proofs of the laws of chemical affinity.

59

combination, is divided between the two remaining not only inproportion to their respective degrees of affinity, but also accord-ing to their ponderable quantities, so that by varying this in ei-ther, the effect produced will be varied.

Thus Berthollet has proved, that in all cases a large quantityof a body, is capable of abstracting a portion of another, from asmall portion of a third, how weak soever the affinity betweenthe first and second of these bodies may be, and how strong so-ever the affinity between the second and third. Thus potash iscapable of abstracting part of the acid from oxalate of lime, phos-phate of lime, and carbonate of lime. Soda and lime, decomposepartially sulphate of potash. Nitric acid subtracts part of the basefrom oxalate of lime, See.

The following experiment advanced by Berthollet will provethis more clearly.

PROOFS OF I AW VIII.

Experiment I.

If equal parts by weight, of sulphate of barytes and potashbe boiled in a small quantity of water to dryness, it will be foundthat the sulphuric acid has been divided between the two basesin the compound ratio of their mass, and their force of affinity.The greater part of the sulphate of baiytes will be foundundecomposed; a small quantity of barytes will be found atliberty ; most of the potash will also be uncombined, but a cer-tain portion will be united with the sulphuric acid which thebarytes has lost, in the form of sulphate of potash.

It is not merely in the instance stated here that this divisionof one body between two others according to their respectivemasses and affinities takes place, there being scarcely any exam-ple to the contrary.

And as the affinities of bodies vary with their masses, it is ob-vious that when we speak of the affinities of bodies, we ought toconsider them as always acting in certain determinate proportions.