The stories range from a lovers' quarrel to a Frenchman spilling kerosene on his jacket, but the result in all versions is the same: A petroleum-based fluid is spilled on a greasy fabric and -- presto -- it's clean. That was the beginning of "dry" cleaning. It is dry only in the sense that a solvent other than water is used. When the spillage occurred is unclear, but the first known dry cleaning establishment opened in Paris in 1840. Not for more than a half-century did the technique become popular in the United States. For the first few decades, clothes were dry-cleaned with substances such as kerosene, gasoline and benzene. These cleaned the clothes but had a less fortunate side effect. "The shops tended to blow up a lot," says Steve Risotto, executive director of the Center for Emission Control, a private group that helps the industry to deal with safety and environmental issues. "They were out in the boonies, because you couldn't have them in the town because they burst into flames on a regular basis." By the 1930s, perchloroethylene or PERC, for short -- a synthetic compound that doesn't burn -- came into use. The terror about fire subsided, and dry cleaning stores moved into the heart of populated areas. Then the terror about cancer began. According to various studies conducted from the 1970s onward, mice fed large amounts of PERC or breathing its vapors had a high incidence of liver tumors. This discovery was alarming because dry cleaning waste then was placed in landfills and dumpsters, and it oozed into groundwater and soil. Environmental Protection Agency (EPA) regulations gradually tightened, culminating in a law that took effect a year ago, requiring all dry cleaners to have "dry-to-dry" cycles, meaning that clothes are placed in the machine dry and come out dry. Almost all PERC, liquid and vapor, is recaptured. Clothes go into a washing machine that resembles an enormous dryer, with 20 to 100 pounds of swirling clothes visible through a circular window. Beforehand, they are checked and treated by hand for stains. If the fabric is unusual or known to be troublesome, the label is checked to verify that the manufacturer has deemed the item safe for dry cleaning. Any stain thought water-soluble must be removed by spot cleaning before the item goes into the dry-cleaning machine. If not, the stain might be permenent. "A sugar stain may not show," Risotto says. "You may not see it, but once you throw it in a dry cleaning machine, it oxidizes and turns brown. And you've got a stain where you didn't have a stain. So it's a real art where a dry cleaner can identify stains and get them out." If it's a greasy stain, water won't help, but PERC will. It dissolves grease. The action, says Klaus Theopold, an inorganic chemist at the University of Delaware, is similar to what happens to a sugar cube in water. The attractions between sugar molecules are not as strong as those between molecules of sugar and of water. So the water effectively removes sugar from the cube, dissolving it. Similarly, PERC pulls greasy stains out of fabric. The grease in the solvent is removed by filter and by distilling the perc. In other words, the dirty PERC is boiled, and the vapors are condensed back into a clean liquid. Despite the name, a small amount of water and detergent are mixed with the PERC, typically about 1.5 percent of the total, to dissolve water-soluble stains. Before clothes are removed from machine, the washer becomes a dryer. Hot air is blown through the compartment but, instead of being vented outside, the airstream goes through a condenser that liquifies PERC vapors and returns them for reuse. After washing, clothes are steamed and ironed. Although the dry cleaning machine removes most of the PERC from the clothes, a small amount remains, and there is debate about whether this should be of concern. According to a newsletter from the International Fabricare Institute, the trade association for dry cleaners and launderers, "solvent retention in dry-cleaned articles is very small. Polyester/cotton blends, sleeping bags, down coats and shoulder pads tend to retain more solvent than other types of items." Risotto, whose organization works with PERC producers, said no odor should remain in clothes when you pick them up. The smell, like that inside dry cleaning establishments, is a "sweet, ether-like odor." Recapture and recycling of PERC is so effective now, according to James Kenney, an EPA environmental engineer and enforcement officer, that between 95 and 99 percent is retained. Tighter EPA regulations have led to a 50 percent decrease over seven years in the amount of PERC used. That has driven down the number of companies that make it to three in the United States: Dow Chemical, PPG Industries and Vulcan Chemicals. The greatest risk is to dry cleaning employees, who periodically must wear a badge that measures PERC exposure. Companies also must check for leaks in and around the machines. Of the approximately 30,000 dry cleaning and laundering companies in the United States, about 8,000 belong to the International Fabricare Institute (IFI), which provides various services to members and the public. Sleuthing is one service. When a piece of clothing is damaged or destroyed at the dry cleaner, IFI employees, use various chemicals such as PERC, standard commercial detergent and bleach, in trying to determine fault. Spots of bleached-out fabric around the collar, for example, can mean that the customer used a hair spray containing bleach, thus creating the damage. A blue-and-white pattern that has bled blue into white is tested separately with PERC and detergent. If either removes the blue dye, the fault is the manufacturer's for producing a garment basically impossible to clean without damaging it. The institute also tests fabrics for clothing and textile manufacturers. Swaths of materials are subjected to pounding, twisting, friction and weight tests to determine how much torture they can withstand before being damaged. CAPTION: THE PROCESS A modern dry cleaning machine is a combination washer and dryer. It also includes extra plumbing that cleans the cleaning fluid and recycles it for use in the next batch. WASH CYCLE 1. Between 20 and 100 pounds of clothes or other fabrics are loaded into the washer and tumbled. 2. Solvent (98.5 percent perchloroethylene and 1.5 percent water with detergent) is pumped from a tank, through a filter and into the washer. 3. As the load tumbles, solvent is pumped out, through a button trap and back into the tank. Solvent circulates continuously as the load is washed. DRYING CYCLE 1. After liquid solvent is drained, a fan pulls vapors from the washer and pushes them through a lint filter. A chilled condenser causes solvent vapors to turn back into liquid, which is piped to the water separator. 2. A heater warms air moving into the washer. SOLVENT RECLAMATION 1. At the end of a wash cycle, dirty solvent is boiled, and the vapors are converted back to liquid in a condenser. Grease and other dirt remains behind and is disposed of. 2. Condensed solvent goes through an apparatus that removes water and returns clean solvent to a tank from which it can be pumped for another wash cycle.