VOL. LXV.] 



PHILOSOPHICAL TRANSACTIONS- 



011 



experiments relative to the freezing of boiled water, in comparison with that of 

 water not boiled. I ordered some water to be boiled in the tea kettle 4 hours. 

 I then filled with it a Florentine flask, and immediately applied snow to the 

 flask, till I cooled it to 48° of Fahrenheit, the temperature of some unboiled 

 water which stood in my study in a bottle ; then putting 4 oz. of boiled, and 4 

 of the unboiled water, separately, into 2 equal tea cups, I exposed them on the 

 outside of a north window, where a thermometer pointed to 29°. The conse- 

 quence was, that ice appeared first on the boiled water ; and this, in several 

 rejjetitions of the experiment, with the same boiled water, some of which were 

 made 9 hours after it was poured out of the tea kettle. The length of time 

 which intervened between the first appearance of ice on the 2 waters, was 

 different in the different experiments. One cause of this variety was plainly a 

 variation of the temperature of the air, which became colder in the afternoon, 

 and made the thermometer descend gradually to 25°. Another cause was the 

 disturbance of the water ; when the unboiled water was disturbed now and then by 

 stirring it gently with a quill tooth-pick, the ice was formed on it as soon, or very 

 nearly as soon, as on the other ; and from what I saw, I have reason to think, that 

 were it to be stirred incessantly, provided at the same time the experiment were 

 made with quantities of water, not much larger or deeper than these, it would begin 

 to freeze full as soon. In one of these trials, having inspected my tea cups 



during 1798 and 1799 ; and on the 26'th of Nov. of the last-mentioned year he expired suddenly, 

 while at table, with his usual fare, some bread, a few prunes, and a measured quantity of milk 

 diluted with water. He had the cup in his hand when the last stroke of his pulse was to be given, 

 and had set it down on his knees, which were joined together, and had kept it steady with his hand, 

 in the manner of a person perfectly at his ease : and in this attitude he expired, without spilling a 

 drop, and without a writhe on his countenance. His servant thought he Ixad been asleep. Thi» 

 euthanasia happened when he was in his 7 1 st year. 



When we take a view of Dr. B.'s experiments on magnesia and quicklime proving that th« 

 causticity in burnt lime and alkalies, is owing to their being deprived of fixed air (carbonic 

 acid) with which they are combined in their mild state ; and of the experiments which he mado 

 on the conversion of water into steam, showing the diflFerence between sensible and latent heat, 

 (in which originated the great improvements made by his pupil Mr. Watt in that admirable and 

 most usefial mechanical apparatus, the steam engine) when we take a view of these experiments, 

 fi^m whence as, from a centre, have radiated the brilliant discoveries in pneumatic chemistry 

 of several contemporary philosophers, we shall be fiilly satisfied that they who have pronounced 

 Dr. B. to have been one of the greatest chemists of the ISth century, have by no means over-rated 

 his scientific character. 



Besides his inaugural dissertation De Acido a Cibis Orto, and liis Experiments on Quicklime above- 

 mentioned, and the present paper in the Phil. Trans., Dr. B. published an Analysis of the Waterf 

 of some Boiling Springs in Iceland, (see the Trans, of the r. s. of Edinburgh). And aftsr his death 

 the worid was favoured with the publication of his Lectures on Chemistry, in 2 vob. 4to., 1803, 

 by his intimate friend Mr. Robison, Professor of Natural and Experimental Philosophy in Edin» 

 burgh J from whose and Dr. Ferguson's account of the author, the above particulars have been takeu. 



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