12 EXPERIMENTS ON THE CARBONIC 
Humboldt concluded from some experiments 
that the air contained about 1 per cent of car- 
bonic acid gas. But Mr. Dalton found in his 
‘Enquiry into the properties of the several Gas- 
es constituting the Atmosphere.’ (see Memoirs, 
vol. 1, new series) that the quantity was only 
ii in volume, or ;, in weight; and since that 
time M. Saussure of Geneva has made abund- 
ance of experiments on the same subject, the 
results of which seem to shew that the quantity 
is somewhat less than that just assigned. 
M. Saussure’s method is to procure a large 
glass globe of known capacity, (one cubic foot 
or more) into which he passes a quantity of Ba- 
rytic water, more than sufficient to neutralize 
the carbonic acid in that volume of air. By 
agitation, the carbonic acid is united to the ba- 
rytes, forming an insoluble carbonate of the 
earth. The quantity of carbonate so formed 
being carefully ascertained, affords data for de- 
termining the quantity of carbonic acid. 
Mr. Dalton considers a globe of one fifth part 
of the size sufficiently ample, and uses Lime 
water of a known strength instead of Barytic, 
taking care to have more than enough to engage 
the acid gas; after the agitation and absorption 
