January 31, 1896.] 



SCIENCE. 



Ill 



to a discussion of tlie experimental data which 

 have a bearing upon Nernst's theory of the E. 

 M. F. of a voltaic cell. Dr. Bancroft is in- 

 clined to look upon certain aspects of this the- 

 ory with considerable distrust. His conclusions 

 may be summed up as follows: 



1. The potential difference between a metal 

 and an electrolyte is not a function of the con- 

 centration of the salt solution, nor of the nature 

 of the positive ion, except in certain special 

 cases. 



2. It is a function of the electrode, of the 

 negative ion, and of the solvent. 



3. In aqueous solutions the potential differ- 

 ence is the sum of the term due to the electrode 

 and the term due to the negative ion in the 

 normal cases. 



4. For most metals in most electrolytes the 

 term due to the negative ion has the same 

 numerical value and the same sign. 



The tables accompanying this article, in 

 which are collected the results of some ten dif- 

 ferent observers, will be found of especial value. 



On the Freezing Points of Dilute Aqueous So- 

 lutions: By E. H. LOOMIS. The phenomenon 

 of the lowering of the freezing point of a liquid 

 by the presence of a dissolved salt has so im- 

 portant a bearing upon the theory of solutions 

 that innumerable experimenters have made it a 

 subject of study. That such determinations are 

 extremely liable to serious error is shown by 

 the disagreement between the results of dif- 

 ferent observers. In some previous work on 

 this subject Dr. Loomiswas led to make several 

 improvements in methods and apparatus. The 

 present paper gives the resu'ts of his new 

 methods in the case of certain electrolytes, the 

 salts studied being principally chlorides, car- 

 T)onates and nitrates. In general the results 

 may be said to be in fair agreement with the 

 theory of electrolytic dissociation. With KCl 

 and KjSOj the agreement is complete. With 

 half a dozen other salts it is not so good, but 

 fairly satisfactory. K^COj and Na^COj show 

 considerable discrepancies, which, however, 

 may be due to uncertainty in the determination 

 of the conductivities of these salts. 



Dr. Loomis devotes considerable time to a 

 discussion of the probable accuracy of his re- 

 sults, and in a minor article in the same num- 



ber of the Review answers certain objections 

 which have been raised against his earlier de- 

 terminations. 



A Comparison of two Concave Rowland Cfratings : 

 By Alice H. Brueee. Miss Bruere subjects 

 'the well-known irregularities in the intensity 

 of the difFereut spectra from a concave grating 

 to a careful photometric study. The results 

 show the same general character as those reached 

 by Paschen by bolometric methods. The curves 

 which accompany Miss Bruere' s article show in 

 a most striking manner the irregularities in in- 

 tensity in different parts of the same spectrum, 

 as well as in the spectra of different orders. 



A New Apparatus for the Study of Color Phe- 

 nomena: By E. R. VON Nardeoff. Mr. von 

 Nardroff describes an ingenious apparatus to be 

 used with a lantern for conveniently showing 

 the various experiments dealing with color 

 mixing, contrast, complementary colors, etc. 

 The apparatus has been used by Mr. von Nar- 

 droff for several years and found satisfactory 

 and convenient. 



On a New Form of Water Battery : By L. W. 

 Austin and C. B. Thwing. The writers have 

 devised a cell which is constructed out of a 

 homeopathic vial and strips of sheet copper and 

 zinc, and which appears to possess considerable 

 advantages. The chief novelty consists in the 

 form of the two electrodes. Ease of consti-uc- 

 tion, convenience in filling, and permanence of 

 action are the advantages urged. 



Books Reviewed : Daniell, Principles of Phys- 

 ics ; Whetham, Solution and Electrolysis ; S. 

 P. Thompson, Polyphaze Currents; Palaz, In- 

 dustrial Photometry; Walter, Oberflachenf^r- 

 ben ; Gierke, The Herschels and Modern As- 

 tronomy. 



SOCIETIES AND ACADEMIES. 

 joint commission of the scientific societies 

 of washington. 

 The memorial meeting held by the Scientific 

 Societies of Washington, on Wednesday even- 

 ing, January 14th, at which addresses were 

 made in honor of Dana, Pasteur, von Helmholtz 

 and Huxley, was followed on the following even- 

 ing, the 15th, by a meeting of the Joint Com- 

 mission, in honor of the late Charles V. Riley, 

 the entomologist. The memorial address by 



