284 Translation of Key's Essays. 



heavy by the sun's rays, mixes with the calx in proportion as 

 the antimony is attenuated by the calcination, and adheres to 

 its minutest parts. This fact fully establishes the truth of my 

 opinion as to the increased weight of the lead and tin, which 

 can have no other cause than the mixture of the thickened air — 

 there being no difference between their increase and that of the 

 antimony, except that in the latter case the air is thickened by 

 the solar rays, and in the former by the heat of common fire. 



Essay XXVI. 

 Why the calx does not increase in iveight ad infinitum. 



Having thus confuted the opposite opinions, my own alone 

 ean freely keep the field. It is true, that perceiving some ob- 

 jections which might disturb its progress, I step forward to set 

 them aside. The first would seem to lead to the absurdity I 

 have objected to Caesalpin, that, admitting my opinion, the calx 

 will increase ad infinitum. For why it will be said, will not 

 the calx increase infinitely, since the fire may be infinitely con- 

 tinued, which will always supply that thickened and heavy air 

 which causes its increase ? I rid myself of this difficulty, 

 which might insnare one of the less subtle sort, by observing, 

 that all matter which increases by the addition of another is 

 either solid or liquid, and that the mixture takes place be- 

 tween them in three ways. Either the solid matter mixes with 

 solid, or the liquid with liquid, or one of them with the other. 

 The mixture and increase which is effected in the two first ways 

 has no bounds. You may mix sand with sand for ever, the in- 

 crease will have no end. So you may mix wine with wine, and 

 never have done — but it is not so with the third method, when 

 we add and mix together a liquid with a solid : such mixed 

 addition will not increase for ever, will not go on to infinity. 

 Nature, in her inscrutable wisdom, has here placed bounds 

 which she never oversteps — mix water with saud or flour, their 

 smallest parts wHl be enveloped by it ; pour a fresh quantity on, 

 and they will not take up any more ; and if we withdraw them 

 from the water, they will only carry oflF what adheres to them, 

 and is sufficient exactly to encompass them. Immerse them 



