<>XY<JKN AND ITS sALINK COMBINATIONS 199 



Inasmuch as oxygen compounds predominate in nature, it should 

 be expected, from what has been said above, that the occurrence of 

 salts, rather than of acids or bases, would be most frequent in nature, 

 for the latter on meeting, especially under the medium of the all-per- 



by metals that is, it is the hydrogen of an acid). Baume disputed Rouelle's opinion 

 concerning tin- subdivision of salts, contending that normal salts only are true salts, ami 

 that basic salts are simple mixtures of normal salts with bases and acid salts with acids, 

 considering that washing alone could remove the base or acid from them. Rouelle, in tin- 

 middle of the last century, however, rendered a great service to the study of salts and 

 the diffusion of knowledge respecting this class of compounds in his attractive lectures. 

 He, like the majority of the chemists of that period, did not employ the balance in his 

 researches, but satisfied himself with purely qualitative data. The first quantitative 

 researches on salts were carried on by Wenzel about this time. He was the director of 

 the Freiburg mines, in Saxony. Wenzel studied the double decomposition of salts, and 

 he observed that in the double decomposition of neutral salts a neutral salt was always 

 obtained. He proved, by a method of weighing, that this is due to the fact that the satura- 

 tion of a given quantity of a base requires such relative quantities of different acids as are 

 capable of saturating every other base. Having taken two neutral salts for example, 

 sodium sulphate and calcium nitrate let us mix their solutions together. Double 

 decomposition takes place, because the almost insoluble calcium sulphate is formed. 

 However much we might add of each of the salts, the neutral reaction will still be pre- 

 served, consequently the neutral character of the salts is not destroyed by the inter- 

 change of metals ; that is to say, that quantity of sulphuric acid which saturated the 

 sodium is sufficient for the saturation of the calcium, and that amount of nitric acid 

 which saturated the calcium is enough to saturate the sodium contained in combination 

 with sulphuric acid in sodium sulphate. Wenzel was even convinced that matter does 

 not disappear in nature, and on this principle he corrects, in his Doctrine of Affinity, 

 the results of his experiments when he remarked that he obtained less than he had origi- 

 nally taken. Although Wenzel deduced the law of the double decomposition of salts 

 quite correctly, he did not determine those quantities in which acids and bases act on 

 each other. This was done quite at the end of the last century by Richter. He deter- 

 mined the quantities by weight of the bases which saturate acids and of the acids which 

 saturate bases, and he obtained comparatively correct results, although his conclusions 

 were not correct, for he states that the quantity of a base saturating a given acid varies 

 in arithmetical progression, and the quantity of an acid saturating a given base in geo- 

 metrical progression. Richter studied the deposition of metals from their salts by other 

 metals, and observed that the neutral reaction of the solution is not destroyed by this 

 exchange. He also determined the quantities by weight of the metals replacing one 

 another in salts. He showed that copper displaces silver from its salts, and that zinc 

 displaces copper and a whole series of other metals. Those quantities of metals which 

 were capable of replacing one another were termed equivalents. 



Richter's teaching found no followers, because, although he fully believed in the dis- 

 coveries of Lavoisier, yet he still held to the phlogistic reasonings which rendered his 

 expositions very obscure. The works of the Swedish savant Berzelius freed the facts 

 discovered by Wenzel and Richter from the obscurity of former conceptions, and led to 

 their being explained in accordance with Lavoisier's views, and in the sense of the law 

 of multiple proportions which had already been discovered by Dalton. On applying to 

 salts those conclusions which Berzelius arrived at by a whole series of researches of re- 

 markable accuracy, we are obliged to acknowledge the following law of equivalents 

 oni' part by weight of hydrogen in an acid is replaced by the corrcsjHHtditiy i-<jnir<ilriif 

 irr'ujht of any metal ; and, therefore, when metals replace each other their weights are in 

 the same ratio as their equivalents. Thus, for instance, one part by weight of hydrogen 

 is replaced by 28 parts of sodium, 89 parts of potassium, 12 parts of magnesium, 20 parts 

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