342 KEPOET— 1886. 



That this was no final solution of the problem I knew at once, and said so. And as 

 soon as I had concluded with the stronger solutions at a time when of all other 

 observations only those of Lenz were at hand, I recommenced with strongly dilute 

 solutions. The specific diihculties of these expe-riments, the striving after accuracy and 

 desiring to give absolute values, retarded the conclusion. But all my doubts, e.g., 

 as to whether sulphuric acid in great dilution did not conduct exactly like the 

 monobasic mineral acids, were perfectly removed before auy publication on the 

 subject. 



These remarks are only caused by the wish that a research to which I have 

 given years may not be regarded finally as a mere repetition of someone else's work. 

 Sly repulsion against publishing observations which I considered were open to im- 

 provement, was tlie cause of other investigators' earlier publications, they thereby 

 gaining in many things the publisher's priority. On the other hand I can consider 

 my research as of a greater experimental precision, and that you expressly recog- 

 nise this for the later publication perfectly satisfies me. 



M. Bouty reiterates his objections to my method of measuring resistances with 

 alternating currents.' The empiric ground of this objection has been referred by 

 me, and by you also, to an erroneous formula which M. Bouty used. The 

 difficulties which Messrs. Bouty and Foussereau yet find will surely be overcome if 

 these gentlemen will go through the same experiments which I ' at some length ' 

 described in my last treatise. M. Bouty "s regret, that the water for solutions 

 could not be obtained absolutely pure, must, of course, remain ; but the same diffi- 

 culty occurs in all observations of others addressed to the same object, and in most 

 of them to a much higher degree than in mine. If the water which / used for 

 solutions does not suffice for the explanation of the phenomena of dilute solutions, 

 then this explanation is so tar entirely unknown. I am also in this case obliged to 

 you that you have emphasised my carefulness in this direction. M. Bouty says : 

 ' Let us admit this conductivity as accurately known.' I measured the conductivity 

 of the water every time shortly before the series of observations ; those observations 

 in which the characteristics of the solvent came into account at all were then 

 made within a quai-ter of an hour. The telephonic method of measurement is so 

 specially valuable on account of its very rapidity. That the conductivity of the 

 solvent water must be subtracted from the conductivity of the solution, I have (for 

 neutral salts) shown as proba))!}' ^ery nearly correct. At present also I do not 

 know how an observer could do otherwise. Finally, even an inaccuracy from this 

 cause could only affect the most dilute of my solutions noticeably ; considering 

 the degree of dilution with which the other memoirs have to do, I cannot at all 

 allow a possible inaccuracy proceeding from water in my observations. 



Of course 31. Bouty is correct in considering the use of quite pure (non-con- 

 ducting) water as necessarj^, in order to explain with perfectly conclusive proof 

 the relations obtaining in extreme dilutions. To consider his 'law of eqidvalents ' 

 thus far as an a.viom cannot be denied him. Experience, however, in all observa- 

 tions (his own among them) disagrees with it, and I cannot see the necessity nor 

 the probability of this axiom. It is indeed remarkable that the great differences of 

 conductivity of strong solutions in the case of all salts reduce to about 30 per 

 cent. Grotrian and I twelve years ago found this law, which is true for salts of 

 monovalent acids even in moderate dilution, for the chlorides of the light metals. 

 Lenz proved the same thing in a more general form, making use of more extreme 

 dilutions. It is to the credit of Bouty that he set aside the yet remaining excep- 

 tions. It would certainly be heartily welcomed by every physicist if finally the 

 equality of all molecular conductivities in extreme dilution should be proved. With 

 Arrhenius one could then place this law alongside of the Boyle-Maniotte's law. I 

 myself, since I first introduced the conception of the ' molecular conductivity,' 

 would have an especial motive in agreeing to such a striking meaning of this 

 conception. At times, however (as you yourself mention) the law, at common 

 temperatures, does not agree with known facts. 



Eight years ago I announced the following relation : — ' The better a substance 



> pp. 339, 354, 356, 384. 



