3: Conspicuous Instance or Coruscations

3. Conspicuous instance or coruscations, or free and predominant instances

²⁴ This is of which we spoke in our first vintage of the form of heat.

These show the required nature in its bare substantial shape.

At its greatest power, emancipated and free from all impediments, or at least overcoming, suppressing, and restraining them by the strength of its qualities;

Every body is susceptible of many united forms of natures in the concrete, the consequence is that they mutually deaden, depress, break, and confine each other, and the individual forms are obscured.

But there are some subjects in which the required nature exists in its full vigor rather than in others, either from the absence of any impediment, or the predominance of its quality. Such instances are eminently conspicuous.

But even in these care must be taken, and the hastiness of the understanding checked, for whatever makes a show of the form, and forces it forward, is to be suspected, and recourse must be had to severe and diligent exclusion.

For example, let heat be the required nature.

The thermometer is a conspicuous instance of the expansive motion, which (as has been observed) constitutes the chief part of the form of heat;

Flame exhibits expansion. Yet its being extinguished every moment stops this progress of expansion.

Boiling water [165] converts into vapor. But it does not so well exhibit the expansion of water in its own shape.

Red-hot iron and the like are so far from showing this progress, that, on the contrary, the expansion itself is scarcely evident to the senses, on account of its spirit being repressed and weakened by the compact and coarse particles which subdue and restrain it. But the thermometer strikingly exhibits the expansion of the air as being evident and progressive, durable and not transitory.[111]

Take another example. Let the required nature be weight. Quicksilver is a conspicuous instance of weight; for it is far heavier than any other substance except gold, which is not much heavier, and it is a better instance than gold for the purpose of indicating the form of weight; for gold is solid and consistent, which qualities must be referred to density, but quicksilver is liquid and teeming with spirit, yet much heavier than the diamond and other substances considered to be most solid; whence it is shown that the form of gravity or weight predominates only in the quantity of matter, and not in the close fitting of it.[112]