in different Kinds of Gas. 281 



third. This dlfierence,. however, is not fo great as might 

 have been expected from fo light a gas, the gravity of v.hich 

 is to that of common air, when the gas is perfeilly pure, as 

 0-084 to I. Had the tones, therefore, been inverfely as the 

 fquare roots of the gravity, the tone with hydrogen gas from 

 iron and the fidphuric acid, allowing it to have been only 

 fix or feven times lighter than atmofpheric air, muft have 

 been about an odave and a large third higher ; and by the 

 lighter hydrogen gas, about an odave and a I'niall fcvcnth 

 higher. Bv mixing atmofpheric air with hydrogen gas, the 

 tone, as might readily be expe6led,was lowered ; but it is to 

 be remarked, that as long as thefe two fluids were not uni- 

 formly mixed by filling and compreffing the bladder, a dlf- 

 cordant noife only was heard, and not a diftinft found, as 

 ihe vibrations coukl not be ifochronous, which forms the 

 only eflentlal difference between a diftinft found and iuch a 

 difcordant noife. Tlie fame thing was obfervcd in regard to 

 the bCTore-mentioncd mixture of azotic and oxygen gas. 



The tone of carbonic acid gas from chalk and tb.c fiJ- 

 phuric acid was almoft a large third lower than the tone of 

 atmofpheric air; which agrees pretty well with theory, fmce 

 the gravity of thefe fluids is as 1-5 to i. 



Nitrous gas from nitrous acid and copper was not very 

 favourable to found ; and it required a ftrong preffure of the 

 bladder and a gre^t deal of caution, becaule, inftcad of the 

 wiflied-for low tone, one of the higher tones was produced. 

 The lowcfi: tone, obtained with confiderable difiiculty, was 

 about half a tone lower than in atmofpheric air; vvhicli agrees 

 alfo pretty well wldi theory, fince this gas is heavier, and 

 the gravities are as I-I95 to i : the tone was alfo almoft like 

 that in azotic gas, notwlthltanding the confiderable differ- 

 ence in the gravities of thefe two fluids. 



As to the velocity with which the found of another claflic 

 ibody would be conduced through thefe gafes, could a fufll- 

 cicnt extent of them be procured to make the obfervation, it 

 follows, from what has been faiJ in the beginning of this 



paper, 



