198 NOVUM ORGAN UM. 



50. In the twenty-sixth rank of prerogative instances we 

 will place the generally useful instances. They are such as 

 relate to various points, and frequently occur, sparing by 

 that means considerable labour and new trials. The proper 

 place for treating of instruments and contrivances will be 

 that in which we speak of the application to practice, and 

 the methods of experiment. All that has hitherto been 

 ascertained, and made use of, will be described in the par 

 ticular history of each art. At present we will subjoin a 

 few general examples of the instances in question. 



Man acts, then, upon natural bodies (besides merely 

 bringing them together or removing them) by seven prin 

 cipal methods: 1. By the exclusion of all that impedes 

 and disturbs ; 2. By compression, extension, agitation, and 

 the like ; 3. By heat and cold ; 4. By detention in a suitable 

 place ; 5. By checking or directing motion ; 6. By pecu 

 liar harmonies ; 7. 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 ves 

 sels 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 

 sapientia as the chymists 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 uninj ured 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 sub 

 stances capable of being poured round others. Grottos 

 and subterraneous caves are of great use in keeping off the 

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

 in the north of Germany are used for granaries. The de 

 positing of bodies at the bottom of water may be also men 

 tioned here, and I remember having heard of some bottles 



