17. Green and moist vegetable matter confined and rubbed together, as roses, peas in baskets; so hay, if it be damp when stacked, often catches fire. 18. Quicklime sprinkled with water. 19. Iron, when first dissolved by acids in a glass, and without any application to fire; the same of tin, but not so intensely. 20. Animals, particularly internally; although the heat is not perceivable by the touch in insects, on account of their small size. 21. Horse dung, and the like excrement from other animals, when fresh. 22. Strong oil of sulphur and of vitriol exhibit the operation of heat in burning linen. 23. As does the oil of marjoram, and like substances, in burning the bony substance of the teeth. 24. Strong and well rectified spirits of wine exhibit the same effects; so that white of eggs when thrown into it grows hard and white, almost in the same manner as when boiled, and bread becomes burned and brown as if toasted. 25. Aromatic substances and warm plants, as the dracunculus [arum], old nasturtium, etc., which, though they be not warm to the touch (whether whole or pulverized), yet are discovered by the tongue and palate to be warm and almost burning when slightly masticated. 26. Strong vinegar and all acids, on any part of the body not clothed with the epidermis, as the eye, tongue, or any wounded part, or where the skin is removed, excite a pain differing but little from that produced by heat. 27. Even a severe and intense cold produces a sensation of burning.[83] “Nec Boreæ penetrabile frigus adurit.” 28. Other instances. We are wont to call this a table of existence and presence. XII. We must next present to the understanding instances which do not admit of the given nature, for form (as we have observed) ought no less to be absent where the given nature is absent, than to be present where it is present. If, however, we were to examine every instance, our labor would be infinite. Negatives, therefore, must be classed under the affirmatives, and the want of the given nature must be inquired into more particularly in objects which have a very close connection with those others in which it is present and manifest. And this we are wont to term a table of deviation or of absence in proximity. _Proximate Instances wanting the Nature of Heat_ The rays of the moon, stars, and comets, are not found to be warm to the touch, nay, the severest cold has been observed to take place at the full of the moon. Yet the larger fixed stars are supposed to increase and render more intense the heat of the sun, as he approaches them, when the sun is in the sign of the Lion, for instance, and in the dog-days.[84]