Neither can the loss of this heat render them heavy, for I have already proved that nothing increases in weight but by the addition of matter, or by … - Jean Rey

With regard to the celestial heat making bodies light, Scaliger very properly objects that the heavens, which abound in this heat, as being the source of it, must be light (feut leger) and consequently univocal (univoque) with the other bodies, which is absurd.

The chemists furnish us with a pretty representation of this, by taking pulverized black enamel, liquor of tartar, brandy tinged blue with litmus, and spirit of turpentine reddened by alkanet, and shaking the whole together in a phial, till it forms one confused mixture. The vessel being then left at rest, it is pleasant to see the clearing off of the confusion. The enamel gains the lowest station, representing earth; the liquor of tartar settles close by it, representing water; the brandy, like the air, occupies the third place; and spirit of turpentine, to shew the nature of fire, arranges itself above them all. All this is effected by the influence of weight, according as it is largely or sparingly distributed amongst these bodies. In the same manner the elements acknowledge no other cause that arranges and disposes each in its proper place, it being needless to introduce levity, which our predecessors vainly devised for that purpose.

I have now made the preparation; laid as it were the foundations of my answer to the Sieur Burn's [or Brun's] demand; namely, that having put two pounds six ounces of fine English tin into an iron vessel, and heated it strongly on an open fire for six hours, stirring it continually, without having added anything, he obtained two pounds thirteen ounces of a white ; which at first occasioned him great surprise, and the desire to ascertain whence these seven ounces of increase were derived.