On the Expansion of Elastic Fluids by Heat. £99 
pressure, expand to 1321 parts in the manometer’ . 
to which adding \4 parts for the corresponding 
expansion of ‘glass, ‘we ‘have 325 ‘parts increase 
Upon 1000 from’ 55° to’ 212°3! or for 157° of 
the thermometrie-@eale, As °for the expansion 
in the intermediate’ degrees, which’ Col. Rdi’s 
experiments shew to’bea Slowly diminishing one 
above the temperature of 57°, but ‘which de 
Morveau’s ‘on the-contrary shew tobe a rapidly 
increasing one in the ‘higher part of the scales -E 
am obliged ‘to. allow that ‘Col. ‘Roi is right, 
though it makes in some degree against an hy 
pothesis I have formed rélative to ‘the subject 3 
he ‘has certainly however made ‘the dimihution 
too great from 72° downwards, owing to ‘his 
not perceiving that he actually ‘destroyed a 
portion of the elastic fluid \he “was” operating 
upon (aqueous! Vapour) in reducing ‘its temper 
ature so low: if his air‘had been previously 
dried by sulphuric acid, &c. he would not have 
found so remarkable jdiminution below 72°. My. 
experiments ‘give for 772° above 55°, 167 parts 4 
forthe next 772° only 158 parts and the ex: 
pansion in every part of the scale seems to bea 
gradually diminishing one in ascending. 
The results of several experiments‘made upon 
hydrogenous gas, oxygenous gas, carbonic acid 
gas and nitrous gas, which were all the kinds J 
VOL. V. NN 
