in different Kinds of Gas. zia 



it would have been a little higher than that of common air, 

 becaufe it is fomcwhat lighter, and becaufe its gravity is to 

 that of atmofpheric air as 0-985 to i ; but it was half a tone 

 lower. Three kinds of azotic gas were tried ; one produced 

 bymeans of liver of fulphur, another by a mixture of iron 

 and fulphur, and the third from common air by means of 

 nitrous gas. 



In all the three a taper was extinguiflied in a moment, 

 and they all gave the fame tone. Should it be here fuf- 

 pefted that the azotic gas difengaged from atmofpheric air 

 by kilphur and iron, might have had a mixture of hy- 

 drogen gas, the tone in that cafe nnift have been raifed rather 

 than lowered by the latter on account of its lightnefs. We 

 may therefore confider it as certain, that the vibrations of 

 azotic gas, let it be prepared in whatever manner it may, 

 are much flower than the vibrations of atmofpheric air; and 

 that the dificrcnce amounts to about half a tone. It is re^ 

 niarkable that azotic gas in particular fliould exhibit, in re, 

 gard to its vibrations, fuch a variation from the common 

 theory, as, according to late experiments, it differs fo much 

 from other kinds of gafes in regard to its cxpanfibilitv at dif. 

 ferent degrees of heat. It would be well worth the' trouble 

 to repeat thefe experiments, refpefting the vibrations of azotic 

 gas, at different high and low degrees of temperature. It 

 ought alfo to be examined with more accuracy, whether 

 Marriot's law, that at the fame temperature the denfity of 

 an expanfible fluid increafes and decreafes in proportion to 

 us prefTure, may not admit of fome exception in regard to 

 azotic gas ; as this inquiry would, in all probability, enable 

 us to explain the variation of its vibrations from the com- 

 mon theory. 



A very remarkable phenomenon was exhibited by a mix- 

 ture of azotic and oxygen gas. It might have been fup- 

 pofcd, that azotic gas, being a lighter fubaance, would have 

 «ccafioned a higher tone than atmofpheric air 5 and oxygeji 

 T ^ gas, 



