Essays of Jean Rey, doctor of medicine, on an enquiry into the cause wherefore tin and lead increase in weight on calcination. (1630).

  • Jean Rey
Date:
1904
Catalogue details

Licence: In copyright

Credit: Essays of Jean Rey, doctor of medicine, on an enquiry into the cause wherefore tin and lead increase in weight on calcination. (1630). Source: Wellcome Collection.

Provider: This material has been provided by UCL Library Services. The original may be consulted at UCL (University College London)

    57/64 (page 53)
    namely, that I almost called that air no longer air but an unnatural air: for these are words of excess, by which I mean nothing more than that the air has been deprived of that liquid subtlety which caused it not to adhere to any substance, and has become gross, heavy, and adherent. ESSAY XXVII. Why all other calces and ashes do not increase in weight. I come to another objection which might be raised. Why do not all other calces and ashes made by the force of fire increase in weight as well as the calx of tin and of lead ? What privilege have these over the others ? I answer that the things calcined or incinerated are of dif- ferent nature. Some have much exhalable and evapor- able matter, or (speaking spagyrically) much sulphur and mercury, which the fire expels to the end. Here there is much diminution and little ash, which cannot attach to itself as much of the air condensed by fire as even to make up for the decrease. Others have little exhalable and evaporable matter, or little sulphur and mercury : •consequently there is little diminution, much ash (from the abundance of salt) which attracts so much of the condensed air, that not only is the diminution made good, but the weight increases largely in addition. Stones, vegetables, and animals are usually in the first named class. Lead and tin in the second. There are other things which calcination carries to such increase of volume, that even if little or no matter were lost, the weight would nevertheless be much diminished, not so much when examined by aid of the reason as when examined by the balance. Such are the Indian metal named Calaem,* and a species of crocus of iron, such as ■Chemists can exhibit. * [Zinc]