BOOK II.] HERMETICAL CLOSINQ 666' 



to make the exclusion more perfect, and to remove tlic air and 

 celestial influence. We have sometimes made an experiment by 

 placing a vessel or other bodies in quicksilver, the most dense of 

 all substances capable of beino^ poured round others. Grottos 

 and subterraneous caves are of great use in keeping off the 

 effects ot the sun, and the predatory action of air, and in the 

 north of Germany are used for granaries. The depositing of 

 bodies at the bottom of water may be also mentioned here ; and 

 I remember having heard of some bottles of wine being let down 

 into a deep well in order to cool them, but left there by chance,' 

 carelessness, and i'orgetfulness for several years, and then taken 

 out ; by which means the wine not only escaped becoming flat 

 or dead, but was much more excellent in flavour, arising (as it 

 appears) from a more complete mixture ot its parts. But if the 

 case require that bodies should be sunk to the bottom of water, 

 as in rivers or the sea, and yet should not touch the water, nor 

 be inclosed in sealed vessels, but surrounded only by air, it 

 would be right to use that vessel which has been sometimes 

 employed under water above ships that have sunk, in order to 

 enable the divers to remain below and breathe occasionally by 

 turns. It was of the following nature : — A hollow tub of metal 

 was formed, and sunk so as to have its bottom parallel with the 

 surface of the water ; it thus carried down with it to the bottom 

 of the sea all the air contained in the tub. It stood upon three 

 feet (like a tripod), being of rather less height than a man, so 

 that, when the diver was in want of breath, he could put his 

 head into the hollow of the tub, breathe, and then continue his 

 work. We hear that some sort of boat or vessel has now been 

 invented, capable of carrying men some distance under water. 

 Any bodies, however, can easily be suspended under some such 

 vessel as we have mentioned, which has occasioned our remarks 

 upon the experiment. 



Another advantage of the careful and hermetical closing of 

 bodies is this, — not only the admission of external air is pre- 

 vented (of which we have treated), but the spirit of bodies also 

 is prevented from making its escape, which is an internal opera- 

 tion. For any one operating on natural bodies must be certain 

 as to their quantity, and that nothing has evaporated or escaped, 

 since profound alterations take place in bodies, when art pre- 

 vents the loss or escape of any portion, whilst nature prevents 

 their annihilation. With regard to this circumstance, a false 

 idea has prevailed (which if true would make us despair of pre- 

 serving quantity without diminution), namely, that the spirit of 

 bodies, and air when rarefied by a great degree of heat, cannot 

 be so kept in by being inclosed in any veesel as not to escape by 

 the small pores. Men are led into this idea by the common 

 experiments of a cup inverted over water, with a candle or 



