Translation of Rey's Essays. 57 



in this matter. Homogeneous bodies, they say, are those 

 whose parts are all of the same nature, or which have the 

 same name and definition as the whole. I certainly agree that 

 fire acting on such bodies, does, of its own accord and nature, 

 {de soy et par sa nature, J dilate them f but reason teaches 

 me, and experience confirms it, that, by accident, as we say, and 

 in consequence of the subtilization and separation of some 

 parts, the others remain thick and heavy. If that be denied 

 me, and the aforesaid doctrine must be rigorously investigated, 

 as if fire, neither by itself nor by accident, could thicken homo- 

 geneous bodies, I challenge it as false, and could bring forward 

 a cloud of instances to the encounter; but the courteous reader, 

 for whom I labour, will be contented with a few. 



Vitriol is a homogeneous body, for its parts have the same 

 name and definition as the whole. Now, if this be put in a 

 retort, fire so acts upon it, that it shews us separately its 

 phlegm, its oil, and its colcothar, parts which differ in thick- 

 ness and weight. Turpentine is a homogeneous body, the 

 smallest part being no less turpentine than the whole mass ; if 

 this be put in an alembic, fire, by its action, dilates some of 

 its parts, and thickens others, separating its water, spirit, oil 

 and colophony, whose difference in respect of weight and 

 subtlety is notorious. I have already spoken of wine, (also a 

 homogeneous body,) which fire, displaying its powers on it in 

 distillation, extends and dilates till it extracts its brandy 

 and weak water (eau petite,) as it is called ; and the residuum 

 is thicker in proportion to the quantity of this water or phlegm 

 that has been drawn off. But why do I take the trouble to bring 

 forward these examples, since it is evident, that from all such 

 bodies, salt, sulphur, and mercury, parts which sensibly differ 

 in tenuity and weight are extracted by the help of fire ; it is 

 not true, therefore, that fire dilates all their parts equally. I 

 well foresee that some will endeavour to evade this, by saying 

 that the instances I propose are of compound bodies, and 

 that it would be otherwise with those that are simple. Yet, 

 forsooth, have I pxovcd the falsity of this maxim, taken, as 

 they lay it down, ia its general sense, and extended to uU ho- 



