138 



ELECTRICAL CONDUCTIVITIES, ETC. 



and a large number of its derivatives were investigated. The following table gives 

 the results for two volumes and three temperatures for all of these substances: 



Acid. 







v = S2 y = 1024 



Malonic 43 . 51 



Dimethylrnalonic 32.00 



Ethylmalonic. 40.90 



Diethylmalonic 92 . 77 



Methylethylmalonic ] 45 . 89 



Isopropylmalonic 40 . 07 



Dipropylmalonic 103 . 1G 



Butylmalonic I 37 . 53 



Benzylmalonic 45 . 06 



Allylmalonic 45 . 62 



153.3 



124.1 



146.45 



201.22 



156.21 



144.1 



203.51 



140.0 



153.05 



158.93 



25 



v = 32 y = 1024 



72.23 

 51.23 

 64.42 



138.84 

 72.45 

 64.92 



154.54 

 58.72 

 69.82 

 71.47 



251.2 



198.93 



231.24 



311.98 



248.19 



234.00 



317.78 



218.3 



239.44 



248.67 



65 c 



v = 32 i' = 1024 



77.1 



90.66 



186.22 



104.35 



91.73 



83'93 



97.76 



101.16 



299.26 



330.62 



462.78 



365.54 



343.8 



468.0 



320.1 



345.35 



358.28 



The presence of two methyl groups weakens the acid, while two ethyl groups more 

 than double the strength. Ethyl, methylethyl, isopropyl, butyl, benzyl, and allyl 

 affect the conductivity very slightly. Dipropyl more than doubles the strength of 

 the acid. These empirical relations have a certain kind of interest, but their mean- 

 ing is at present not at all fully understood. 



Succinic acid at zero and ?; = 32 has a conductivity of 9.21, being much less than 

 malonic. This is in accord with the relation pointed out between the strengths of acids 

 and their position in an homologous series. Monobromsuccinic acid was studied 

 at v= 128. It had a conductivity of 101.46 against succinic at this volume of 18.24, 

 showing that bromine increases acidit}^. Dibromsuccinic at volume 128 and has 

 the conductivity 254.34, showing the effect on acidity of the second bromine atom 



Pyrotartaric at z- = 32 has n v = 10.94, n v for a-tartaric at v = 32 = 34.18 and for 

 racemic = 34.60. These two isomeric acids have practically the same conductivity. 



The kind of isomerism, illustrated by maleic and fumaric acids stereoisomerism, 

 is interesting in the present connection. We have seen that ordinary isomeric acids, 

 using that term as we generally do, have very nearly the same conductivity. Maleic 

 and fumaric acids at the same volumes and temperatures have widely different con- 

 ductivities. Thus at v = 32 and 0, fx for maleic acid = 108.1, n v for fumaric = 35.46. 

 The results for itaconic, citraconic, and mesaconic acids differ widely. For y = 32: 



fi t for itaconic = 13.50 n v for citraconic = 68.66 p t for mesaconic = 33.31 



Passing to the acids of the aromatic compounds, the introduction of chlorine into 

 benzoic acid raises the conductivity at r = 64 and from 18.49 to 85.20. m for 

 orthonitrobenzoic at t' = 128 (0) is 146.9, for metanitrobenzoic = 40.1. This shows 

 the effect of chlorine and of the nitro group in the ortho position on the acidity. 

 The 1, 2, 4 dinitrobenzoic at and r = 32, /z= 166.51, showing that the second nitro 

 group in these positions still further increases the acidity. The 1, 3, 5 dinitrobenzoic 

 at r = 512 has a value for /x r of only 122.28. 



The effect of the nitro group in increasing acidity is well illustrated by picric acid. 

 Phenol is a very weak acid, one of the weakest, while trinitrophenol is very strong. 

 Its dissociation is of the same order of magnitude as the strongest mineral acids. 



The effect of the introduction of the hydroxyl group into benzoic acid, on the 



