Bern, Burgerbibliothek, Cod. 402

it burns the ends. For the same reason, the thickest of cooked things are the hottest, such as milk, and generally, thick broths [are hotter] than water, or if one puts something on the water, it heats up more quickly or more slowly; for instance, the barrier traps and prevents the heat from evaporating outward, just like things that are covered, and at the same time, as it has been heated, it stays hot. For everything possessing a certain density manages to do this because it retains [the heat]. In general, [heat] is spoken of in many ways: that which is in fine things and flows, and does not remain, and being small-particled, does not burn in the same way; that which is the opposite of this, because of its lack of evaporation, becomes both more [intense] and stronger and lasts longer. Of the flame, the center is the least bright, and the bottom and the extreme tip are red. Of the flame, the center is always the brightest and clearest, while the bottom and the extreme tip are red and more blackened. This appears most clearly in oil lamps, because this [part] is the least mixed with the vapor. For that which is near the wick itself, and the lamps, since the vapor is carried toward this, naturally blackens more. But at the tip, a kind of confluence occurs as it is already ending and at the same time taking up the part; for the strength and the movement of the flame are upward, that the strength and movement of the flame are upward and for this reason the smoke is carried in this direction most of all. Perhaps even that [theory] of ours is not ill-stated and is true: that it neither becomes what is not yet, nor is what is being destroyed the same [as the original]; it is formed from below, but it is destroyed from above by the air. The middle part is, as it were, clean and pure. For this reason, one cannot see through this part, while the upper parts obscure [it] because they converge into a point and because of the motion. A puzzle is raised: why the flame about the shape of fire