can now prevent this frustrating event).

3. My Weber charcoal grill has outlasted the three gas grills that my children have given me for Father's Day over the last 20 years.

-- Jack O'Brien, Fairfax

Beware of well-meaning children.

* With your comment about water vapor being formed when gas burns, I now understand why the components of my gas grill rust out so fast. I barely get two years use out of "enamelized" grids and bars.

-- David Hanttula, Los Altos Hills, Calif.

Interesting, but I doubt if the rust is caused by water vapor from the burning gas. I'll bet you leave it outdoors without a cover.

* Here in the UK we tend to use butane gas, which I imagine burns hotter than propane. The burner flame heats a bed of pebble-sized lava bricks that then radiate heat upwards onto the meat placed above them. So it is unlikely that the water vapor would condense onto the meat. As a convert from charcoal I really don't miss the mess and long waiting time between lighting and cooking, and the food tastes just as good. Given the changeable English climate it is a good thing to be able to light the machine and be cooking within 10 minutes before the next rain shower comes along.

-- Bill Ferguson, Tenterden, UK

I agree. Gas grills are a lot more convenient than charcoal. And butane does indeed burn hotter than propane. But the water vapor is still there as vapor. It doesn't actually condense on the meat.

* You say that heat conduction plays little role in grill cooking. However, the cooking grate in my small Weber Q grill weighs something like 30 pounds, so it has a formidable heat capacity when you preheat the grill for 10 to 15 minutes. I think conduction from the grate plays a significant role, and I get good searing from that.

-- John Kent, Albany, N.Y.

Like most gas grills, your Weber Q has a porcelain-enameled, cast-iron cooking grate, which is indeed quite heavy. Charcoal grills generally have much lighter and thinner supports for the food, which then cooks almost entirely by convection and infrared radiation.

* I have known for years that it is better to grill steaks with charcoal than with gas. Thanks to your column I now know why. As a scientist (geologist) I always like to know why things work or don't work. But here's a problem. I have found that in grilling steaks I cannot get what I think of as the "charcoal taste" unless there is enough fat on the steaks. I understand that the taste is created by the melted fat dripping onto the hot coals, vaporizing and rising to contact the steaks. So now when I grill steaks, if they don't have enough fat I'll put a few pieces of beef fat on the grill. Anything wrong with that?

-- Bill Kirk, just outside of Clifton, Va.

Yes. What's wrong is your widely cited explanation of how the renowned charcoal-grilled flavor is produced. The flavor comes not from dripping fat but from the smoke produced by lump charcoal, briquettes and wood, but not by gas. The burned fat flavor you apparently like is quite different; it's acrid, sooty and unhealthful. In effect, you're cooking over flare-ups, which most grillers rightly knock themselves out to avoid. I suggest you do likewise.

* You indicated that for barbecuing the temperature should be between 300 and 350 degrees. I have read that some of the best barbecuers in the country use temperatures in the low 200s. Trying to walk in these rather large footsteps, last Sunday we smoked at 200-225 degrees, with great results. Since you are The Professor, I trust that your 300-350 is also true.

-- John Brandte, Deerfield, N.H.

Although many people use the terms "barbecuing" and "grilling" interchangeably, the cooking methods are not the same. Barbecuing for many hours at a very low temperature (and basting the food occasionally with sauce) is widely acknowledged to be an excellent way to cook ribs, brisket and roasts. But the typical backyard cook is more likely a griller who doesn't want to spend that much time, so the higher temperatures and shorter times are more commonly used for hamburgers, steaks and chicken.

* I'm going to switch to lump charcoal from the briquettes. I humbly admit I didn't know the difference. But I have one question. How do you ignite your charcoal?

-- Cheryl Haak, Bethesda

Several readers asked this question. I strongly recommend the charcoal chimney. You stuff newspaper in its bottom compartment, pour the charcoal into the top, and light the newspaper. After about 20 minutes, the lower half of the charcoal is glowing. You then dump the charcoal onto the grill's fuel bed and stir it around, so that the hot pieces will ignite the others. Chimneys are available in many places where charcoal is sold.

* Where can I purchase lump charcoal?

-- Ray Biagini, Chevy Chase (and many others).

Hey! Don't ask me. I live in Pittsburgh. But the Food staff says that it is available at many hardware stores and groceries, including Whole Foods. Read the label carefully and look for such words as lump charcoal, hardwood, mesquite wood, oak, maple, hickory or natural wood. For quality ratings and almost anything else you might want to know about the many brands of lump charcoal, go to www.lump-charcoal.com.

Robert L. Wolke (www.professorscience.com) is professor emeritus of chemistry at the University of Pittsburgh and the author, most recently, of "What Einstein Told His Cook: Kitchen Science Explained" (W.W. Norton, $25.95). He can be reached at wolke@pitt.edu.