We have seen that a ketem causes a woman to be considered a nidda, and she is considered tameh. But how can one be certain that the stain is blood and not dye or paint? The Mishna on today’s daf discusses that question.
Seven substances must be applied to a stain: tasteless saliva, liquid from split beans, urine, natron, lye, Cimolian earth, and lion’s leaf. If one immersed the stained garment and, having handled ritually pure things with it, applied to it the seven substances and the stain did not fade away it must be a dye; and the pure things remain pure and there is no need to immerse it again. If the stain faded away or grew fainter, it must be a bloodstain and the pure things are impure and it is necessary to perform immersion again.
This list of cleansing agents teaches us that during the period of the Mishna there were a large number of substances that were used to clean. Some broke down the stain by means of enzymes, like saliva or beans. Others were minerals, like natron (sodium carbonate decahydride Na2CO3-10H2O) or Cimolian earth – קימוניא – a heavy clay found commonly in the Aegean. Some were plants that were ground up or burned and their remains were used to clean, like lye – potash – and lion’s leaf (Leonotis leonurus), a member of the mint family with mild psychoactive properties, could also be burned to produce potash.
When the Mishna mentions “tasteless saliva” it refers to concentrated saliva, i.e. spittle that is found in one’s mouth after a night of sleep, which has not been contaminated by food or drink. This saliva is rich in enzymes. These enzymes break up organic matter, which makes them effective as cleansing agents. The baraita teaches that there were other cleansing agents that could be used, as well. One of them is called ahal.
Several plants in Israel are called ahal. One of them – ahal ha-gevishim (Mesembryantnenum cristalimum L.) – is an annual plant that grows among rocks and on walls that face the sea. This plant contains large amounts of soda, and was used for bathing and washing clothing.