水是自然界中最好的一种溶剂。所以,我们从来不能在天然界中遇到纯净的水。纵然是雨水,它也会在其中溶解—些空气中的氧气、氮气及二氧化碳气等。倘再流经地面或地层,则其中所溶解的矿物质自属更多。如果所溶的矿物质的总重量在水中所占的比率,系小于百万分之一百(简写为100ppm,ppm表示parts permillion),则在化学上便将它称为软水;如果大于百万分之一百,则便将它称为硬水。硬水的缺点很多,主要的是在洗 Water is the best solvent in nature. Therefore, we can never encounter pure water in the natural world. Even if it is rain, it will dissolve in it - some of the oxygen, nitrogen and carbon dioxide in the air. If they flow through the ground or the ground, the dissolved minerals are more of their own. If the total weight of dissolved minerals in water is less than 100 parts per million (abbreviated as 100 ppm, ppm represents parts permillion), it is chemically called soft water; if it is greater than 1 million One hundred points, then it will be called hard water. The disadvantages of hard water are many, the main one is washing