A steam generator supplied with distilled water enables, with steam bubbling into the sample, an extraction of volatile acids, alcohols, etc. (according to the selected program). A rectifying column with Raschig rings separates the steams and prevents the distillation of the lactic acid. A coil cooler, equipped with a special tube for connection with the air to equilibrate pressure, condenses and collects all the steams. The distillate comes out by a glass tip and is collected in a volumetric flask, placed on a weighing scale that detects automatically the end of the distillation according to the selected program.