On the Discovery of the Composition of Water. 141 



Gluten, caseine, gelatine, albumen, and fibrine increased the amount 

 of carbonic acid exhaled, the two former to about 1 grain per minute, 

 and the last to about \ grain per minute. Almond-emulsion did 

 not increase it. 



From these facts the author infers that there is a class of foods 

 which might be called " excito-respiratory ;" a class which embraces 

 nearly all nitrogenous foods, and is almost entirely composed of these 

 substances. 



T\\e non-excitants are starcli, fat, some alcohols, and coffee-leaves. 



The respiratory excitants are sugar, milk, the cereals, jjotato, tea, 

 coffee, cliichory, cocoa, alcohol, rum, ales, some wines, gluten, caseine, 

 gelatin, fibrin, and albumen. 



Of the hydrocarbons, sugar acted very differently from starch and 

 fat. 



All the "respiratory excitants" increased the depth, but not the 

 rate of respiration. 



Some of them acted with great rapidity ; as, for example, sugar 

 and tea, which sometimes caused an increase of 1 grain of carbonic 

 acid per minute in from five to eight minutes. Others, as gluten 

 and caseine, acted with less rapidity. In many, as tea and gluten, 

 there was not a proportionate increase in the carbonic acid with in- 

 crease in the quantity of the "excitant." Some of them, as tea, 

 produced much greater effect when a small dose was frequently 

 repeated, than when the whole quantity was given at once, and 

 caused a much greater evolution of carbon than they supplied. The 

 duration of the increase was very different with different foods, but 

 that with sugar was the least, and then that with tea, while that 

 with the cereals and rum and milk was the greatest. The amount 

 of carbonic acid progressively increased at each examination until 

 the maximum was attained ; after which it remained nearly sta- 

 tionary for some time, as with the cereals, or subsided rapidly to the 

 basis quantity, as with sugar. 



February 17 — Sir Benjamin C. Brodie, Bart., President, in the Chair. 



The following communications were read : — 



•' Statement of Facts relating to the Discovery of the Composition 

 of Water by the Hon. H. Cavendish." In a Letter from J. J. Ben- 

 nett, Esq., F.R.S., to SirB. C. Brodie, Bart., P.R.S., dated February 

 12, 1859. 



Since the death of our late excellent and lamented friend Mr. 

 Robert Brown, several appeals have been made to his executors to 

 publish certain evidence presumed to have been in his possession 

 relating to the much-agitated question of the priority of Cavendish 

 or Watt in the discovery of the composition of water. As tlie execu- 

 tor to whom Mr. Brown entrusted his papers, and having been for 

 many years honoured with his entire confidence, I feel called ujiou 

 to respond to these appeals, and I therefore request that you will 

 kindly lay before a Meeting of the Royal Society the following brief 

 statement on the subject. 



The date and nature of Cavendish's communication to Priestley 



