مسائل المنتخبه (Articles Of Islamic Acts) - الخوئي، السيد أبوالقاسم - الصفحة ٤٤ - PURIFYING THINGS

IX. REMOVAL OF ORIGINAL IMPURITY
٢٢٢. If the body of an animal is stained with an original impurity like blood or with something which has become impure, for example impure water, its body becomespure after the removal of the impurity. Similarly the inner parts of the human body, for example, mouth or nose, become pure after the removal of impurity from there. Hence,if blood comes out of the gums of a person and loses all its traces in saliva, rinsing the mouth is not necessary. However, if artificial teeth become impure within the mouththey should be purified with water.
٢٢٣. If some particles of food remain between ones teeth and then blood comes out within his mouth and he is not aware whether blood has touched those particles offood they are pure and if blood touches them they become impure.
٢٢٤. If those parts of the lips and eyelashes, which join each other when the lips or eyes are closed, and those parts of the body, about which it is not known asto whether they should be treated to be external parts or internal ones, become impure, they should be washed with water.
٢٢٥. If impure dust settles on a cloth or carpet but is shaken off and thereafter something wet touches that cloth etc. that thing will not become impure.

X. CONFINING (ISTABRA) OF AN ANIMAL WHICH EATS IMPURITIES
٢٢٦. The dung and urine of an animal, which gets habituated to eating faeces, is impure, and it could be purified by subjecting it to "istabra" i.e. it should beprevented from eating impurities and pure fodder should be given to it till such time that it may not be called an animal which eats impurities. On the basis of obligatoryprecaution the following animals should be prevented from eating impurities for the period specified: Camel for ٤٠ days. Cow for ٢٠ days. Goat/Sheep for