224 



Prof. Oersted on the Law qfthe 



discover a sensible quantity of it. It may also be a consti- 

 tuent part of some meteorolites, which in many respects have a 

 resemblance to the products of the floetz trap formation; but 

 I have now no opportunity to verify this hypothesis. 



I am, 



Dear Sir, 



With high esteem, yours, Stc. 

 C. G. Gmelin. 

 Tubingen, 31st Dec. 1825. 



Art. VIII. — On the Law of the Compression of Air, and of 

 Gases capable of being Liquefied by Pressure. By H. C. 

 Oersted, Professor of Natural Philosophy in the Univer- 

 sity of Copenhagen. Communicated by the Author. 



The law of Mariotte,* according to which the volumes of a 

 mass of air are reciprocal to the pressures which they suffer, 

 has not yet been established by accurate experiments, unless 

 in the case of very weak pressures. With regard to high 

 pressures, it may still be doubted whether or not they 

 follow the same ratio. Several distinguished philosophers 

 have taken for granted the accuracy of this law, for all the 

 pressures to which a mass of air can be subjected, while others, 

 such as James Bernouilli and Euler, suppose that the volumes 

 decrease in a much less progression ; whereas, in the small 

 number of experiments that have been made under consider- 

 able pressures, the volumes decrease in a much higher pro- 

 gression than the pressure. This result, indeed, has been ob- 

 tained by Sulzer-J- and by Dr Robison, as will appear from 

 the following tables : 



• This law was first deduced from the experiments of the celebrated 

 Boyle, by his friend Richard Townley, but as it is so well known under the 

 name of Mariotte, who discovered it nearly at the same time, and by his 

 own experiments, I have made use of this name, already consecrated by 

 time. 



t See the Memoirs of the Academy of Berlin. 



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