B36 On the Constitution of mixed Gases, Se. 
ments lately engaging my attention some new 
facts have been ascertained, which with others, 
seem to authorise the deduction of general laws, 
and such as will have influence in various 
departments of natural philosophy and chemistry. 
As the detail of experiments will be best un- 
derstood and their application seen, if the laws 
of principles alluded to be kept in view, it may 
be proper here to state them; though it must not 
be understood that they were proceeded upon 
hypothetically in the direction of those experi- 
ments- On the contrary, the first law, which is 
as a mirror in which all the experiments are best 
viewed, was Jast detected, and after all the par- 
ticular facts had been previously ascertained. 
1. When two elastic fluids, denoted by 4 
and B, are mixed ‘together, there is no mutual 
repulsion: amongst their particles; that is, the 
particles of .4 do not repel those of B, as they 
‘do one another. Consequently, the pressure 
or whole weight upon any one particle arises 
solely from those of its own kind. 
2, The force of steam from all liquids is the 
same, at equal distances above or below the seve- 
‘ral temperatures at which they boil in the open 
air: and that force is the same under any pres- 
sure of an other elastic fluid as it is in vacuo, 
“Thus, the’ force of aqueous vapour of 912° is 
equal to go inches of mercury; at 30° below, or 
