SUBJECTS calces

In these treatises Boyle subjects many metals, calxes of... 

In 1775, Lavoisier published his paper on the composition of the air. In this historically interesting memoir, Lavoisier refers first to the action of heat upon a mixture of iron calx (oxide) and charcoal in giving fixed air, and to the similar action of mercury precipitate and charcoal. He then describes an experiment, in which he subjected the mercury precipitate to strong heat by itself and collected the expelled gas over water. This gas on examination gave properties familiar to us as those of oxygen. 

However different this opinion may seem to be from that of M. Stahl, it yet perhaps is not incompatible with it. It is possible that the addition of charcoal in the reduction of metals may answer two purposes at once 1st, That of restoring to the metal the inflammable principle which it has lost 2dly, That of restoring to the fixable elastic fluid in the metallic calx, the principle which constitutes its elasticity. But I repeat again that it is with great caution, that an opinion on so delicate, so difficult a subject should be hazarded a subject which is very nearly connected with one still more obscure, I mean the nature of elements themselves, or at least of what we regard as elements. Time and experiment alone can settle our opinions on these points. ... 

Trenes — Mercury is the Subject and Matter of the Stone. When you have amalgamated with it the calx of the perfected body, press it through a linen cloth, and again through a hare s bladder. If it passes clean through, then all is well. 

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