Chemistry and Physics. 479 



violence. It explodes when mixed with combustible matter. 

 Nitro-nickel is similarly prepared and has similar properties. 

 Nitro-iron is more difficult to prepare, deflagration taking place 

 after the absorption of a portion of the peroxide. — Bull. Soc. 

 Chim., Ill, ix, 669, Sept. 1893. a. f. b. 



8. On the Preparation of Ethyl ether. — It has been pointed 

 out by Krafft that in the preparation of ether by means of 

 sulphuric acid, the acid is partly reduced to sulphurous acid by 

 the alcohol. Since the aromatic sulphonic acids are moi - e stable 

 in presence of alcohol, the author proposes their use for the con- 

 tinuous etherification of alcohol. Using ethyl alcohol and ben- 

 zene-sulphonic acid for example the reaction is : (1) PhS0 2 . OH 

 + EtOH = PhS0 2 .OEt + H 2 0; and (2) PhSO . OEt + EtOH = 

 PhS0 o . OH + Et 2 0. In practice the alcohol is dropped on the 

 benzene-sulphonic acid heated to 140°. ' Methyl-propyl ether was 

 thus produced and boiled at 36-6°-37'4°. — Ber. Berl. Chem. (res., 

 xxvi, 2829, Dec, 1893. G. F. B. 



9. Line Spectrum of Oxygen. — M. Eisig has taken up the sub- 

 ject anew with the aid of a Rowland concave grating and with 

 Rowland's map of the solar lines. An analysis of the work of 

 Schuster, Deslandres, Trowbridge and Hutchins, and Hartley and 

 Adeney is made, and the author is forced to the conclusion that 

 there is no positive evidence that oxygen exists in the sun. — Ann. 

 cler Physik unci Chemie, No. 4, 1894, pp. 747-760. j. t. 



10. Lilienthal'' s experiments on flying. — With the conviction 

 that the flight of birds is an art which must be carefully studied, 

 Lilienthal has practised himself in taking advantage of the 

 remarkable fact discovered by Langley and by himself that with 

 certain angles of inclination of wings to the direction of the 

 wind, not only does the horizontal component of the wind disap- 

 pear, but even may become negative, that is the fans which act 

 as wings fly against the wind and can be raised by it. He 

 accordingly selects a gentle incline free from woods or other 

 obstruction to the free movement of the wind. This incline was 

 usually not more than 10 or 15° to the horizon and ran against 

 the direction of the wind. After some experience Lilienthal was 

 enabled to soar distances of 120 to 150 meters against the wind. 

 Professor A. du Bois Reymond states that after only four or five 

 trials he was enabled to take leaps of from 15 to 20 meters long. 

 Lilienthal by means of stronger winds has been enabled to soar 

 in circles like those of birds similar to the hawk. If this prac- 

 tise of soaring is introduced as a sport, its use and the accumu- 

 lated experience of many young athletes, may lead to our learn- 

 ing the art of flying. Prof, du Bois Reymond calls attention, in 

 this connection, to the great skill that has been acquired in the 

 art of balancing oneself on bicycles and similar machines. — Phys- 

 ical Society of Berlin, Dec. 15, 1893. Ann. cler Physik unci 

 Chemie, No. 4, 1894, p. 42. j. t. 



11. Apparatus for the demonstration of Amperes laws. — In 

 order to avoid the disturbances which arise from the use of mer- 



