492 Scientific Intelligence. 



Physique, 5th series xix, p. 472). It was found, 1. The curves 

 which result from the observations indicate that at sunrise there 

 is a predominance of the more refrangible rays. These rays 

 diminish at midday, and augment again at sunset, never attaining 

 during the afternoon hours the values attained during the morn- 

 ing hours. 2. The curves vary from day to day, in regard to 

 the more refrangible rays, with the state of the atmosphere. 

 The maximum of blue color varies with the maximum of heat. 

 The color is generally less intense in the afternoon than in the 

 morning. M. Crova leads us to conclude that in general the 

 sky is richer in blue rays than the sun. Certain observations 

 were made under a cloudy sky. The author states that the light 

 was less rich in blue rays than the blue sky but that it was more 

 blue than the light of the sun. — Comptes Rend us, No. 13, Sept. 

 23, 1889, p. 493. j. t. 



9. Passage of Electricity through gases. — At the late meeting 

 of the British Association, Professor Arthur Sinister gave an 

 account of his investigations on the distribution of potential in 

 the neighborhood of the negative pole of discharge of electricity 

 through rarified gases. " Knowing the rate of fall of potential, 

 it can be determined whether there is any bodily electrification in 

 any part of the negative glow. It was found that the kathode is 

 surrounded by an atmosphere of positively electrified gaseous 

 particles extending to the outer edges of the so-called dai'k space. 

 According to the author's views, this atmosphere corresponds to 

 the polarized layer adjoining the negative electrode in an electro- 

 lyte. The cause of the sudden difference in luminosity between 

 the dark space and the negative glow has also been investigated, 

 and it has been found that negative particles projected from the 

 kathode pass unhindered through the dark space, while their 

 velocity is quickly reduced in the glow proper, the translatory 

 energy being thus changed with energy of vibration." — Nature, 

 Oct. 10, 1889, p. 586. J. T. 



10. Purification of Sewage by Electricity. — A paper" was read 

 before the British Association, at its late meeting, on this subject, 

 by Mr. W. Webster, who showed that the effect produced was 

 due to the gases set free in the electrolysis of the sewage water. 

 The constituent parts of sodium, magnesium and other chlorides 

 are split up, nascent chlorine and oxygen are set free at the posi- 

 tive and the bases at the negative pole. — Nature, Oct. 24, 1889, 

 p. 631. j. t. 



11. 'Elementary Lessons in Heat ; by S. E. Tillmak, Professor 

 of Chemistry, U. S. Military Academy. 160 pp. 8vo. Philadel- 

 phia, J 889 (J. B. Lippincott Company). — These lessons, prepared 

 for the students of the \J. S. Military Academy, give in concise 

 form the general principles of heat. The ground covered is about 

 the same as that usually taken in the larger elementary text-books, 

 without too much mathematical analysis for the ordinary student, 

 and omitting the excess of descriptive and pictorial matter too 

 often present. Suitable use is made of the results of recent 

 work in the department of heat. 



