180 



PROPORTIONS DETERMINATE. 



carbonate of ammonia contains equal volumes of car- 

 bonic acid and ammoniacal gas. Now, since the car- 

 bonic acid gas contains a volume of oxygen gas equal to 

 its own volume, the ammonia must contain a quantity 

 of oxygen 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) composed of oxygen gas; and 

 thus our examination of ammonia leads to the same 

 conclusion with regard to the composition 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 analogous to 

 metals, whilst the deoxidated radical of azote, combin- 

 ed with the hydrogen, is retained by its affinity to the 

 mercury, which serves as negative conductor. This 

 reasoning, it cannot be denied, possesses considerable 

 probability ; and though nothing is proved by it, still 

 it seems more likely that azote will be found to be a com- 

 pound body than a simple one. As to the exceptions 

 occurring in the case of phosphoric acid, a similar ex- 

 planation would serve, if it were in our power to prove 

 that phosphorus, like azote, contains oxygen. In neu- 

 tral phosphates, the acid contains 2^ times as much 

 oxygen as the base; in sub-phosphates lg 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, 

 hi subphosphates two times as much. M. Berzelius 

 combined phosphorus with iron, and caused the rod so 

 obtained to be oxidated by muriatic acid ; but he 

 feund 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 

 phosphorus either does not contain any oxygen, or 

 combines with combustible bodies without losing it, 

 just as the fixed alkalies and the earths, for instance, 

 may combine with sulphur and boron, without losing 

 their oxygen. For the present, then, it is proper 

 to rest satisfied with observing and studying these ex- 

 ceptions, without pretending to the power of explain- 

 ing or removing them. 



What has now been said relates merely to the facts 

 observed. In chemical philosophy it is farther requi- 

 site to try if an account can be given why the facts 

 are thus -and not otherwise. Some memoirs of M. 

 Berzelius have had in view to examine the cause 

 of chemical proportions. " Whenever we begin to 

 consider this matter," he observes, " it is evident, at 

 first sight, that the cause cannot be any thing else than 

 of a mechanical nature ; and the idea, which seems 

 most probable and best suited to the views suggested 

 by experience, is that bodies are composed of molecules 

 or atoms, which combine one with one, 1 with 2, 3, 4, 

 &c. : and the laws of chemical proportions appear to 

 result from this principle, in a manner so clear and 

 evident, that it seems strange how an idea so simple 

 and rational should have failed, not only to be adopt- 

 ed, but even to be stated till our own age/' This hypo- 

 thesis gains an additional degree of credibility when 

 applied to those electro-chemical facts, by which we 

 have just learned that all the phenomena of affinities 

 are, in truth, nothing more than phenomena of an elec- 

 tric action, between the bodies mutually combined or 

 decomposed. ' Supposing those atoms or elementary 

 molecules, of which bodies are formed, to be endowed 



with an electric polarity, by which their affinities are 

 exercised, we are enabled to comprehend how the 

 forces, named chemical affinities, may be the same as 

 the two opposite electric states, named -f- E and E. 

 By this means, the phenomena of chemical proportions 

 will not be difficult to understand, if we admit that mo- 

 lecules combine one atom or molecule with one or seve- 

 ral elementary molecules ; and a corpuscular theory that 

 shall not omit the forces on which the combinations of 

 molecules depend, will henceforth constitute the basis of 

 chemistry and physics ; whether, in fact, this theory 

 be a true exposition of the nature of things, or only a 

 mode of representation, enabling us to know and com- 

 prehend what otherwise must have remained inexplica- 

 ble and undiscovered. Now, if experience has begun 

 to ratify such a representation of the intimate composi- 

 tion of bodies, the second step will be to attempt dis- 

 covering the number of molecules belonging to each 

 element in each combination. Researches of 'this kind 

 are doubtless extremely difficult, their first results will 

 perhaps at best be doubtful, yet still it is plain, that 

 any supposition as to this point, if taken up at hazard, 

 cannot have the smallest value. Mr. Dalton was the 

 first who attempted to compute the molecules of the 

 elements existing in several compound inorganic bodies. 

 He set oiit, on this investigation, from a principle alto- 

 gether artificial. We have already mentioned, that, 

 when there is but one known combination of two ele- 

 mentary bodies, Mr. Dalton considers it as containing 

 a molecule of each element; but that when there are 

 two or more combinations, he allows himself to be 

 guided by the proportion subsisting between them. 

 Experience, however, daily shows that we are not yet 

 acquainted with all the degrees of combination ; and 

 when it happens that of several possible degrees of 

 combination we have discovered but a single one, no- 

 thing can assure us that this must be precisely the de- 

 gree, which contains only a single molecule of each of 

 its elements. It is impossible then, according to Ber- 

 zelius, that Mr. Dalton's application of the corpuscular 

 hypothesis can ever give satisfactory results. To dis- 

 cover the number of molecules in oxidized bodies, M. 

 Berzelius made use of two circumstances. He examin- 

 ed () the different degrees of oxidation in some one 

 radical. Suppose that of the several possible oxides of 

 this radical, but two are known ; their quantities of 

 oxygen being in the ratio 2 to 3, of 3 to 4, or of 4 to 

 5, he infers that these oxides contain also this number 

 of molecules; for otherwise (granting always the hy- 

 pothesis of molecules) one of them would contain a 

 fraction of a molecule, which is not admissible. Com- 

 bining (6) any oxide with another oxide, which may 

 serve as a (saline) base to it, or which, in respect of it, 

 is electro. negative, most frequently it happens that 

 the oxygen contained in the electro negative oxide is a 

 multiple by 2, 3, 4, &c. of the oxygen contained in the 

 electro-positive oxide. It follows next that the number 

 must be such as to introduce no fraction of a molecule 

 into the electro-negative oxide. An oxide of A, for 

 example, which contains 3 molecules of oxygen, 

 if it be combined with another B, so that A contained 

 4 times as much oxygen as B, would always presup- 

 pose a fraction of a molecule to exist in the radical of 

 A. But, in examining the combinations of oxides with 

 each other, in their different degrees of mutual satura- 

 tion, Berzelius has lately found that both the cir- 

 cumstances (a and b) lead always to the same result ; 

 and that, from their coincidence, the number of mole- 



Propor- 

 tions, 



Determi 

 nate. 



