1819.] Royal Danish Society. 01 



possibility ofwaterthatitis not to be doubted of, yet the degree in 

 which water can be compressed by a certain force and the law ac- 

 cording to which the compression takes place are subject to uncer- 

 tainties, and even very considerable ones. Some mathematicians 

 and philosophers indeed were of opinion that the said compressi- 

 bility of water was proportioned to the force employed ; but the 

 experiments of Abich and Zimmermann, which are the only series 

 of experiments of the compressibility of water by unequal powers, 

 seemed to be entirely contradictory to this opinion, wherefore 

 Gehler, in the account which he has given in his dictionary of 

 the experiments on the compressibility of water, plainly tells us 

 that it has not been possible to discover any law in the quantities 

 that occurs thereby. The same judgment has been passed by 

 all other philosophers on the results of the experiments of Abich 

 and Zimmermann. 



Prof. (Ersted undertook to examine them anew, and was sur- 

 prised at finding that the calculations of the results of the expe- 

 riments, although of the easiest kind in Zimmermann's book, 

 were perplexed by mistakes of consequence. By correcting them 

 it appeared that the experiments described did not prove that 

 unboiled water is less compressible than boiled, but that, on the 

 contrary, as might be expected, it was even more compressible. 

 It was likewise demonstrated that the compressions, so far ass 

 the experiments were not undertaken with the greatest power, 

 which, perhaps, might compress the piston itself, were propor- 

 tioned to the compressing powers. This induced the author to 

 get a machine made for the compression of water. It consisted 

 of a very wide and thick brass cylinder, and a thin tube with a 

 piston for the compression of the water. By means of thin 

 machine, the water was compressed by applying but very little 

 force, and very small alterations in the place rilled with the water 

 were measured. In order to measure or compute the compress- 

 ing power, which cannot be done immediately with sufficient 

 exactness on account of the friction of the piston, an appendage 

 was made to the wide cylinder into which a narrow and strong 

 glass tube was screwed. This was filled with air, which by the 

 greatness of its compressibility showed, after the lawofMariotte, 

 the quantity of the pressing power. By this instrument he 

 found that the compression of the water was proportional to that 

 of the air, consequently in proportion with the compressing powers. 

 At 12° of the centigrade thermometer this compression differs 

 very little from 0-00012 for a pressure equal to that of the atmo- 

 sphere. He has likewise extended his criticisms to Canton's expe- 

 riments, and has shown that a just estimation of the influx of heat 

 into the water would give a greater compressibility than that 

 which the English philosopher has concluded. As De La 

 Place has founded his calculations of the swiftness of the sound 

 in water upon the experiments of Canton, the result of his calcu- 

 lation must be adjusted after the later experiments. 



