246 On Oxalic Acid. 



prevented any water from entering the tnbe. The experi- 

 ment was repeated three ti-ries. 



4. A hundred grains of oxalate of lime, when thus heated, 

 yield above sixty cubic inclies of a gas, which is always a 

 mixture of carbonic acid and inflammable air, nearly in tlie 

 proportion of one part of the former to three aiid a half of 

 the latter, reckoning bv bulk. The specilic gravity of the 

 intiammable gas was O'QOS, common air being rOOO; it 

 burns with a blue flame, and when mixed with oxygen may 

 be kindled by the electric spark. Tlie loudness of the re- 

 port depends upon the proportion of oxygen. 



The smallest f|uaniity of oxygen, with which it can be 

 mixed, so as to burn by the electric spark, is l-Qth; the 

 combustion is very feeble, and is attended with no percep- 

 tible report. If the residue be washed in lime-water and 

 mixed wiih 1 c,th of ;is bulk of oxygen, it may be kindled 

 a secoiid time : ^his may be repeated five times, after which 

 the residue cannot be made to burn. 



The combustion becomes more violent, land the report 

 louder, as Vv-e increase the proportion of oxygen, and both 

 are greatest when the oxygen is double the bulk of the gas. 

 As we increase the dose of oxygen, the combustion becomes 

 more and more feeble ; and five parts of oxygen and one of 

 gas is the limit of combustion on this side : for a mixture of 

 toix parts of oxygen and one of the inflammable air will not 

 burn. 



In these experiments the results difler materially from 

 each other, when the proportion of oxygen used is small 

 and when it is great. I am not able at present to account 

 for this difference, which holds not only with respect to this 

 gas, but every compound inflammable gas which I have 

 examined. This difference makes it impossible to use both 

 extremes of the series : I make choice of that in which the 

 proportion of oxygen is considerable, as upon the whole 

 more satisfactory. The best proportion is one part of the 

 a;as and two parts of oxygen. The oxygen ought not to be 

 pure, but diluted with at least the third of its bulk of azote, 

 unless the gas be much contaminated with common air. 



I have 



