These slick, gray bodysuits were the second skins of Fremen-and of all those with good sense who had occasion to venture into (he Arrakeen desert. An unprotected human, without ac cess to a staggenngly large water supply, could last no more than a day on the sands, one wearing a stillsuit ot Fremen manufacture, however, could keep water loss under fifteen milliliters per day The less efficient versions of the suits produced in village factories by the Arrakeen peons were greatly inferior and offered no such level of protection. Stillsuits were an invention-of-necessity developed after the Zensunni nomads were transported to Arrakis Not even on Ishia, an earlier stop m the Zensunni's migrations, had water conservation been so essential that permitting any bodily moisture to escape could be fatal. Practices which had made life possible on that and planet (though far less snLLSurr 481 and than Arrakis) were simply too inefficient for the new environment, and the stillsmt was one of the first adaptations made The fabric itself made the suits effective Its invention was a tribute to the Fremen's ability to "cross-use" technology The Zen-sunm had been used as laborers of many different types during their generations of wandering and had retained the knowledge of the various kinds of devices and machinery they had operated One such machine, a cryogenic separator, had been used on a number of worlds for drawing oxygen and other gases from a planet's atmosphere The Fremen remembered the technique and applied it to the manufacture of sailcloth The fabric, a microsandwich in its completed form, was produced in layers The innermost la>er consisted of a porous membrane allowing the free passage of perspiration exhaled moisture, and other bodily secretions, it was also an efficient insulation, protecting the suit's wearer from evaporative chill The next two layers accomplished the separation of reusable water A complex system of fine tubes permeated the fabric They were equipped wife checkvalves at various points to keep the system's contents from reversing directions The tubes contained au at the beginning of the suit's cycle, die air pressure built up by the pumping action of the wearer's breathing and by heel pumps located on the soles of die suit At a pre-set pressure (which varied with the atmospheric conditions under which the suit was worn), the air was released into a holding chamber in the suit's hood This sudden release cooled the ait by the Joule-Thompson effect, and the cooled air was drawn back into the system and again run through jthe suit, dropping the temperature of the separating layers. The build-up release, return cycle would continue until the temperature dropped sufficiently to liquify ammonia produced when the suit's thigh-pads filtered the wearer's unne Once the ammonia had been uquified, the air was automatically retained in the hood chamber and the ammonia was pumped into the tubing system, keeping the temperature down until it was converted back to a gas by acquired heat, at which point the air cycle was triggered again Passing through this chilled area returned the trapped water vapor protected from ammonia contamination by the airtight nature of the tubing system, to liquid form This water was forced through the separating layers by both pumping pressure and osmosis and was subsequently trapped in the fourth layer Here another tubing system routed the re claimed water (from which salt precipitators, also located m the second and third layers, had removed most of the salinity) to the suit's catchpocfcet Any radiated body heat which survived the passage through the separating layers then passed through the fifth, outermost layer along with unreclaimed gases The stillsuit was considered an unattractive but essential garment bj most non-Fremen, its manufacture brought a stead) income to a number of sietch factories On Arrakis any man who valued his life would not venture into the desert without a stillsuit of Fremen manufacture, well maintained its importance can be seen not only in the survival of the Fremen themselves but in the death rate among Harkonnen servitors, to whom the tribes adamantly refused to sell their wares After Paul Muad'Dib Atreides became emperor, an interesting phenomenon took place Recognizing that the true source of the emperor's power lay in his Fremen, and wishing to advance themselves at Court, some sycophants adopted a custom of wearing stillsuits beneath their courtier's clothing That these individuals had taken to wearing the garments where they were not needed amused the emperor and his Fedaykm tremendously When it was discovered that all of the fashionable sttllsuits were non-functional replicas, their wearers were made the objects of such dension that they abandoned the practice The fashion was revived however, during the rule of Leto II the stillsuits worn by his museum Fremen were also useless The iro ny did not escape the God Emperor, and a number of his Journal entries refer to the Museum Fremen as "sand dandies, at whose dress a true Fremen would laugh unul no laughter remained Leto kept a small number of stillsuits, manufactured in the old style, at his Citadel, for use by persons he wished to accompany him into the Sareer CW 482 Further references; FREMBN STILL-TENT; Janet Oslo Fremen Lives and Legends (Saltlsa Secundus Morgan andShatak) SULLTETfF.