6 CLASSICS OF MODERN SCIENCE 



in a suitable place; V. by checking or directing motion; VI. by 

 peculiar harmonies; VII. by a seasonable and proper alternation, 

 series, and succession of all these, or, at least, of some of them. 

 I. With regard to the first — common air, which is always at hand, 

 and forces its admission, as also the rays of the heavenly bodies, 

 create much disturbance. Whatever, therefore, tends to exclude 

 them may well be considered as generally useful. The substance 

 and thickness of vessels in which bodies are placed when prepared 

 for operations may be referred to this head. So also may the accurate 

 methods of closing vessels by consolidation, or the lutum sapientice 

 as the chemists call it. The exclusion of air by means of liquids at 

 the extremity is also very useful, as when they pour oil on wine, or 

 the juices of herbs, which by spreading itself upon the top like a 

 cover, preserves them uninjured from the air. Powders, also, are 

 serviceable, for although they contain air mixed up in them, yet they 

 ward off the power of the mass of circumambient air, which is seen 

 in the preservation of grapes and other fruits in sand or flour. Wax, 

 honey, pitch, and other resinous bodies, are well used in order to 

 make the exclusion more perfect, and to remove the 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 being poured round others. Grottoes and subterraneous 

 caves are of great use in keeping ofif the effects of 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 forgetfulness, for several years, 

 and then taken out; by which means the wine not only escaped be- 

 coming flat or dead, but was much more excellent in flavor, arising 

 (as it appears) from a more complete mixture of 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 

 enclosed 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 



