The Compendium of Caraka 3.7.22

3.7.22

Then, taking horse dung, spreading it on a large mat, drying it in the sun, pounding it in a mortar, and making it into a fine powder again on a grindstone, saturating it thoroughly eight or ten times in the sun with a decoction of viḍaṅga or a decoction of triphalā, reducing it again to a fine powder on a grindstone, and putting it in a new jar, he should keep it carefully stored.