Chemistry and Physics. 421 
5. The Discovery of the Composition of Water, (Athen., No. 1635, 
Feb. 26, 1859).—Mr. Bennett, of the British Museum, has addressed a 
letter to Sir Benjamin Brodie, Bart., which contains indisputable evidence 
in favor of Cavendish’s claim to the discovery of the composition of water. 
The evidence was discovered by the late Robert Brown, Esq., and is not 
derived from any unpublished document, but forms part of a section of 
Cavendish’s claims. It is the more conclusive as coming from De Luc, 
the “ami zélé,” as he justly terms himself, of Watt, and who, in relation 
to this question, believed himself “a portée d’en connoitre toutes les cir- 
constances.” 
The testimony of De Luc is as follows :—* Vers la fin de l’année 1782, 
jallai a Birmingham, oi le Dr. Priestley s’étoit établi depuis quelques 
années, I] me communiqua alors que, M. Cavendish, d’aprés une remarque 
de M. Warltine, qui avoit toujours trouvé de l’eau dans les vases ou il 
avoit brilé un mélange de [air inflammable et d’air atmosphérique, 
sétoit appliqué & découvrir la source de cette eau, et. qu’il ayoit trouvé 
qun mélange dair inflammable et d'air déphlogistique en proportion 
convenable, étant allumé par I’étincelle électrique, se convertissoit tout 
ener en eau.—Je fus frappé au plus haut degré de cette découverte.” — 
ées sur la Météorologie, Tome 2, 1787, pp. 206-7. 
The italics and inverted commas are De Luc’s own. 
Ih this communication, made by Cavendish to Priestley, the theory of 
the composition of water is clearly indicated. e two gases—known to 
lave been hydrogen and oxygen—were mixed together in due proportion, 
and by means of the electric spark were entirely converted into water. 
Referring to one of Cavendish’s experiments, as recorded in his Journal, 
Lord Jeffrey, the most candid and. judicious. of Watt's advocates, has 
said, “If he (Cavendish) had even stated in the detail of it that the airs 
Were converted, or changed, or turned into.water. it would probably a 
eae he could prevail on his. modesty to claim. it < giome 
7, p. 125. ; hen 
The evidence which this distinguished critic and judge regarded ” a 
ficent to establish Cavendish’s.claim is now afforded, not by.a note in his 
Phvate journal, but by the testimony of. the zealous friend of Watt, who 
that it was i 
} remain uncon’ 
moreover, published to the world and suffered ee with the author 
Itisa remarkable fact that notwithstanding all the recapepenec 
®t many occasions during the past halfcentury on De, SE 
Corery of the composition of water, and. even witlun the, Zaaeyont “4 
‘minent savants, the evidence published. by.De.Luc, i ae te t 
Undiscovered, with an_exception,. that being, as above mentioned, the fis 
Robert: Brown, Esq., and this is the more.remarkable when. we remem 
