August i6, 1906] 



NA TURE 



40; 



societie:- axd academies. 



I.ONIH.N. 



Royal Society, .May 31.— "The MVmily Constants of 

 Ar.photeric Elcclrolvtos." I. " Methyl Deriwitivos ol 

 [Viia-amiiio-benzoic .Acid and of Glycine," by John John- 

 ston. II. " Methvl Derivatives of Ortho- and Meta- 

 amlno-benzoic Acids," by A. C. CumminK. III." Methyl- 

 ated Amino-acids," bv James Walker. 



The object of the present scries of papers was to deter- 

 mine the influence of the substitution of the methyl group 

 in NH„ on the acidic and basic dissociation constants of 

 amino-acids. The methods employed for the determin- 

 ation of the dissociation constants were for the most part 

 hydrolytic, i.e. the degree of hydrolysis in aqueous solu- 

 tion of both tvpes of salts 'of the amino-acids was 

 estimated at given dilutions. For the basic constant 

 methvl acetate catalvsis, Lowenherz's solubility method 

 and ' Farmer and Warth's distribution method werr 

 employed. In addition to these methods, the delicate 

 diazo-acetic ester catalysis of Bredig and Fraenkcl was 

 used in a few instances. For the acidic constant, the 

 electrical conductivity and Shields's saponification method 

 were utilised. 



Each substance investigated was subjected to careful 

 purification, and many new methods were devised for the 

 preparation of the methyl derivatives required. It may be 

 noted that the monomethvl-meta-amino-benzoic acid de- 

 scribed by Griess is a mi.Kture of the monomethyl and 

 dimethyl derivatives which it is practically impossible to 

 separate by recrystallisation. 



.\ comparison of the acidic and basic constants of the 

 various substances examined showed that they were in 

 general accordance with the following scheme. The 

 primarv influence of the substitution of methyl for hydrogen 

 in the amino group is to raise the basic and diminish the 

 acidic constant, the effect in both cases being, however, 

 onlv slight. This primary influence is usually obscured by 

 greater secondary influences due to stereochemical changes. 

 These changes may exert their influence (1) by mere 

 approximation of the active groups ; (2) by change in degree 

 of hydration of the basic group; (3) by ring-formation. 

 In the case of ring-formation the acidic constant is 

 diminished, speaking in general terms, proportionally to 

 the extent to which the ring-formation has taken place. 

 The basic constant, on the other hand, need not be so 

 diminished, because the basic constant in the bodies investi- 

 gated is principally a function of the hydration constant 

 of the basic group, and the degree of hydration may not 

 he diminished by increased ring-formation. A comparison 

 of the basic constants of the amino-acids with those of 

 their methyl esters affords information regarding the 

 reciprocal stereochemical influence of the active groups. 

 When there is little stereochemical influence the basic 

 constant of the acid is nearly equal to that of the ester. 

 \^'hen the stereochemical influence is marked the basic 

 constant of the acid is much less than that of the ester. 

 The following table of the constants of ortho-amino- 

 benzoic acid and of para-amlno-benzoic acid and their 

 methyl derivatives may serve as illustralions. In the ortho 

 series stereochemical influences are apparent, in the para 

 series they are nearly absent. 



Ortho Scries. 



t., ■■ 10' H/, 



2-5 



'-'5 very great 



The great drop in the acidic constant of dimethyl-ortho- 

 benzoic acid is due to ring-formation. In the case of the 

 betaines the ring-formation must be nearly complete, as 

 the acid constant has practically vanished. The basic 

 constant of the betaines still assumes a comparatively high 



NO. 1920, VOL. 74.] 



value, notwithstanding the extensive ring-formation, owing 

 to the very high constant of the quaternary basic group, 

 which cannot suffer dehydration except through ring- 

 formation. The quaternary basic group of the betaine 

 esters was proved to have basic properties comparable in 

 strength with those of the caustic alkalies. 



June 21. — " On the Distribution of Radium in the 

 Earth's Crust." By the Hon. R. J. Strutt, F.R.S. 



In a paper read before the society on April 5, the author 

 gave determinations of the quantity of radium in igneous 

 rocks. Similar data for sedimentary deposits will now be 

 given to complete the survey of the radium content of the 

 earth's crust. • -r 1 1 t 



The results for sedimentary rocks are given m Table 1. 



T.ABLE I. 



Oolite 



Oolite 



Marble 



Rimnncridge clay .. 

 Oil-beaiing sandstone 



Koofing slate 



Silicified gtitly slate 



(lault clay 



Clay 



Red sand.'.tone 

 Gravel (fine sifiingsi 



Red chalk 



Flint (large nodulesi 

 White marble .. 



Marble 



Chalk 



Chalk' 



On comparing these figures with those given in the 

 former paper for igneous rocks (Roy. Soc. Proc, vol. 

 Ixxvii., A, p. 479, last column but one of the table), it will 

 be observed that the average radium content of sedimentary 

 deposits does not differ appreciably from that of igneous 

 rocks. This is what might be expected on the received 

 view that sedimentary rocks derive their material from 

 the disintegration of igneous ones. 



The author has examined a number of specimens of 

 rock-forming minerals for radium. The results are given 

 in Table II. In some cases the quantity of material taken 

 Table II. 



grams of material, in order to 



