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Tlie respective proportions of potash andbarytes that saturate any acid are always as173:281, and in the decomposition here as-sumed the muriatic acid that saturates thesebases is 100 parts. Therefore the sulphuricacid must be 149 parts as calculated both fromthe elements of sulphat of potash and sulphatof barytes, In the former case 116 of potashsaturate 100 parts of sulphuric acid, and116 : 100 :: 173 : 149. In the latter case 190of barytes saturate 100 of sulphuric acid, and190 : 100 :: 281 : 149.

The importance of this law of chemical com-bination is so great that the composition of allthe binary compounds might be found with ab-solute certainty, provided the data founded onactual experiment could be brought to perfectaccuracy. Hitherto however this has not beenthe case, as no series of numbers representingthe neutral compounds has yet been givenwhich will apply throughout. It is a chief part•of the present labours of Prof. Berzelius tocorrect the elements of these calculations byvaried experiments conducted with great careand intelligence.

Another equally important law laid down byRichter is, that when the metal of a neutralmetallic solution is precipitated by another me-tal, it is the metallic base alone which is changed,the oxygen and the acid remaining united withthe last added tnetal. Hence it follows that allthe different metallic oxyds which saturate adefinite portion of acid contain the same quan-tity of oxygen. Or in other words it may beexpressed that a given quantity of any acidcombines to saturation with only a definite pro-portion of oxygen united to so much of anybase as contains this-portion of oxygen. Thusfor example, if 100 parts of sulphuric acid sa-turate 20 parts of oxygen and the base unitedwith it, the proportion of every oxyd that com-bines with 100 of sulphuric acid, and the com-position of every neutral sulphat is known assoon as the oxyd itself is analyzed. And, con-versely, the composition of any unknown oxydmay be discovered by finding the quantity ofthis oxyd which neutralizes a given weight ofany acid whose saturating quantity of oxygenin any other oxyd is previously known. Thus,for example, if 100 parts of sulphuric acid satu-rate any oxyd that contains 20. of oxygen, itmay be inferred that 116 parts of potash arecomposed of 20 of oxygen and 96 of potassium,since this quantity of potash saturates 100 ofsulphuric acid. The like quantity of oxygen istherefore contained in 78 of soda, in 190 of

barytes, &c. &c. each of which saturate 100 ofsulphuric acid.

The late discovery of the compound natureof the alkalies and earths therefore gives anadditional importance to this Jaw of chemicalaffinity.

Another law of chemical combination whichis laid down by Berzelius, and illustrated bynumerous examples, is the following, viz. Inany compound of two oxydated substances, thatsubstance which is attracted to the positive poleof the electric circuit (the acid, for example)contains as much oxygen as is produced by-multiplying the oxygen of the substance at-tracted to the negative pole (such as alkali,earth, metallic oxyd) by some of the integralnumbers 2, 3, 4, 5, &c. For example, as 100parts of sulphuric acid saturate as much of anyoxyd as contains about 20 parts of oxygen, thequantity of oxygen in 100 parts of the acid it-self must be equal to twice 20, or three times20, &c. In this example it will be shewn pre-sently that sulphuric acid contains almost ex-actly three times 29, or 60, per cent, of oxygen.Most of the other acids iiowever contain onlytwice the oxygen of their saturating base : thecarbonic and sulphureous acids are of this kind.

In all the compounds in which water formsan element (which are all the crystallized saltsand liquid acids) this substance also seems tobe subjected to some similar law of definiteproportion, as will be soon explained.

We shall now give a short abstract of a fewof the important series of Prof. Berzelius’ ex-periments, to shew to what degree they illustrateand confirm the above laws of chemical combi-nation, together with some others which wilLbe stated in their place.

The composition of sulphuric acid which hasso often been attempted was ascertained in se-veral methods; and first through the medium-of the oxyd and sulphuret of lead.

Lend and Oxygen.' Lead has three degreesof oxygenation, viz. the yellow, the red, and !the brown.

For the yellow -oxyd, some pure lead (re-duced from the nitrat of lead) was dissolved innitric acid evaporated and ignited; a hundredparts of metal thus gained 7.8 of oxygen.

The red oxyd, or purified minium, containsto 100. of metal 11.07 oxygen.

The brown oxyd formed by digesting mini-um in nitric acid, contains to 100. of metal-15.6 of oxygen.

Therefore these portions of oxygen, viz. 7.8;

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