From these two laws are deduced all the phenomena of chemical proportions. Sulphuric acid, for example, con tains as much oxygen as the base by which it is neutralized. Hence when any sulphate of a metallic oxyd is decomposed by another metal, the latter precipi tates the dissolved metal, under a metallic form, without altering its neutrality, because the sulphuric acid must, as formerly, contain three times the oxygen of the metal last dissolved, and therefore the oxygen remains without alter ation, nothing but the metallic radical being changed. Now, since the relation between the oxygen of the base and that of the acid is invariable, with regard to all neutral salts of the same acid, the constant ratio in the capacity of bases to saturate acids, observed and proved by Wenzel and llichter, follows as a necessary consequence from this fact; and such neutral salts as mutually decompose each other, must, therefore, still maintain their neutrality. If, on the contrary, which rarely happens, the ratio between the oxygen of the base and that of the acid is different for different bases, two neutral salts may happen, from this circumstance, to decompose each other, and at the same time lose their neutrality (as the muriate of glucina and the fluate of soda, the carbonate of potass and muriate of lime, sulphate of ammonia and muriate of barytes) with out however being in opposition to the above laws; for, in such cases, the oxygen of the base becomes a submultiple of that of the acid by a different number.
Yet the two principal rules, just mentioned, are not ab solutely without exception. Sulphur, in particular, forms an exception to the first. In the case of this substance we are acquainted with no more than two degrees of oxyda tion, the highest of which, sulphuric acid, contains but 12 time as much oxygen to the same quantity of sulphur, as the lower degree, sulphurous acid. The same is the fact with regard to iron. Antimony also has several degrees of oxydation, the second of which contains but 12 time as much oxygen as the first. It is quite possible, however, that these exceptions may be apparent only. They would, in fact, be so, should it be found that there are other low er degrees of oxydation not yet red, or not capable of existing in the isolated state. It is thus we have reason to consider sulphur, combined with oxymuriatic gas as being in the state of an oxyd, the oxygen of which, found by calculation, is exactly one half of that contained in sulphurous acid. If this is really the case, the degrees in which sulphur unites with oxygen are to each other as 1, 2, and 3. In like manner, the protoxyd of iron may con tain two times, and the protoxyd of antimony three times, as much oxygen as exists in some first degree of oxydation not yet discovered.
The exceptions to the second rule are fewer in number; but at the same time more striking and worthy of attention. In the greater part of those combinations among oxydized bodies hitherto analysed, none but the oxyds of two indi vidual radicals have been found to contradict this rule. The oxyds in question are those which have nitrogen and phosphorus as radicals. Nitrogen and phosphorus com bine with oxygen in different degrees, the last two of which are acids. In the case of other radicals, giving two acids, the ratio of the oxygen contained by the acid in its higher state of oxydation, to that contained by the acid in its low er state of oxydation, is as 2 to 3 ; in the case of nitro gen and phosphorus as 3 to 5. AI. Berzelius attempts to explain these deviations in the following manner. The composition of neutral nitrates is conformable to the rule so far that the acid contains five times as much oxygen as the base ; but the composition of subnitrates, three differ ent degrees of which he has examined, varies from it; the oxygen of the first subnitrate being a multiple by 21 of that contained by the base; in the second a multiple by 13; in the last a multiple by 1÷. Comparing these fractions with each other, and with the numerous analytical results, so exactly conformed to the rule, it would seem that some unknown circumstance has in this case produced an ex ception, not real but apparent. If the supposition, so long entertained, that nitrogen is not a simple body, be in truth well founded, these aberrations are capable of being easily and fully explained. One volume of nitrogen gas combines,
in its different oxyds, with 1, 1 and 21 volumes of oxy gen gas; from which it follows that if nitrogen really con tains oxygen, it can only contain half its volume; so that nitrogen would, on this supposition, be composed of one volume of a radical, unknown in its isolated state, and one volume of oxygen. Upon this hypothesis, the different de grees of oxydation which a volume of this radical admits, are produced by adding a volume of oxygen gas, according to the following series: 2, 3, 4, and 6; a series far more natural than the first. Now, as nitric acid contains six vo lumes of oxygen, the nitrates and subnitrates mentioned above no longer form exceptions to the rule; for in neutral nitrates the oxygen of the acid is six times that of the base; in the first two subnitrates three and two times that of the base; and finally, in the last subnitrate, the oxygen of the acid is equal in quantity to that of the base. This mode of viewing the composition of nitric acid becomes still more plausible, when the composition of ammonia is examined. This alkali has the closest analogy with the fixed alkalis, in all its properties, even in the method by which it is reduced to a metallic body in the circuit of the electric pile. Its composition must, therefore, in like man ner, be analogous to theirs; and if the former bear to the latter such a relation, for example, as the composition of acetic bears to the composition of sulphuric acid, we are naturally led to suppose in ammonia the existence of a quantity of oxygen capable of being calculated from the quantities of ammonia necessary for displacing, from its combination with an acid, another oxyd, the quantity of whose oxygen is known. In neutral carbonates, propor tional to the neutral carbonate of ammonia, the carbonic acid contains four times the oxygen of the base; while this carbonate of ammonia contains equal volumes of carbonic acid and ammoniacal gas. Now, since the carbonic acid gas contains a volume of oxygen gas equal to its own vo lume, the ammonia must contain a quantity of oxyg n equal to the fourth part of its volume. But in a volume of ammoniacal gas, the half is nitrogen; and, agreeably to what is said above, nitrogen ought to have the half of its volume (the fourth part of the ammonia's volume) com posed of oxygen gas; and thus our examination of ammo nia leads to the same conclusion with regard to the com position of azote, as the examination of nitric acid. In this way, it is easy to conceive how ammonia, by the action of the pile, may be decomposed into oxygen, and a body ana logous to metals, whilst the deoxydated radical of azote, combined with the hydrogen, is retained by its affinity to the mercury, which serves as a negative conductor. This reasoning, it cannot be denied, possesses considerable pro bability; and though nothing is proved by it, still it seems more likely that azote will be found to be a compound body than a simple one. As to the exceptions occurring in the case of phosphoric acid, a similar explanation would serve, if it were in our power to prove that phosphorus, like azote, contains oxygen. In neutral phosphates, the acid contains 21 times as much oxygen as the base; in sub phosphates 11 time as much.• If phosphoric acid, instead of 5, contained 6 portions of oxygen, one of them being concealed in the phosphorus, then the acid in neutral phosphates would contain three times as much oxygen as the base, in subphosphates two times as much. Al. Bc.rze lius combined phosphorus with iron, and caused the rod so obtained to be oxydated by muriatic acid; but he found that, in the phosphuret of iron, the phosphorus gives exactly the same quantity of phosphoric acid as an equal quantity of common phosphorus ; so that phospho rus either does not contain any oxygen, or combines with combustible bodies without losing it, just as the fixed alka lis and the earths, for instance, may combine with sul phur and boron, without losing their oxygen. For the present, then, it is proper to rest satisfied with observing and studying these exceptions, without pretending to the power of explaining or removing them.