Niddah

Amemar also citing Raba ruled: A woman  must wash her head in warm water only and she may do it even with such as was warmed by the sun  but not with cold water. Why not with cold water? — Because cold water  loosens  the hair. Raba further ruled: A man should always give instructions to his household that a woman  should wash the folds of her body  with water. An objection was raised: It is not necessary for the water  to penetrate into the folds of the body  or to its concealed parts!  — Granted that it is not necessary for the water to penetrate,  it is necessary nevertheless that it be capable of penetration to every part;  in agreement with a ruling of R. Zera. For R. Zera ruled: Wherever proper mingling  is possible actual mingling is not essential,  but where proper mingling is not possible  the actual mingling is indispensable. Rabin son of R. Adda citing R. Isaac stated: It once happened that a bondmaid of Rabbi performed immersion and when she ascended [from the water] a bone constituting an interposition was found between her teeth, and  Rabbi required her to perform a second immersion. Raba further ruled: If a woman performed immersion, and when she ascended [from the water] an object that caused an interposition was found upon her, she need not wash her head or perform immersion again if her immersion was performed immediately after the washing of her head;  otherwise, she must wash her head and perform immersion again. There are others who say: If she performed her immersion on the same day on which she washed her head, she need not wash her head or perform immersion again, otherwise she must wash her head and perform immersion again. What is the practical difference between them?  — The practical difference between them is the question whether immersion must follow immediately upon the washing of the head,  and whether a woman may wash her head during the day and perform her immersion at night. Raba ruled: A woman may not stand upon an earthenware when she is to perform ritual immersion. R. Kahana intended to say, 'What is the reason? Because a preventive measure has been enacted against the possibility of using  bath-houses,  but that it is quite proper to stand upon a block of wood'. Said R. Hanan of Nehardea to him, 'What is the reason  there?  Because she is frightened;  on a chip of wood she is also frightened'. R. Samuel b. R. Isaac ruled: A woman shall not perform immersion