NOVEMBEE 30, 1900.] 



'SCIENCE. 



825 



tacea it must be placed in the Scaphellidse. 

 The chief distinctive characters of this 

 family, beside the conditions of the larval 

 shell and the absence of an operculum, ap- 

 pear, from Woodward's researches, to be 

 the extreme condensation of the chief gan- 

 glia around the gullet, the development of 

 a very large oesophageal csecum (which led 

 Poiret to suppose Halia had a double 

 oesophagus), and two pairs of preneural 

 salivary glands. If the family is divided 

 into two subfamilies on the basis of the 

 radula, Volutomitrinse with a unicuspid 

 median tooth, will include Amoria, Voluto- 

 mitra and Halia ; while Scaphellinse with a 

 tricuspid tooth will include the others. 

 The typical Voluta and Lyria have wide 

 rhachidian teeth with many cusps, an oper- 

 culum, shelly protoconch, and other char- 

 acters which separate them entirely from 

 the Scaphellidse. According to our present 

 knowledge one of the most important results 

 of Mr. Woodward's labors is to show that the 

 old family of Volutidae included many di- 

 verse types, and that a great deal remains 

 to be done before we can proceed to gener- 

 alize with safety on those of which the ne- 

 pionic stages and anatomy are unknown. 

 Wm. H. Dall. 



RICHTER AND THE PERIODIC SYSTEM* 

 A VERY remarkable work appeared at 

 the close of the last century. This was 

 'Die Anfangs-griinde der Stochyometrie, ' 

 by J. B. Richter, the first volume of which 

 appeared in 1792, and the third and last 

 volume in 1794. In this book we have the 

 first definite statement of the law of pro- 

 portionality, and some have thought that 

 they have found in it also the Atomic 

 Theory, though it was not claimed that 

 this theory was definitely stated. 



Eichter's work attracted attention at the 

 time because of his defense in it of the 



* Read before N. C. Section, Amer. Chem. Soo., 

 Nov. 9, 1900. 



phlogistic theory and it was vigorously at- 

 tacked by the supporters of the New Chem- 

 istry ,who followed Lavoisier and the French 

 chemists. The deeper purport of the book 

 and the new ideas advanced do not seem to 

 have been well understood or to have been 

 largely commented upon. Fischer, who in 

 1802 translated into German Berthollet's 

 ' Statique Chimique,' was apparently the 

 first to draw general attention to the work 

 of Eichter and to its bearing upon the con- 

 clusions drawn by Berthollet. This latter 

 chemist and Guyton de Morveau acknowl- 

 edged that Richter had anticipated them in 

 the inference to be drawn from the per- 

 manence of neutrality after the decompo- 

 sition of certain neutral salts and the 

 possibility of calculating beforehand the 

 composition of the salts produced. The 

 discovery of the law of proportionality 

 was a most important one and Eichter 

 must, therefore, be regarded as a very re- 

 markable man. In his discovery that the 

 amounts of dififerent metals combining with 

 a given weight of acid combine with a 

 fixed amount of oxygen, he went a step 

 further, anticipating the work of Gay Lus- 

 sac, and when he established the fact that 

 such metals as iron and mercury have the 

 power of combining with oxygen in several 

 proportions, showing different degrees of 

 oxidation, he was several years ahead of 

 Proust and verged upon the discovery of 

 the law of multiple proportions. 



With all his ability to see deeply into the 

 workings of natural phenomena, Eichter 

 was not a clear and logical thinker. Wurtz 

 rightly speaks of him as ' the profound but 

 perplexed author of the great discovery of 

 proportionality.' He was confused by his 

 adherence to the illogical phlogistic theories 

 which were becoming each year more un- 

 tenable. He was further hampered by his 

 determination to give a mathematical foun- 

 dation to the science of chemistry and to 

 express all chemical changes by formulae 



