474 Scientific Intelligence. 



SCIENTIFIC INTELLIGENCE 



I Chemistry and Physics. 



1. The Heats of Neutralization of Potassium, Sodium and 

 Lithium Hydroxides with Hydrochloric, Hydrooromic, Hydrio- 

 dic and Nitric Acids, at Various Dilutions. — Theodore W. Rich- 

 ards and Allan W. Rowe have made a very elaborate study of 

 the heats of neutralization of each of these bases with each of the 

 acids ; the adiabatic calorimeter, which was devised in Professor 

 Richards' laboratory was employed, while the refinements in the 

 precautions employed to secure the greatest accuracy and the 

 remarkable agreements obtained in the various series of deter- 

 minations command the highest praise. The authors had pre- 

 viously determined with great care the heats of dilution of solu- 

 tions of these bases and acids as well as of their salts, in order 

 that the heats of neutralization at various concentrations might 

 be calculated. 



Solutions of uniform molecular concentration, corresponding 

 to a dilution with 100 molecules of water, of the four acids and 

 the three bases were neutralized calorimetrically in all possible 

 pairs at two temperatures not far apart, and the results were 

 interpolated to exactly 20°. The values ranged from 13,750 to 

 14,085 calories, sodium hydroxide giving the lowest values among 

 the bases, and hydriodic acid among the acids. By means of cal- 

 culations to other dilutions, and extrapolations to infinite dilu- 

 tion, it was concluded that the heat of formation of water from 

 its ions at 20° is probably not over 13.69 Cal. (20°) or 57.22 kilo- 

 joules, and possibly not under 13.62 Cal. or 56.93 kilojoules. 



h. l. w. 



2. A Rapid Iodometric Estimation of Copper and Iron in 

 Mixtures of their Salts. — Ian William "Wark has worked out a 

 method for making these determinations successively in a single 

 solution. The process appears to be fairly accurate and very 

 convenient, so that it should find extensive application, particu- 

 larly in technical work. The solution, in which the iron should 

 be in the ferric condition and which should be as concentrated as 

 possible, is neutralized with ammonia. Moderate amounts of 

 ammonium salts do not seriously affect the end-point. Then 2 g. 

 of disodium phosphate, or twice as much if there is little copper, 

 are added for each 0.1 g. of iron, together with 5 g. of KI and 

 5 cc. of acetic acid (80%) for each 0.1 g. of total metal present. 

 The titration with tenth normal thiosulphate for copper is then 

 made after waiting for 5 or 10 minutes, and the mixture is 

 warmed to 50° and titrated further, if necessary, after 5 min- 

 utes. This method for the determination of copper in the pres- 

 ence of iron was described in its essential features by Moser in 



