282 Transhttion of Key's Essays. 



sides, by moisture cannot be understood a naked quality, but 

 ratber water or air invested with it. As to water, whence could 

 the calx derive it, none being near it ? Is there any air more 

 humid than usual in the laboratory in which the calcination is 

 carried on? Will not the heat of the furnace have absorbed it ? 

 And if the calx should attract so much water, or cloudy air, 

 as to increase its weight, a fifth part or thereabouts, as by the 

 experiment, we should have a mortar rather than a dry calx. I 

 add, besides, that at the instant of calcination the calx will be 

 found increased before it can have had time to affect this ima- 

 ginary attraction. 



ESSAY XXV. 



Bi/ one siwjle experiment, all the opinions opposed to mine are 

 wholly destroyed. 

 It is said of Hercules, that he had no sooner cut off one head 

 of the hydra that ravaged the Lernean viarsh, than two sprung 

 forth — my state is like his. The error I combat abounds in 

 opinions, which are so many heads ; if I cut off one, two start 

 up: my labour is always increasing, and I believe I shall never 

 have done, if I employ myself in chopping them off" one after 

 another. I must collect my strength, and stiffen my arm, to 

 sever them all at one blow, and lay the monster low in death. 

 Let him beware, whom it concerns, for here I deal the deadly 

 stroke. I have read in Hamerus Poppius, in the third chapter 

 of his book, entitled " Basilica Antimonii," his new method of 

 calcining antimony. He takes a certain quantity of it, weighs 

 it, and, having reduced it to powder, places it in a conical form 

 on a marble slab ; then, placing a burning-glass in the sun's 

 rays, he directs their focus on the apex of the cone of antimony, 

 which then fumes abundantly, and in a short time the part on 

 which the rays full is converted into a very white calx, which he 

 separates with a knife, and directs the rays on the remainder, 

 till the whole becomes white, when the calcination is complete. 

 It is a wonderful thing (he adds afterwards), that although in 

 this calcination the antimony loses much of its substance, by 

 the vapours and fumes which exhale copiously, yet, so it is, its 



