NOVUM ORGANUM 221 



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 blad 

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

 serted 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 pro 

 portions. We then removed the bladder, and again took 

 the weight of the spirit which remained; and so calculated 

 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 occu 

 pied by it in its aeriform shape in the bladder, and sub 

 tracted 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 degree as not to be sensible from its weakness. They are 

 rendered sensible by the thermometer, as we described it 

 above; 69 for the cold arid 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 



69 See Table of Degrees, No. 38. 



