3^52 On the Compressihility of Water. 



The experiment with this instrument was made at Mr, 

 Kier's manufactory, in the presence of many scientific gen- 

 tlemen. The piezora«ter, being perfectly filled with water, 

 (the weight of which was accurately known,) was put into 

 an hydraulic press, and subjected to a pressure of about 

 three hundred and twenty-six atmospheres. When it was 

 taken out and weighed, there was found an increase of water 

 amounting to three and a half per cent. This water had 

 been previously boiled, and cooled down to a temperature 

 of forty-eight degrees, and kept at the same temperature 

 during the experiment. 



A machine, calculated to avoid loss of pressure from de- 

 struction of the materials of which it is composed, will be 

 made with all convenient speed. This machine, being con- 

 structed with metallic stuffings and flexible metallic pistons, 

 will effect a much greater pressure than the hydraulic press, 

 the power of which is limited by the animal stuffing now 

 used. It is probable, a pressure of from two to three thou- 

 sand atmospheres may be obtained, before the metallic pis- 

 ton is destroyed. 



It is expected that this machine will be sufficiently accu- 

 rate to give the exact ratio of the compressibihty of water 

 with much greater precision than has hitherto been obtained; 

 but the results of farther experiments must be the subject of 

 a future communication, (e) 



29, Austin Friars, June 6, 1820. 



(e) The experiments described in this paper establish the important con- 

 clusion, that water continues to yield to a compressing- force, after it has been 

 rendered vastly greater than has been hitherto employed; but much remains 

 to be done, in order to give our views on this subject the extent and precis- 

 ion which it would be desirable to attain. The exact degree of condensation 

 by a given pressure, and the law of variation in the density for different 

 pressures, both remain in uncertainty. The experiments of Mr. Canton, 

 which seem entitled to much confidence, from the mode in which they were 

 •conducted, and which have the singular confirmation of explaining the 

 known velocity of sound in water, make the compression, by a single atmos- 

 phere, ■2 2'o"o'o'' Ml"' Perkins's last experiments give to each atmosphere an 

 average compression of g-gV o-- ^'^- Oersted, (Journal de Physique, October, 

 1818,) makes it 7-7V'o* Which of tliese deserves the most reliance ? To 

 reconcile the results of Mr. Canton with those of Mr. Perkins, we must sup- 

 pose the compressibility to increase as the pressure increases ; a supposition 

 contrary to the laws of all other elastic substances. — Should our ingenious 

 countryman continue to prosecute his researches on this subject, and extend 

 them to much higher pressures, as is promised in his concluding paragraph, 

 it woirld be pecnliarly desirable that the Imv of condensation by diBerent 



