Dana on Nitrous Gas. 339 
ble difference in the quantity of oxygene contained in the 
air in different places, even in situations most favorable for 
producing decided differences, provided no uneasiness is 
produced by the respiration of such air. “Phe experiments 
iron; Dalton affirms that, if dilute oxygene gas and dilute 
i i a 
or much less oxygene than 21 per cent. It is unnecessary 
to refer to any other method of using this gas in eudiome- 
try than that proposed by Gay Lussac ; a method which is 
pteferable to any other, since it affords uniform results. — It 
is almost unnecessary to say, that the method consists in 
introducing a portion of air previously measured in a grad- 
uated tube, into a wide vessel, like a tambler, over water, 
re 
vapours are produced ; the mixture is suffered to stand one 
minute and then transfered to the graduated tube, and the 
diminution in volume noted; this divided by 4 gives the 
quantity of oxygene. The diminution, if 100 parts of air 
and of nitrous gas be used, will be nearly 94 parts; and 
+4 als of this method, there has 
between the results, and those 
as, has never yet been explaine 
authors uniformly aseribe tt to t 
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