Translation of Key's Easai/s. 285 



ngain n hnndrod and a hundred times, they will not come out 

 more loaded with it, and if left at rest in the water, they quit 

 the superfluous quantity, and sink of their own accord to tlie 

 bottom : so religiously does nature stop at the limits she has 

 once prescribed to herself. Our calx is in this predicament ; 

 the thickened air attaches itself to it, and goes on adhering by 

 degrees to its most minute particles : thus its weight increases 

 from the beginning to the end ; but when the whole is clothed 

 with it, it can take no more. Do not continue your calcina- 

 tion with that hope ; you will lose your pains. As for the rest, 

 let not what was said in the eleventh chapter disturb you, where 

 I used the expression, " this air, no longer air, but rather an air 

 deprived of its nature," for these are words in excess, by which 

 I mean only, that this air has been deprived of that liquid 

 subtlety, which prevented its adhering to any thing, and is 

 rendered more gross, heavy, and adhesive. 



Essay XXVII. 



Whj all other calces and ashes do not increase in weight. 



I proceed to another objection that may be started. Why do 

 not all other calces and ashes, formed by the force of fire, in- 

 crease in weight as well as the calx of tin or lead ? What pri- 

 vilege have these more than the rest } I answer, that those 

 things which are calcinable, or convertible into ashes, are of 

 different natures. Some have a great deal of exhalable and 

 evaporable matter; or (speaking like the alchymists) much sul- 

 phur and mercury, which the fire continually drives off to the 

 end. Hence, much loss, few ashes, which cannot attach to 

 themselves so much of the thickened air, as even to supply the 

 loss. Others have little exhalable or evaporable matter, or in 

 other words, little sulphur and mercury; hence small loss, 

 much ashes (for the abundance of salt) which attracts so much 

 of the thickened air, that not only the loss is supplied, but be- 

 sides the weight increases largely beyond it. Stones, ve- 

 getables, and animals commonly arc of the first order; lead and 

 tin, of the second. There arc other things whose volume is so 

 much extended by calcination, that even if little or no matter 



Vol. XIII. X 



