ON THE FOUL AIR OF OIL CISTERNS, gOQ 



A lighted candle on being let down into the ciftern, wa^ .'/| 'V,'^.^[ , 

 inftantly extinguifiied. 



The furface of lime-water, when included for a few 

 minutes in a broad vefTel, was flightly tinged with prifmatic 

 colours. 



To obtain the gas for experiments, bottles filled with water 

 were lowered into the cifierns, and emptied at various 

 depths. 



On the gas obtained from about two feet below the mouth Obfervations on 

 of the ciftern, the following experiments were tried t ^^^' 



J. A c^^lindrical veflel being filled with the gas, kept in 

 conta£l with lime-water, during fifteen days, with frequent 

 iliaking, caufed a fmall diminution in the bulk of the gas. 



2. The fame experiment repeated with ammoniac offered 

 a fimilar refuit. 



Thefe two experiments denote the prefence of carbonic 

 acid gas. 



3. The gas remaining from the two former experiments, 

 when put in contad with liquid hydrogenated fulphuret of 



- poiafb, underwent an abforption of eight centimes j which 

 muft have been oxigen. 



The gas taken within a foot of the bottom of the ciftern It contained 

 aflforded fimilar refults, only the proportion of carbonic acid "'"'"'""^ ^^"^* 

 gas was greater. That which remained after the efTeft of 

 reagents was azote, as the following phenomena prove. 



1. A lighted candle was extinguifhed by immerfion in the 

 gas at the upper part of the cylindric veflel ; but it remain- 

 ed burning if the veflel was previoufly opened Tor a few 

 feconds. 



2. The veflfel when reverfed lofl none of the gas contained 

 in it ; and the light was extlnguiflied when introduced. 



3. The luminous combuflion of phofphorus in oxigen gas 

 (the formation of nitric acid with this gas and oxigen gas not 

 having been tried) was confidered a pofitive proof of its 



nature. f ' 



This noxious gas was found to contain, 



Upper Part, Lower Part, Analyfi*. ^ 



Azotic gas - - 86 Azotic gas - - 80 



Oxigenated gas - - 8 Oxigenated gas - - 6 



Carbonic acid gas • 6 Carbonic acid gas - 14> 



100 100 



S 2 The 



