43 o BACON 



as possible, and until the sides of the bladder met. We first, 

 however, rubbed the bladder gently with oil, so as to make it 

 air-tight' by closing its pores with the oil. We tied the bladder 

 tightly round the mouth of the vial, which we had inserted in 

 it, and with a piece of waxed thread to make it fit better and 

 more tightly, and then placed the vial on some hot coals in a 

 brazier. The vapor or steam of the spirit, dilated and become 

 aeriform by the heat, gradually swelled out the bladder, and 

 stretched it in every direction like a sail. As soon as that was 

 accomplished, we removed the vial from the fire and placed 

 it on a carpet, that it might not be cracked by the cold ; we 

 also pricked the bladder immediately, that the steam might not 

 return to a liquid state by the cessation of heat, and confound 

 the proportions. We then removed the bladder, and again 

 took the weight of the spirit which remained; and so calcu- 

 lated the quantity which had been converted into vapor, or an 

 aeriform shape, and then examined how much space had been 

 occupied by the body in its form of spirits of wine in the vial, 

 and how much, on the other hand, had been occupied by it in 

 its aeriform shape in the bladder, and subtracted the results; 

 from which it was clear, that the body, thus converted and 

 changed, acquired an expansion of one hundred times beyond 

 its former bulk. 



Again, let the required nature be heat or cold, of such a de- 

 gree as not to be sensible from its weakness. They are ren- 

 dered sensible by the thermometer, as we described it above ; 

 for the cold and heat are not actually perceived by the touch, 

 but heat expands and cold contracts the air. Nor, again, is 

 that expansion or contraction of the air in itself visible, but 

 the air when expanded depresses the water, and when con- 

 tracted 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 whey 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, irf 

 this branch men have labored hard in distillations and artificial 

 separations, but with little more success than in their other ex- 

 periments 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 destruc- 

 tion of any delicate conformation, in which principally consist 

 the hidden virtues and sympathies. Nor do men in these sepa- 



