222 NOVUM ORGANUH 



itself visible, but the air when expanded depresses the 

 water, and when contracted raises it, which is the first 

 reduction to sight. 



Again, let the required nature be the mixture of bodies; 

 namely, how much aqueous, oleaginous or spirituous, ashy 

 or salt parts they contain; or, as a particular example, how 

 much butter, cheese, and wliey there is in milk, and the 

 like. These things are rendered sensible by artificial and 

 skilful separations in tangible substances; and the nature 

 of the spirit in them, though not immediately perceptible, 

 is nevertheless discovered by the various motions and 

 efforts of bodies. And, indeed, in this branch men have 

 labored hard in distillations and artificial separations, but 

 with little more success than in their other experiments 

 now in use; their methods being mere guesses and blind 

 attempts, and more industrious than intelligent; and what 

 is worst of all, without any imitation or rivalry of nature, 

 but rather by violent heats and too energetic agents, to the 

 destruction of any delicate conformation, in which princi 

 pally consist the hidden virtues and sympathies. Nor do 

 men in these separations ever attend to or observe what we 

 have before pointed out; namely, that in attacking bodies 

 by fire, or other methods, many qualities are superinduced 

 by the fire itself, and the other bodies used to effect the 

 separation, which were not originally in the compound. 

 Hence arise most extraordinary fallacies; for the mass of 

 vapor which is emitted from water by fire, for instance, did 

 not exist as vapor or air in the water, but is chiefly created 

 by the expansion of the water by the heat of the fire. 



So, in general, all delicate experiments on natural or 

 artificial bodies, by which the genuine are distinguished 

 from the adulterated, and the better from the more com- 



