377 



some observations respecting the different quantities of uric acid 

 voided by birds living upon different kinds of food, not being pro- 

 duced by those that live entirely upon fish. 



Researches on the oxymuriatic Acid, its Nature and Combinations ; and 

 on the Elements of the muriatic Acid. With some Experiments on 

 Sulphur and Phosphorus, made in the Laboratory of the Royal In- 

 stitution *. By H. Davy, Esq. Sec. R.S. Prof. Chem. R.I. F.R.S.E. 

 Read July 12, 1810. [Phil. Trans. 1810, p. 231.] 



The tendency of the author in the present investigation, is to re- 

 turn to the opinion respecting the relation of muriatic acid and oxy- 

 muriatic acids to each other, which was originally entertained by 

 Scheele. 



According to that most illustrious chemist, the oxymuriatic was 

 the more simple body, and by union with phlogiston became muriatic 

 acid. But from many experiments made soon after by Berthollet, it 

 was inferred that the latter was simple, and by union with oxygen 

 became converted into oxymuriatic acid. In Mr. Davy's former at- 

 tempts to obtain the base of muriatic acid by potassium, he has not 

 been able to separate anything from it but hydrogen. In Dr. Henry's 

 endeavours by electricity to decompose the muriatic acid, hydrogen 

 and oxymuriatic acid were evolved ; and conversely, Mr. Davy has in 

 no instance been able to separate oxygen from oxymuriatic acid, or 

 even to separate muriatic acid from dry muriates, without the assist- 

 ance of hydrogen or water. He has hence been led to doubt the 

 existence of oxygen in the substance called oxymuriatic acid, and 

 has applied the most powerful means of abstracting oxygen from it 

 without success ; and indeed Messrs. Gay-Lussac and Thenard, in 

 their elaborate and interesting experiments, published in the Me- 

 moires d'Arcueil, although they maintain that muriatic acid gas con- 

 sists of muriatic acid and water, are not able to separate water from 

 it, but only hydrogen ; and themselves acknowledge that oxymuriatic 

 acid, which they suppose to consist of muriatic acid and oxygen, can- 

 not be decomposed by any known means. 



The most extraordinary fact noticed by Mr. Davy is, that when 

 charcoal is ignited to whiteness by the voltaic battery in oxymuriatic 

 acid gas, no change whatever is produced, provided that the charcoal 

 has been previously freed from moisture or from hydrogen by intense 

 heat. 



The vivid combustion of many bodies in this gas has favoured the 

 presumption that it contained oxygen very loosely combined and 

 ready to exert its utmost power of affinity : but it is mere presump- 

 tion ; since heat and light result also from the intense agency of any 

 other combination, without the presence of oxygen. 



The resemblance of oxymuriatic acid combined with metals to 

 other neutral salts, may be considered a strong argument in favour 



* Communicated to the Royal Society at the request of the Managers of the 

 Royal Institution. 



