.173 



PROPORTIONS, DETERMINATE.* 



' 



nuns, 



IK'lermi- 



nate. 



1 Roponrioxs, DETERMINATE, in chemistry arc those 

 invariable and fixed proportions, in which elementary 

 substances combine to form compound bodies, organic 

 as well as inorganic. 



It appears that whenever the idea of bodies compos- 

 ed of simple elements had begun to be formed, it was 

 looked upon as certain, that the same characters and 

 properties, existing in different compounds, indicated 

 the same elements combined in the same proportions. 

 At a remote era, before scientific speculations could be 

 founded on an adequate system of experiments, this 

 opinion is to be found in the writings of philosophers. 

 It even forms part of the doctrines of Pythagoras. 

 And 1'hilo, who has collected, in his Libri sapienliae, 

 the choicest philosophical ideas of his time, says, in 

 cap. xi. V. 22, irstvret, 0f; f*iTg **< gify<a Ken ffTatlu* 

 3<iT*gt: " God made all things by measure, number, 

 and weight." And, judging from his manner of in- 

 troducing this reflection, he takes it for a thing fully 

 decided and generally acknowledged. It may be af- 

 firmed, however, that till our own times, this opinion 

 has continued rather an obscure anticipation among 

 philosophers, than a truth completely admitted and es- 

 tablished by experience in general, or by researches 

 entered into with this particular design. No doubt, 

 the first attempt towards a quantitative analysis is due 

 to a belief in this opinion ; yet this first attempt bears 

 no very ancient date. Though we cannot specify with 

 certainty what chemist was the foremost to find the 

 quantitative composition of any substance by analytical 

 experiments, still it is evident enough, that the art of 

 performing chemical analyses with accuracy did not 

 originate till the latter half of the past century ; and 

 to the perfection of this art it is that we owe the dis- 

 covery of determinate proportions in chemistry. 



Ancient chemists appear to have laid it down as an 

 axiom, that the same elements, united in the same pro- 

 portions, produce always the same compound sub- 

 stance. Wenzel, Bergman, and Richter, are the first 

 chemists in whose writings we discover proof of their 

 having perceived that these proportions have a more 

 general relation to each other. In his academical dis- 

 sertation, printed at Upsal in 1780, and entitled, DC 

 divers a phlngisli qnantitate inmetallis, Bergman exhibits 

 a great number of experiments on the precipitation of 

 metals by each other, and draws from his facts the fol- 

 lowing conclusion : PUogisli mutuas qtiantitatcs prac- 

 cipiUinlis et praecipitandi ponderibus esse inverse propor- 

 tionates ; which, in the language of the antiphlogistic 

 theory, signifies, that to neutralize a given quantity of 

 any acid, each of these metals combines with the same 

 quantity of oxygen. Bergman laboured zealously to 

 acquire information concerning the elective affinities 

 and mutual decompositions of several saline substances. 

 He confirmed the general observation, that salts main- 

 tain their neutrality in this case ; but he does not 

 seem to have had just notions about the latter pheno- 

 menon, which indeed stands in direct opposition to the 

 results deduced by Bergman himself, from his analyti- 

 cal experiments upon the composition of a great num- 

 ber of salts. 



Wenzel, a German chemist, contemporary with 



Bergman, examined this matter more carefully, in 

 a memoir on affinities, ( Leltre von den Verwandl- 

 sclutflcnj printed at Dresden in 1777- He proved by 

 experiments, performed with wonderful exactness, 

 that the reason why two neutral salts, decomposing 

 each other, preserve their neutrality, is that the rela- 

 tive quantities of alkalies or earths which neutralize 

 acids, are the same, whatever be the acid requiring 

 saturation : in other words, that, when for example, 

 the neutral nitrate of lime is decomposed by the neu- 

 tral sulphate of potass, the gypsum and the saltpetre 

 which result from the process are also neutral, because 

 the quantity of potass which saturates a given portion 

 of nitric acid is to the quantity of lime which satu- 

 rates an equal portion of that acid, in the same propor- 

 tion as the potass is to the lime which saturates a 

 given quantity of sulphuric acid ; from which it fol- 

 lows, that the neutrality of the two salts must con- 

 tinue even after their mutual decomposition. The 

 numerical results of Wenzel's experiments are won- 

 derfully accurate, and have generally been confirmed 

 by the more careful analysis of later times. It ap- 

 pears, however, that little attention was given to them 

 at the date of their appearance ; and the sanction of 

 more noted chemists secured a preference for results, 

 not only less exact, but even contradicted by the phe- 

 nomenon which Wenzel had so ingeniously explained. 



M. J. B. Richter, another German chemist, re- j, 

 markable no less for the zeal with which he invest!- tcr. 

 gated chemical proportions, than for the mathemati- 

 cal form, which in his work on chemical stochiome- 

 try he wished to impress on the general face of che- 

 mistry, occupied himself with these researches more 

 than any of his predecessors. Great part of his ideas 

 being erroneous, we shall not speak of them. But he 

 not only confirmed by experiments, the idea of Berg- 

 man, and that of Wenzel, he also gave to them a 

 wider extension. His experiments are described in a 

 periodical work, which he published under the title of 

 Uber die neuen Gegenst'dndc der Chemie; and it was 

 principally in Numbers 7, 8, and 9 of this work, that 

 he developed the matters in question. Yet the labours 

 of Richter were not more successful in attracting no- 

 tice ; a circumstance that may be attributed as much 

 to the inaccuracy of his experiments, in which respect 

 he cannot be compared with Wenzel, as to his pecu- 

 liar style, which affects to hold a middle course be- 

 tween the antiphlogistic and the phlogistic system. It 

 is not, however, very probable that those germs of 

 discovery would have been lost solely for such a rea- 

 son, which at all events applies only to Richter. 

 The cause of this neglect is more general. These 

 researches were completed precisely at the time when 

 the immortal Lavoisier, by discoveries of his own, 

 and by luminous applications of the discoveries of 

 others, was undermining the phlogistic system, daz- 

 zling chemists by the new light which he prepared 

 for them, and rendering his own system the sole ob- 

 ject of their attention. That system presented objects 

 of research, which at the moment promised to be- 

 come of an importance vastly greater and more gene- 

 ral. In vain did Richter publish his mathematico- , 



* The Editor hw been indebted for this valuable article to PROFESSOR BEBZEIICS of Stockholm. . 



