207 
Cavendish’s full theory of the formation of water, which was not made 
public till January 1784, and which it could be shown by the Watt 
Correspondence De Luc did not become acquainted with till March 
of that year. 
Special attention was drawn to the fact, that the section of De 
Luc’s “ Idees” from which the quotation was taken went over the 
same ground as the Watt Correspondence. This section contained 
the matured and authoritative publication of those views on the rela- 
tive merits of Watt and Cavendish which are referred to by De Luc 
in the hasty private letters printed in the “ Correspondence” , in 
question, written when he was imperfectly informed on the points he 
was discussing, and not intended for publication. The author dwelt 
upon the omission of Mr Muirhead, when editing the Watt Corres- 
pondence, to point out this important fact to his readers, and the 
misleading effect of this omission in representing De Luc as much 
more the advocate of Watt’s claims than in reality he was. In 
many respects the “ Idees” supplemented the Watt Correspondence 
so far as the views of De Luc were concerned, and the latter work 
could not be understood unless read in the light of the former. 
The second of the recovered documents was an extract from a 
Report to the French Academy, on M. Seguin’s experiments on the 
Combustion of Hydrogen and Oxygen, dated 28th August 1790, 
written by La Place, in name of a Commission consisting, besides the 
reporter, of Lavoisier, Brisson, and Meusnier, all of whom sign it. 
The passage of most importance, as showing that Lavoisier aban- 
doned in favour of Cavendish the claim he at one time preferred to 
be the discoverer of the composition of water, is as follows : — 
“ M. Macquer a observe dans son Dictionnaire de Chimie que la 
combustion des gaz hydrogene et oxygene produit une quantite d’eau 
sensible ; mais il rfa pas connu toute 1’importance de. cette obser- 
vation, qu’il se contenta de presenter, sans en tirer aucune con- 
sequence. M. Cavendish paroit avoir remarque le premier que l’eau 
produite dans cette combustion est le resultat de la combinaison des 
deux gaz, et qu'elle est d’un pdids egal au leur. Plusieurs expe- 
riences faites en grand et d’une maniere tres-precise par MM. La- 
voisier, La Place, Monge, Meusnier, et par M. Lefevre de Gineau, 
ont confirme cette decouverte importante, sur laquelle il re doit 
maintenant rester aucun doute.” ( Annales de Chimie , tome viii.. 
pp. 258-9.) 
