S4«i CONTRACTION OF WATER BY HKAT\ 



bttaufethr that on fubjefting water to different degrees of temperature, 

 Jjpare°nt S denfity in inftrumerits made of different materials, he found the point 

 is different in of greateft derifity was indicated at a different temperature in 



different vcffels; • ■ • <-, 



vir. in earthen- ineaCh - 



ware at 34», In an apparatus, having a ball of earthen-ware, it was 



46%tndlc b ad fS at the SUh de S ree *» of g ldfs at the 42d 5 of brafs at the 

 £o». 46th; and of lead at the 50th. And as water could not 



follow a different law, according to the nature of the fubftance 

 of the inftrument, he conceived that the appearance of ano- 

 maly in this fluid originated entirely in the containing veflel, 

 which mil ft caufe the fluid in the ftem to fall or rife according 

 as its expanfions are greater or lefs than thofe of the included 

 liquor. 



A detail of thefe important experiments has, ere now, been 

 tranfmitted for publication in ihejounmh- of the Royal Ivptution 

 of London *. 

 Mr. Dalton I have already noticed that Dr. Hooke endeavoured to ex- 



Hooke" r * P^ am m the fame manner the original experiment of Dr. Croune. 

 This explanation apparently gathers much force from thefe ex- 

 periments of Mr. Dalton. 

 Dc Luc and It is proper, however, to flate, that M. de Luc was perfeclly 



aware of the alteration in the dimenfions of hisglafs apparatus, 

 but deemed the change loo trifling to have any material in- 

 fluence. 

 Blagdenwere Sir Charles Blagden paid greater attention to the eircum- 



vcffelT* ° fiance, and by calculation attempted to appreciate what allow- 

 ance ought to be made for the change of capacity in the amount 

 of the apparent changes of volume. 



When it isconfidered, that the whole amount of the apparent 

 change is but very fmall, and that the expanfibility of the glafs 

 is with difficulty afcertained, and is variable by reafon of the 

 fluctuating proportions of its heterogeneous confthuenls, it muff 

 be acknowledged, thatprecition in fuch a calculation cannot pot- 

 and various rea- fibly be attained,- and can fcarcely be approached. On this ac- 



fons afford count, all the experiments already noticed are ope'n to the 

 ground for • 



doubt. 'explanation of Dr. Hooke, and in fome meafure liable to the 



objection which he had urged. I confefs, that the experiments, 



of Mr. Dalton, in perfect concurrence with that explanation, 



* They were tranfmitted to our Journal by the author in Vol. X, 

 psge 93. 



Created 



