594 



SCIENCE. 



[N. S. Vol. XIV. No. 355. 



The latent heat of transformation for one 

 sample of nickel- steel was found to be 2.783 ; 

 that of another, 13.46 ; which, according to 

 the theory of solutions, should have been 

 15.9— the application of the theory being, 

 however, questionable. The specific heat 

 of nickel-steel is greater in the non-magnetic 

 state than in the magnetic (from 2 to 6 per 

 cent., depending on the temperature interval 

 through which it is obtained). 



Six samples of iron differiog in permea- 

 bility showed that the greater the permea- 

 bility of iron the smaller its specific heat. 

 This supports the view that the difference 

 in permeability is caused by a difference in 

 composition of magnetic and non-magnetic 

 iron. 



21. ' On the Demagnetizing Effect of a 

 Discharge in Iron when Electromagnet- 

 ically CompcD sated ' : Zeno Crook. 



22. ' The Absorption Spectra of Solutions 

 of Potassium Permanganate ' : B. E. Moore, 

 University of Nebraska. 



The absorption spectra of solutions of 

 the following concentrations, .25n, .025n, 

 .0025n, .00025/1 and. 000025?i (n = normal), 

 were studied. 



The observations, though they may need 

 later some slight correction, show that upon 

 dilution the solutions become relatively 

 darker in the blue, i. e., there is a displace- 

 ment of the absorption band toward the 

 blue upon dilution. The phenomenon is ex- 

 plained upon the theory of dissociation. 



23. ' The Absorption and Dispersion of 

 Fuchsin ' : W. B. Cartmel. (By title.) 



24. ' On the Determination of Dispersion 

 by Means of Channeled Spectra with the 

 Concave Grating ' : P. J* Antes. 



25. ' Accidental Double Refraction in 

 Liquids ' : Bruce V. Hill, University of 

 Nebraska. 



In a former paper upon this subject 

 (Phil. Mag. (5), 48, p. 485) the writer 

 gave results of a series of experiments upon 

 gelatinizing solutions which became double 



refracting when subjected to a strain be- 

 tween rotating cylinders. The results in- 

 dicated that we have in such solutions quasi- 

 solids, and that there is a difference between 

 colloid and crystalloid solutions not to be 

 explained upon the assumption of a large 

 molecular weight in the former. 



The present experiments consist of an 

 examination of water solutions of gelatine 

 when subjected to a static strain. They 

 vary in concentration from .1 per cent, to .5 

 per cent, and were too dilute to sustain their 

 own weight. They were accordingly placed 

 in thin- walled brass tubes 42.55 cm. in 

 length and 2.77 cm. in diameter. Glass 

 caps were fastened to the ends of these 

 tubes by slipping short pieces of rubber 

 hose over them. The tubes were strained, 

 so that their cross-sections were elliptical, 

 by means of clamps. The double refraction 

 decreases so rapidly with rise in tempera- 

 ture that at room temperature — about 23° 

 C. — no effect was visible in jellies of the 

 above concentrations. The tubes were 

 then surrounded by ice and the formation 

 of dew upon the glass ends was obviated 

 by slipping over the tube a second one, also 

 having a glass cap and containing a little 

 phosphoric anhydride. The amount of 

 double refraction was measured as before 

 by means of a half-shade polariscope. The 

 seven sets of observations show that when 

 a stress is applied, the strain increases to a 

 certain point beyond which no further 

 strain is produced. Further stress ruptures 

 the solution, and the refraction diminishes 

 or ceases. The amount a solution can be 

 strained without rupturing depends upon 

 the age of the solution. This point was 

 suflQciently studied to show that the diluter 

 jellies required much longer time to reach 

 the point where they would sustain a max- 

 imum strain than the stronger jellies. 

 Along with double refraction, depolariza- 

 tion also appears and then diminishes after 

 standing some time. 



