<>26 MAXIMUM DfiNSlTY OF WATEK. 



It was firft an- The fundamental fa6t on which ihe fuppofilion is grounded, 

 nouncedbyDe ^,|^j(.{, ^,^5 announced many years ago by Mr. De Luc J 

 namely, ihal the temperature at which the denfity of water is 

 • a maximum, is confiderably higher than that at which that fluid 

 freezes, is indeed fo very extraordinary, and appears to be the 

 caufe of fo many interefting phenomena, that too much pains 

 cannot be taken to pal it beyond doubt. 

 New method of As the^methods hitherto ufed for determining that important 

 proving It. point have, by fume at lead, been confidered as infufficient, 



J liiall lake the liberty to propofe another, by which the fa6t 

 in cjueltion may, I think, be demonftrated dire6^Iy ; and with- 

 out any nice calculations, or any very difficult or delicate ex- 

 periments. 



Let the following experiments, (which it will be eafy to 

 repeal) fpeak ibr themfelves. 

 Api>aiatus. In Having provided a cylindrical veffel, (A Fig. L Plate XIL) 

 th ^middle Ota q^^^^ above, made of thin (lieet brafs, which is 5~ inches in 



thin cvlindncal ' ' , . , , , , n i 



biafs veil'el, a diameter, and tour inches deep, fupported on three ftrong legs, 

 tiin krafs cup j i inches high ; I placed in it a thin brafs cup, (B) two inches^ 

 in diameter at its bottom, (which is a little convex down- 

 wards) 2 /o inches wide at its brim ; and I -5% inches deep j 

 which cup (lands on three fpreading legs made of flrong brafsr 

 wire, and of fuch form and length, that when the cup is in- 

 troduced into ihe cylindrical velTel, it remains firmly (ixed in 

 the axis of it, and in fuch a titualion, that the bottom of the 

 cup is elevated juft I J inches above the bottom of the cylin- 

 drical vefl'el. 

 In the middle of In the middle of this cup there Hands a vertical tube of 

 fu ortcd^"^ '^ *^*" flieet brafs, | an inch in diameter, and -5% of an inch in 

 length, open above, which ferves as a fupport for another 

 fmaller cup (C) which is made of cork; the brim of which is 

 on the fame horizontal level with the brim of the larger brafs 

 Clip, ill which it is placed, 

 an heoiirpherical This cork cup, which is fpherica), (being fomething lefs 

 cup oi coik, t},an half of an hollow fphei«) is one inch in diameter at its 

 brim, meafured within -j+g of an inch deep, and I of an inch 

 in thicknefs. It is firmly attached to the vertical tube on 

 which it ftands, by means of a cylindrical foot, J an inch in 

 diameter, and | of an inch high ; which, when fome force is 

 employed, enters into, the opening of the vertical t^be. 



