354 EEPORT— 1888. 



portion of the original charge of the atom be still unneutralised ? ' According to 

 this passage I cannot understand Professor Armstrong to mean otherwise than 

 that the molecules will be directed by the electromotive forces, and consequently 

 themselves move along the lines of flow. This way of viewing the question would 

 lead one to expect the molecules to sepai'ate at the electrodes ; but it is found 

 experimentally that not molecules but ions are transported to the electrodes. 



9. Professor Armstrong tinds it difficult to explain why phenylpropiolic acid 

 CgHj.C=C.CO.,H conducts better — i.e., is more dissociated, than hydrocinnamic 

 acid, CgHj.CHj - CH.,.CO.,II. But there are other peculiarities, which, perhaps, 

 are very nearly connected with this circumstance, viz., the physical properties 

 (heat of combustion, refraction of light), which indicate that the triple union in 

 CyHj.C=C.COJI is less firm than the simple union in CyH^.CHj-CH^.CO.^H, 



10. The formula proposed by Professor Armstrong — 



C = E/K, 



* being the amount of change, E the intensity of the total chemical effect,' and 

 E. the resistance of the solution in which the interaction takes place, is not verified 

 by experience. Thus, in the case of the hydrolysis of ethylic acetate by means of 

 bases, ' the intensity of the total chemical efiect ' (E) must be but very little influenced 

 by the presence of neutral salts ; E, on the contrary, very much. But experience 

 shows that 'the amount of change' (the velocity of interaction C) alters but very 

 little (for strong bases) if R be increased by addition of neutral salt from 1 to 

 about 20. In the case of ammonia C decreases extremely rapidly, when IJ, 

 decreases in consequence of added neutral salt. These phenomena are easily ex- 

 plained by the electrolytic dissociation hypothesis, the velocity of interaction being 

 proportional to the quantity of OH in the form of ion. 



The arguments brought forward by Mr. Crompton on the conductivity of 

 sulphuric acid seem to me not very convincing in favour of the view that hydration 

 of H.iSO^ should condition the electrolytic conductivity.' There is no reason 

 mentioned why the second derivative d'kldp- (where /c is conductivity and p con- 

 centration of the acid in per cents.) should have angular points at the places men- 

 tioned ; on the contrary, the author says that he had expected to find such angular 

 points in the dkjdp curve, but when he did not find them there he proceeded to the 

 examination of d'-kjdp-. The author does not take heed of the errors of experi- 

 ment ; a search would probably have shown that these errors in many cases are of 

 the same magnitude as d'kjdp- itself.- Further, the author does not find the same 

 hydrates as Mendelejeff (II,S04 + 24 HoO not appearing in Mendeleiefl''s curve, 

 lioSO^ + 6H.,0 not being marked by Crompton's curve). The part of Crompton's 

 curve between HoSO^ and HoSO^ + 2H.p can hardly be considered as consisting of 

 two straight lines, as the author asserts. The artificial nature of the proposed 

 formulae is manifested by^the circumstance that they give very diflferent values of k 

 at the limiting points where two formulas should be applicable. Moreover, there 

 is a very important difference between the views of Mendelejeff and of Crompton. 

 Mendelejeft' says, ' Ich babe schon lange die schwachen Losungen als die inte- 

 ressantesten angeseheu und dieselben dem zerstreuten oder verteilten Zustande der 

 Materie in Dampfform an die Seite gestellt. Die bemerkenswerten Untersuchungen 

 von van 't Hoff haben gegenwiirtig dafiir emen vollstandigen Beweis erbracht,' 

 whereas, according to Mr. Crompton, dilute solutions are characterised by their 

 irregularities. 



The above observations will, I believe, suffice to show that the objections 



' In saying this I wish not to deny that some (but very few) hydrates (e.ff., 

 H2SO4 + HjO, as Kohlrausch has stated) exert an influence on the conductivity, but 

 only to say that the assertions of Mr. Crompton are to a very high degree ex- 

 aggerated. 



2 Being fully conscious that existing data are insufficient for the complete discus- 

 sion of the problem, Mr. Crompton is engaged in determining the change in conduc- 

 tivity with concentration of a number of solutions ; and with the object of discrimi- 

 nating between errors of experiment and true changes in direction of the curves he 

 is paying particular attention to the influence of temperature (H. E. A.). 



