مسائل المنتخبه (Articles Of Islamic Acts) - الخوئي، السيد أبوالقاسم - الصفحة ٣٧ - PURIFYING THINGS

and become sure that the original impurity has been removed.
١٨٠. If the ground which absorbs water (e.g. land on the surface of which there is fine sand) becomes impure it can be purified with under-Kurr water.
١٨١. If the floor which is made of stones or bricks or other hard ground in which water is not absorbed, becomes impure, can be purified with under-Kurr water.However, it is necessary that so much water is thrown on it that it begins to flow.
١٨٢. If the exterior of salt-stone or something resembling it becomes impure, it can be purified with under-Kurr water.
١٨٣. If sugar-loaf is made out of impure melted sugar and it is placed in Kurr or running water, it does not become pure.

II. EARTH
١٨٤. The earth purifies the sole of ones foot or shoe, provided that the following three conditions are fulfilled: (i) The earth should be pure (ii) The earthshould be dry (iii) If an original impurity, like blood or urine, or something which has become impure, like impure clay, is stuck on the sole of the foot or shoe of aperson, it should be cleared by walking on earth or by rubbing the foot or shoe on it. Furthermore, it is necessary that the earth consists of clay, or floor made of stonesor bricks, or any other similar thing. In case, however, the sole of ones foot or shoe is impure, it does not become pure by walking on a carpet or a mat or on green grass.
١٨٥. Purification of impure lower part of ones foot or shoe is also difficult as a consequence of walking on tar or wooden floor.
١٨٦. In order to purify the sole of ones foot or shoe it is better that one should cover a distance of at least fifteen cubits by walking on earth, even though theimpurity present there is already cleared by covering a lesser distance, or by rubbing ones foot on earth.