I read the article on the Chinese Box method of roasting a pig in a recent Post Food section. I'm thinking of cooking a roast pig at a big family reunion and I'm investigating various methods. What other methods are possible and practical?

Well, you could sequester a live pig in your house and burn it down, as in Charles Lamb's classic essay, "A Dissertation Upon Roast Pig." Ah, but you said "practical," didn't you?

I don't often write about cooking per se, but this is really a scientific question about how to put a lot of heat into a lot of pig. If I may lapse into geekspeak, it's an exercise in the transmission and absorption of thermal energy. (Can you think of a less romantic way to talk about cooking?)

The Chinese Box, as you may recall, is a sheet-metal-lined plywood box in which you place the pig; on the steel top, you pile hot coals. It was invented by a Cuban American man named Roberto Guerra Sanchez, who, as the owner of a small restaurant in New Jersey, was intrigued with the American broiler or salamander, in which the source of heat is above, rather than below, the food being cooked. Several years of experimentation led him to invent the "Chinese Box," or Caja China (CA-hah CHEE-na) in Spanish, which combined the broiling method with an enclosure reminiscent of the pit in which Cubans traditionally roast pigs and other large meats.

But why "Chinese"? It's just a joke, having nothing to do with China. In Cuba, anything intricate or ingenious is referred to as Chinese or Chino(a). A seriously ill person, for example, is said to be beyond the help of even un medico chino, or a Chinese doctor. Hence, the roasting contraption was dubbed la Caja China.

Placing the hot charcoal above instead of below the food may strike you as counterintuitive, because heat rises -- doesn't it? Well, not exactly. It's not heat that rises; it is hot air that rises through cooler air because, having expanded, the hot air is less dense. Hot air carries its burden of heat to higher elevations by the heat-transfer mechanism known as convection. (A convection oven supplements the vertical transfer of heat by fanning the hot air in all directions, so it contacts all sides of the food and speeds the cooking.)

But the Chinese Box doesn't cook by convection; it cooks primarily by radiation. Infrared radiation is pure radiant energy, emitted in all directions from everything in the universe except black holes, which presumably are of minimal concern at a backyard barbecue. The metal lining of the Chinese Box reflects the infrared radiation throughout the enclosure, like microwaves in a microwave oven, so all surfaces of the pig are heated, not just its top.

Infrared radiation is often called heat radiation, but it isn't heat until it strikes an object whose molecules absorb it and turn it into heat by becoming more agitated. That's what heat is: the agitation of molecules. I prefer to call infrared radiation "heat in transit" -- radiant energy, sent out at the speed of light from one object to another, where it receives a literally warm welcome.

Let's look at the thermodynamics of other ways to roast a whole pig, hog or, in some places, hawg, by barbecuing, barbequeing or BBQ-ing it, no matter how we spell it.

Different cultures, notably Hawaiian, Cuban, Italian and Puerto Rican, have their own traditional ways of roasting a whole pig. (When I lived in Puerto Rico, I frequently stopped at one of the roadside, glass-enclosed carts selling pieces of lechon asado, or roast pig. I always asked for un pedazo tostadito, a crisp piece of the wonderfully toasted skin, to be hacked off by el patron with his machete.)

The best pig-cooking methods involve either a pit or a spit. (Indoor ovens are disdained by true barbecue buffs.) In the pit method, the pig is first butterflied, whereas in the spit method it is roasted whole-hog.

The traditional Cuban method begins by building a roaring charcoal fire in the bottom of a rectangular pit or dugout. When glowing brightly, the coals are raked out of the center into the four corners of the pit. The pig is then centered on some kind of grid, so as not to be directly above the cornered coals. It is thus out of the path of vertically rising hot air (convection heating), but is still bathed in infrared radiation from the coals. The objective is to cook it more slowly than if it were placed directly above the coals, because slow cooking produces tender, juicy meat. The Chinese Box is essentially a portable pit, sold to Americans who would prefer not to dig pits in their lawns.

On a spit, the pig is rotated continually in front of a wood or charcoal fire, but never directly above it unless one wants a pink pig in a black blanket. Again, because the meat is not directly above the fire it cooks primarily by radiation. In slow barbecuing, the surface heat from absorbed infrared radiation has plenty of time to work its way into the meat by conduction. Conduction is the third way in which heat can be transmitted, in addition to radiation and convection.

How does one serve a whole pig? At a party in Puerto Rico, I watched as the famous singer Lucecita Benitez wielded a machete to reduce an 80-pound lechon asado to plate-sized portions. It was great fun when she handed me the machete to take a few whacks of my own, during which time I utilized my hacker's perks to snatch a few choice pedazos tostaditos.

LABELINGO: Perspicacious reader Nancy Shapiro of Rockville purchased a cherry-and-chocolate confection from the Cherry Basket in Bethesda. The label promises "No artificial colorings, flavorings or preservatives," but among the listed ingredients is "vanillan (an artificial flavor)." Vanillin is defined as an artificial flavor by the FDA.

(Have you noticed any silly things on food labels? Send your Labelingo contributions, along with your name and town, to Food 101, Food Section, The Washington Post, 1150 15th St., NW, Washington, D.C., 20071 or to the e-mail address below.)

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, hardcover, $25.95). He can be reached at wolke@pitt.edu.