PROPORTIONS DETERMINATE. 



185 



Proper- Some exceptions to this rule were at first considered 

 tlon, by him as proceeding from our inadequate acquaint- 

 ance with the number of molecules in such bodies; 

 but after a more compreheiftive examination, he is of 

 opinion, that there exist combinations of two molecules 

 of ore element, with three of another ; which, however, 

 he inclines to believe do not occur between two ele- 

 ments alone, but require the presu-nr- of a third 

 feet their union. Thus the subsulphate of oxide of 

 copper is composed of .'{ (.'u. -f 2 .S, whilst no combin- 

 ation of 3 Cit. -f- 2 S, is known to exist, or can exist, 

 as Berzelius thinks ; because nothing more than a force 

 purely mechanical seems requisite to divide it into one 

 molecule of 5 -f- C, and one of S + 2 C. A jn ioi i, 

 it cannot be decided whether, in the compass of inor- 

 ganic nature, molecules do not combine in still more 

 complicated numbers ; such as 3 A -f 4 B, 3 A -f- 5 li, 

 ftc. &c. ; but so far as actual experience allows us to 

 decide, it is reasonable to suppose that no such com- 

 binations occur. On attempting to discover the cense 

 why the molecules, in all inorganic substances, com- 

 bine only according to proportions so limited, we ar- 

 rive at certain boundaries, over which it is not per- 

 mitted for the present to extend the empire of science. 

 We cannot explain how it happens, that if oxygen be 

 added to a solution, say of Fe "& (= the subsulphate 

 of the protoxide of iron,) there results not an Fe *V 2 , 

 but a division of the compound into Fe A' 3 and Ft 1 A'. 

 The phenomenon naturally depends no less on the 

 forces which cause the elements to combine, than on 

 the change of form produced upon the new molecules 

 created by the addition of oxygen ; and so long as we 

 remain ignorant of the greater part of what concerns 

 these two circumstances, we shall be obliged to con- 

 tent ourselves with simply knowing the facts. It is 

 alike blamable not to speculate at all about the causes 

 of phenomena, and to push the speculation to a length, 

 where, no longer being guided by experiment, it be- 

 comes altogether fictitious and imaginary. 



At the ">ide of this corpuscular theory, M. Berzelius 

 has placed another, that of volumes. As experiment 

 proves that almost all bodies are capable of being vo- 

 latilized in temperatures sufficiently elevated, it is al- 

 lowable to conceive all bodies as existing under the 

 gaseous form, in which they must of course obey the 

 laws, discovered by M. Gay Lussac, concerning the 

 volumes of gases in a state of combination. Regarding 

 water as compounded of two molecules of hydrogen to 

 one of oxygen, it follows that the weight of a volume 

 of an elementary substance is equal to the weight of a 

 molecule of the same substance. And hence the only 

 difference between these two hypotheses lies in the cir- 

 cumstance, that the one views bodies in the solid, the 

 other in the gaseous state. The latter is founded en- 

 tirely on facts ; it is therefore less hypothetical than 

 that of molecules, and serves better to direct our re- 

 searches concerning chemical proportions. But, after 

 all, when one attempts to form an idea of what a gas 

 is, and of the state in which the solid particles, gasified 

 by heat, really exist in such a substance, the specula- 

 tion always reverts to molecules, and shows that both 

 hypotheses are substantially the same, their difference 

 consisting solely in the words atom and volume. 



What has now been laid down with regard to the 

 state of combination among molecules, is applicable 

 only to inorganic nature. The case is widely different 

 in the kingdoms of organic nature, where the great 



VOL. XVII. FAtfT I. 



cries of analogous bodies display modes of combina- 

 tion much more numerous, we might almost say, innu- 

 merable. In proof of this, we have only to consider 

 the long list of essential oils, for example, in which the 

 difference of specific gravity, traell, &c. prove that they 

 cannot have the same composition ; whiUt, on the 

 other hand, tht-ir general chemical character* prove 

 that the di Hen-nee in their composition mufct be very 

 inconsiderable. How can this be reconciled with what 

 we have just stated concerning inorganic nature ? 



AI. Herzcliu.s extended hit experiments also to this 

 very difficult and delicate point ; to see if k were po- 

 sible to find the general differences among the laws, 

 according to which these two different departments of 

 nature have been formed. He analyzed the following 

 vepc table substances : oxalic, acetic, succinic, formic, 

 tartaric, citric, faccolactic, henzoic, and gallic acids ; 

 tannin, mgar, sugar of milk, gum, and starch. Al- 

 though this is rot the place for giving an account of 

 the analytic method employed in those experiment*, 

 it may not be altogether useless to devote a few word* 

 to that point. He combined the substance to be ana- 

 lyzed with oxide of lead, and deprived this combina- 

 tion of all its water, and afterwards analyzed it to dis- 

 cover the exact quantity of oxide of lead and of vege- 

 table matter contained in it. A quantity of this sub- 

 stance, correctly weighed, was then burnt with supcr- 

 oxygenated muriate and oxymuriate of potass, in an 

 apparatus contrived for the purpose. The water and 

 carbonic acid extracted from it, indicated the quantity 

 of hydrogen and carbon. The loss was the oxygen of 

 the substance. On analyzing the fourteen substances 

 above mentioned, he always found the oxygen of the 

 substance to be an integer multiple of that contained 

 by the oxide of lead, with which it had been combin- 

 ed ; so that organic substances appear to obey the 

 same law as inorganic oxides. Now, according to the 

 reasons already explained, the number by which tke 

 oxygen of the analyzed substance is a multiple of the 

 oxygen contained in the oxide of lead combined with 

 it, must either be the number of molecules of oxygen 

 in the analyzed substance, or else it must be an integer 

 divisor of the number of those molecules. But, if it is 

 allowable to conceive substances as compounded of 

 atoms or molecules, the resulting weights of hydrogen 

 and of carbon must al.-o be those of some number of 

 entire molecules belonging to these two elements. 

 Acetic acid, for example, is composed of 46.934- parts 

 of oxygen, 46.871 parts of carbon, and 6.195 parts of 

 hydrogen. The quantity of oxide of lead neutralized 

 by this quantity of acetic acid, contains 15.645 parts of 

 oxygen, and 15.645 X 3 := 46-934 ; but, if this quan- 

 tity of oxygen forms S molecules, 46.871 will form 4 

 molecules of carbon, and 6.195 will form 6 of hydro- 

 gen. So that each molecule of acetic acid is composed 

 of 6 H -f- 4 C -f- 3 O. The following is a summary of 

 the analytical results obtained by fit. Berzelius from 

 analyzing the fourteen substances in question. 



J' r- 



J A 



