Reducing the Results of Experiments. 91 



The properties examined by me were the heat of dissolu- 

 tion, electric conductivity, heat capacity, freezing-point, 

 densities (4 sets of determinations at different temperatures), 

 contraction on mixing and expansion by heat (for 3 different 

 intervals of temperature); and, as I repeatedly insisted, the 

 whole strength of my conclusions rested on the fact that all 

 these different properties, forming figures differing so entirely, 

 as they did, from each other in general appearance (see Phil. 

 Mag. xxix. pp. 430, 431), yet indicated the existence of 

 changes of curvature at the same points. The indications 

 were obtained by examining both the experimental figures, 

 and also the curves representing the rate of change of the 

 properties with change of composition (the direct first differ- 

 ential), with the help of a bent ruler ; totally different methods 

 of plotting, moreover, were adopted, without in any way 

 modifying the conclusions drawn, and these conclusions were 

 further strengthened by the fact that the various sections in 

 which the whole figures have to be drawn all appeared to be 

 curves of a similar nature — parabolas of a certain order — as 

 was proved by their yielding straight lines on further differ- 

 entiation, and also by the fact that these changes, wherever 

 it was possible to draw any conclusion at all on this head, 

 occurred at simple molecular proportions of the acid and 

 water. 



Thus the main feature of the evidence on which I relied 

 was its cumulative character, and this Mr. Lupton seems to 

 have entirely ignored. My determinations numbered 1100 ; 

 of these he has examined 10 : the indications of changes of 

 curvature numbered 102 * ; of these he has examined one, and 

 by disproving this one he thinks he will discredit the whole 

 work. 



This being the character of my work and of the criticism 

 levelled against it, it is rather surprising to find Mr. Lupton 

 opening his remarks with the following sentence : — a In the 

 hurry of modern life experimentalists are apt to omit the test 

 of accuracy afforded by obtaining the same results by several 

 different methods. Thus long rows of figures are frequently 

 given which have in reality no experimental basis to rest 

 upon." 



I scarcely think that I shall be unfair if I accuse Mr. 

 Lupton of attacking my work before he has made himself 

 master of the description of it. He complains of the absence 

 of those very details which he might have found by looking 



* Not, however, at 102 different percentages, as Professor Armstrong 

 imagines (see Chem. Soc. Proc. 1891,. p. 106). 



