274 M. R. Schneider on Equivalents, and 



the correctness of the equivalents, it may certainly be considered 

 as supporting it. 



The assumed equality of the equivalents of cerium and lan- 

 thanium (46), of didymium and molybdenum (48), of platinum 

 and iridium (99), of rhodium and ruthenium (52), of glucinum 

 and lithium (7), will scarcely be considered by any one as an 

 established fact ; most of tliese numbers require further confir- 

 mation. Whether the equivalents of nitrogen and of silicium are 

 to be both put = 14, will depend upon the subsequent solution 

 of the question whether silicic acid has the formula SiO^ or SiO-. 

 Although many arguments support the first view, still the latter 

 caimot as yet be considered as completely disproved. It is cer- 

 tainly corroborative of the latter view, that the number 21, and 

 not 14, stands in a series of regular differences to the equivalent 

 of carbon (6) and that of boron (11), as has been already specially 

 pointed out by Petteukofer *. 



According to the preceding, it appears to me that the assump- 

 tion that different elements have the same equivalent, must be con- 

 sidered, for the present, as unproved. 



Further, according to Dumas there is a certain law according 

 to which some equivalent numbers arc simple multiples of a 

 quarter of the equivalent of hydrogen. Amongst others the 

 equivalent of strontium, 43*75, belongs to this class. I consider 

 it unsafe to speak positively of a quarter of an eqiiivalent of 

 hydrogen, when such high numbers as these are in question ; 

 because even in the hands of M. Dumas, even with much lower 

 equivalents — for instance, that of manganese — vaiiations or 

 errors of one and a half entire hydrogen units are possible. If 

 quarter equivalents be adopted, we should be obliged consistently 

 to admit eiyhtlis of hydrogen equivalents, I consider such a 

 proceeding to be decidedly injurious : it gives those who are ill- 

 informed, and incapable of forming an accurate judgment, false 

 notions concerning the power and capability of our methods ; 

 and it allows important questions to appear decided and solved, 

 which are not so in reality. It is clear that the smaller the unit is 

 which is taken, the more nearly must the experimental numbers 

 coincide with multiples of this unit. Whether and how far they 

 approach the truth, remains still an open question. 



If we reflect how many methods v/hich were formerly consi- 

 dered accurate are now recognized as inacciu-atc, how many sub- 

 stances which Vvcre formerly considered chemically pure, have 

 been shown subsequently to be impure — in relation to how many 

 the views of their constitution have had to be altered, — we cannot 

 avoid entertaining the doubt that many of our equivalent numbers flj 

 are still possibly considerably inaccurate. The experience of the ^P 

 * Aim. der Chem. und Pliarm.. vol. cv. p. 1J>7. 



