August 31, 1883.] 



SCIENCE. 



289 



presented a series from neutral purple to decided 

 red. This formed a scale of colors for reference. 

 Saturated solutions were prepared of the sulphates 

 of Zn, Cu, Pb, Ag, Ca, Na, Hg, 5ln, Al, and Ke, and 

 Zn Clj,. To each of these solutions, enough litmus 

 solution w.as added, in a scries for each salt, to ex.ictly 

 correspond in amount with the sulphuric-acid tubes. 

 As each tube of a dissolved salt was prepared, and 

 also as it was successively diluted with increasing 

 amounts of litmus, it was compared with the tubes 

 in the A)lor-scale, by looking across the two tubes, 

 until its corresponding tint was found. A complete 

 record of these correspondences was made; and it 

 furnished the means for constructing a diagram, in 

 which the results are plotted in curves. 



neutral under all degrees of dilution. 2°. Sulphates 

 of the R. SO, type, where R is a dyad metal, show an 

 amount of dissociation i>r(ipi>rtioned to the degree of 

 ililution. 3°. Aluminic sulphate, and other double 

 triads, are not neutral when concentrated. When 

 diluted they soon become strongly acid. Wlien the 

 dilution exceeds a certain limit, they lose acid at a 

 decreasing rate. 



Suggestions for computing the speed of chemi- 

 cal reactions. 



BT R. B. TVARDKH OF CIXCIXNATI, O. 



Tins paper urges a thorough discussion of data 

 upon the subject indicated in its title, for the follow- 

 ing reasons: 1°. To discover and investigate the 



The following were the chief results :^Ca S04 and 

 Nao So, each continued to act as a neutral salt, with- 

 out effect on the litmus thiougliout the range of dilu- 

 tions. Ag.. SO, was the only salt which changed the 

 solution to a blue. The results with Fe^ (SO,);, and 

 Fe SO, were unsatisfactory because of a dirty pre- 

 cipitate, but both made the litmus red. Zn Cl^ pre- 

 sented a similar difficulty. There is a doubt about 

 the result with ITu St),, and some obscurity about the 

 greatly diluted solutions of Al - (SO,) , and Cu So,. 



On account of instability of cidor, probably caused 

 by oxidation, a fresh color-scale had to be prepared 

 every day, and the mixtures were made under a film 

 of paraffine. 



These experiments seem to indicate that: 1°. Sul- 

 phates of the alkali metals, except silver, are strictly 



causes of certain discrepancies between published 

 observations and current theories. "2°. To obtain 

 more definite information as to the n<iture of certain 

 reactions and the conditions determining their speed. 

 3°. To afford numerical data for a fuller study of 

 relations between the speed of reactions and other 

 physical constants. 4°. To suggest fruitful lines for 

 further research in chemical dynamics. 



As instances of the need of such discussion, the de- 

 terminations by Professor Jlenschutkin, of the speed 

 and limits of the etherilication of the several alcohols 

 and acids, give numbers for the initial speed of reac- 

 tion in one hour which are not proportional to speeds 

 during the first minute. Prof. L. Meyer in his Dyna- 

 mik tier atomen passes very lightly over both the theory 

 and the observations of speed during a reaction. 



