NOVUM ORGANUM 379 



Every ignited body that is red-hot is always warm, although 

 without flame, nor is any negative instance subjoined to this 

 affirmative. Rotten wood, however, approaches nearly to it, for 

 it shines at night, and yet is not found to be warm; and the 

 putrefying scales of fish which shine in the same manner are 

 not warm to the touch, nor the body of the glowworm, or of the 

 fly called Lucciola. 



The situation and nature of the soil of natural warm baths 

 have not been sufficiently investigated, and therefore a negative 

 instance is not subjoined. 



To the instances of warm liquids we may subjoin the negative 

 one of the peculiar nature of liquids in general ; for no tangible 

 liquid is known that is at once warm in its nature and constantly 

 continues warm ; but their heat is only superinduced as an ad- 

 ventitious nature for a limited time, so that those which are 

 extremely warm in their power and effect, as spirits of wine, 

 chemical aromatic oils, the oils of vitriol and sulphur, and the 

 like, and which speedily burn, are yet cold at first to the touch, 

 and the water of natural baths, poured into any vessel and sepa- 

 rated from its source, cools clown like water heated by the fire. 

 It is, however, true that oily substances are rather less cold to 

 the touch than those that are aqueous, oil for instance than water, 

 silk than linen ; but this belongs to the table of degrees of cold. 



In like manner we may subjoin a negative instance to that of 

 warm vapor, derived from the nature of vapor itself, as far as we 

 arc acquainted with it. For exhalations from oily substances, 

 though easily inflammable, are yet never warm unless recently 

 exhaled from some warm substance. 



The same may be said of the instance of air; for we never 

 perceive that air is warm unless confined or pressed, or mani- 

 festly heated by the sun, by fire, or some other warm body. 



A negative instance in exhibited in weather by its coldness 

 with an east or north wind, beyond what the season would lead 

 us to expect, just as the contrary takes place with the south or 

 west winds. An inclination to rain (especially in winter) at- 

 tends warm weather, and to frost cold weather. 



A negative instance as to air confined in caverns may be ob- 

 served in summer. Indeed, we should make a more diligent 

 inquiry into the nature of confined air. For in the first place 

 the qualities of air in its own nature with regard to heat and 

 cold may reasonably be the subject of doubt ; for air evidently 

 derives its heat from the effects of celestial bodies, and possibly 

 its cold from the exhalation of the earth, and in the mid region 

 of air (as it is termed) from cold vapors and snow, so that no 

 judgment can be formed of the nature of air by that which is out 

 of doors and exposed, but a more correct one might be derived 

 from confined air. It is necessary, however, that the air should 



