go NATURE OF OXIGEN, HIDROGEN, CALORIC, &C. 



that the urine of men contains phofphate of magnefia, and that 

 the urine of animals is free from it. This fait is therefore 

 ejected in man, by the kidneys; it therefore does not enter 

 into the compofition of bones; moreover the urinary calculi 

 of man frequently contain phofphate of ammonia and magne- 

 fia, but no fuch falts are ever found in the fiony concretions of 

 the intefiinal canal. 



IX. 



On the Nature of Oxiqen, Hidrogen, Caloric, S^-c, as deduced 

 from Gidvanic Experimevii. Bj/ A CoRREsroNDENx. 



On the exiftence v>INCE we are told that oxygen is one of the moft eflential 

 ox oxigen. Tubftances in the production of the moft ftriking phenomena 

 of nature; that heat and light refuU from its change of com- 

 bination, nay, that animal life is dependant on it, it becomes 

 a matter of very great utility to inveftigate its nature, much 

 more to prove whether it has any exiftence. It is well known 

 that this fubftance, which has now fo long and (b generally been 

 admitted, has never yet been exhibited except in combination, 

 and that the evidence of its exiftence in combination has never 

 been more than prefumptive. It appears from fome late ex- 

 periments io4)e poffible to fubftitute known for unknown prin- 

 ciples, and to relieve fcience !rom thofe agents which are 

 merely hypothetical. 

 Oxigen and hi- The wires from the galvanic combination of metals produce 

 drogeii take., to aifferent effeas when placed in (he fame vetTelof water. One 



he water with . . 



the power from produces inHammable air, the other vital air. When ihe cir^ 

 tach rcfpeftive cuit is made by the human body, a fliock fimilar to an electrical 

 vanic wire. ' **"^ ^^ perceived. It therefore appears that thofe powers 

 which thus affed the jniman body, change water into inflam- 

 mable and vital air. One wire always produces one air, and 

 the other wire another air from water. I^ it not therefore 

 philofophical to refer the production of one oFthefe airs to the 

 power proceeding from one end of the pile and water; and the 

 produ6lion of the oiher air to the power proceeding from the 

 other end of the pile and water? In this experiment we are 

 made fenfible of no other principle, power, or fubftance than 

 the above-mentioned. Why (liould we therefore have recourfe 

 10 two hypothetical fubftances, oxygen and hydrogen, which 



have 



