330 LAVOISIER. 



out the presence of oxygen or if oxygen be present 

 in some of these cases, it is not operative in any way 

 it is not disengaged, and is not in the form of a gas 

 to be absorbed. Thus, much heat is caused by the 

 mixture of sulphuric acid and water ; some heat by the 

 mixture of alcohol and water. Lime when slaked by 

 water produces violent heat, sometimes accompanied 

 with light also, flame as well as redness appearing. The 

 union of iron with sulphur in vacuo causes great heat 

 and the emission of bright light. The exposure of 

 metals and other inflammable bodies to gases which 

 contain no oxygen, as chlorine, produces red heat and 

 flame. Therefore, although it is very true that we 

 know of no instance in which combustion takes place 

 without the union of the combustible body to some 

 other, and the formation of a new substance, yet it is 

 not true that oxygen alone causes combustion, and 

 that no body can burn but in oxygen gas. 



Secondly. The facts are all against his doctrine, that 

 the heat and light comes from the fixation of the gas. 

 Experiments on the capacity of bodies for heat have 

 clearly shown this. But the simple fact of well-known 

 explosions, as of gunpowder, disproves his theory for 

 here, instead of the heat and light coming from the gas 

 being reduced to a solid state, a gaseous body is formed 

 two or three hundred times the bulk of the solid ex- 

 ploded. 



Thirdly. There are many acids which have no 

 oxygen in their composition, and there are many 

 bodies containing oxygen which have none of the 

 qualities of acids. The first part of this proposition 

 was not certainly known to Lavoisier, and he assumed 

 that the acids which had not yet been decomposed 

 would be found to contain oxygen. The second part 

 of the proposition was known to him, and ought to have 

 checked his generalization. We now know many 

 acids which contain no oxygen at all. Muriatic acid, 

 a compound of chlorine and hydrogen ; prussic acid, a 



