88 Theory of the Bellows. 



velocity, and the water has had time to attain that velocity ; then the 

 surface of separation will be of the form opq. 



The explanation of the case of the turpentine, oil, and alcohol, is 

 obvious. Spirits of turpentine have more adhesiveness than alcohol, 

 and will consequently become soonest possessed of the velocity of 

 the apparatus, while it has less adhesiveness than oil, and the latter 

 will rise up round the jar even more rapidly than the upper surface 

 of the former. 



By adjusting balls of wax or other solids, exactly to the specific 

 gravity of each liquid, it is easy to observe the actual, as well as the 

 relative velocity of each, and particularly to determine which con- 

 tinues longest in motion after the jar has been brought to rest. M. 

 Thayer has varied his experiments by using a rectangular instead of 

 a cylindrical vessel ; but all such variations can only serve to com- 

 plicate the effect, without adding any thing to our knowledge of the 

 cause. In all this there is nothing new either in chemistry or hy- 

 drostatics. 



The most direct use which seems likely to be made of this expe- 

 riment, is to detect differences of adhesiveness between different li- 

 quids and solids, for which it may furnish a very delicate lest, 

 wherever the liquids in question allow of being placed one upon the 

 other. It may thus possibly connect itself with the important ques- 

 tion of the advantage of different unguents in obviating friction. 



Art. VI. — Theory of the Bellows ; by H. Strait. 



TO THE EDITOH. 



Dear Sir, — I here send you a communication on the true theory 

 and practice of constructing, moving and using bellows ; or, of ex- 

 haustion and compression or condensation of air on the principle of 

 a balance, which I have lately discovered, and which promises, in 

 my estimation, to be a valuable and powerful acquisition to practical 

 blowing, desiring you to give it an immediate publication, as I am 

 now engaged in giving it a thorough experimental demonstration. 1 

 will now proceed to illustrate the principles of my theory of exhaus- 

 tion and compression of air, by representation and description, first, 

 of compression, then exhaustion, and conclude with some general re- 

 marks on its advantages, he. 



