Tetrachloroethylene, also known under the organized name tetrachloroethene, or perchloroethylene -LRB- `` perc '' or `` PERC '' -RRB-, and umpteen additional names, is a with the formula Cl2C = CCl2. It is a pale fluid widely for solid cleaning of fabrics, hence it is sometimes called `` dry-cleaning fluid . '' . It a dessert odor perceptible by most people at a concentration of 1 part per million -LRB- 1 ppm -RRB- .