Mat 11, 1883.] 



SCIENCE. 



401 



the fourth iXegree. — { Phil. soc. Wash., math, sect; 



meeting April 26. ) [811 



PHYSICS. 



Electricity. 



Testing insulation of electric-light wires. — 

 Mr. C. J. H. Woodbury described a compact piece of 

 apparatus, consisting of a magneto-electric machine 

 and a pair of electric bells. The machine will pro- 

 duce a current strong enough to ring the bells through 

 a resistance of seven thousand ohms. By connecting 

 one pole with the electric-light system, and the other 

 with the ground, the insulation of the system may 

 be shown to be more or less than about seven thou- 

 sand ohms, according as the bells ring or not. The 

 method has been found useful in the inspections now 

 made in the interest of fire-insurance companies. — 

 {Frankl. inst., meeting April IS.) [812 



Electrical transmission of power. — Dr. C. W. 

 Siemens, in the course of an address at the Institu- 

 tion of civil engineers on March 1.5, after describing 

 the well-known experimental electrical railways of 

 the Berlin and Paris exhibitions, stated that an eleg- 

 trical railway six miles in length had just been com- 

 pleted in the nortli of Ireland. In this instance the 

 two rails, three feet apart, were not insulated from the 

 ground, but were joined electrically by means of 

 copper staples, and formed the return circuit, the 

 current being conveyed to the car through a T ii'on, 

 placed upon short standards, and insulated by means 

 of insulite caps. For the present the power was pro- 

 duced by a steam-engine at Portrush, giving motion 

 to a shunt-wound dynamo of 15,000 Watts, or 20-horse 

 power. The working-speed of this line was restricted 

 by the board of trade to ten miles an hour, whicla was 

 readily obtained, although the gradients of the line 

 were decidedly unfavorable, including an incline of 

 two miles in length at a gradient of 1 in 38. It was 

 intended to extend the line six miles farther, in order 

 to join another railway system. The electric system 

 of propulsion was, in the lecturer's opinion, siiflB- 

 ciently advanced to assure practical success under 

 suitable circumstances ; such as for suburban tram- 

 ways, elevated lines, and, above all, lines through tun- 

 nels. The lecturer, however, did not advocate its 

 prospective application in competition with the loco- 

 motive engine for main lines of railway. — {Nature, 

 March 29.) b. h. h. [813 



ENGINEERING. 

 Stadia reductions. — Mr. Arthur Winslow pre- 

 sented, and described the derivation of, tables for 

 stadia reductions, wliich furnish expressions for hori- 

 zontal distances and differences of elevation, cor- 

 responding to 100-toot stadia readings for 2" up to 

 30°, on the supposition that the rod be held verti- 

 cally, and the stadia wires be equidistant from the 

 centre wire. They are not mere reductions of in- 

 clined distances to their horizontal and vertical com- 

 ponents, but embody certain corrections necessary 

 from the facts, 1°, that with horizontal sights the 

 length cut off by tlie stadia wires on the rod is not 

 directly proportional to its distance from the centre 

 of the instrument, but from a point at a distance in 

 front of the object-glass equal to its principal focal 

 length; and, 2°, that witli inclined sights a correc- 

 tion has to be made for the oblique view of the rod. 

 Both the distances and elevations in these tables are 

 given in feet. They are adapted to use with a tele- 

 scope whose object-glass has any focal length, and 

 with a rod which is so graduated that the spaces cut 

 off on it by the stadia wires are directly proportional 

 to its distance from a point at a distance in front of 



the object-glass equal to its principal focal length, 

 differing in these respects from the tables issued by 

 the engineer department, U.S.A. — {Eng. club Phil- 

 ad.; meeting April 7.) [814 



CHEMISTRY. 

 (Oi-ganic.) 



Constitution of atropine. — A. Ladenburg proved 

 that tropine is a tertiary base, since it would not 

 unite with more than one molecule of ethyl iodide, 

 and it was not affected by nitrous acid. By the action 

 of chlorhydropasic acid upon it, a tropasate of tropine 

 was formed; and, when treated with dilute hydro- 

 chloric acid, the latter substance was converted into 

 atropine, which separated in beautiful, crystals on 

 evaporating the solution. 



This product proved to be identical, in its chemical 

 as well as in its physiological characters, with natural 

 atropine prepared from belladonna. A series of de- 

 rivatives, called by the author tropeines, results from 

 the action of various organic acids with hydrochloric 

 acid upon tropine. To establish the constitution of 

 tropasic acid, it was prepared by the action of potassic 

 cyanide in alcoholic solution upon chloracetophenon, 

 and treating the product with baric hydrate. The 

 resulting atrolactinic (or tropasic) acid was also made 

 from hydropasic, and it was converted into atropasic 

 acid. Since, furthermore, atropasic was converted 

 into tropasic acid, the formula of the latter must be 



CgHsCH^^^Qg. When distilled with soda-lime, 



tropine is decomposed, giving methylamine and tro- 

 pilidine (CjHs); and, when treated with fuming hy- 

 drochloric acid, a volatile base, tropidine (CsHuN), 

 is formed. By the action of hydriodic acid and red 

 phosphorus, hydrotropine iodide (CsH,7NI) results. 

 Tropine is thus shown to contain an hydroxyl group; 

 and the above-mentioned synthesis of atropine, and 

 the formation of the tropeines, are explained : — 

 0„H,iNOH C8Hi,NO(C3Ha02) CsHuNOCCgHvOz) 



Tropine. Atropine. Homatropine. 



The tropeines are therefore ethers of tropine, which 

 is a nitrogen-containing alcohol. When heated with 

 bromine, tropidine is decomposed, with the formation 

 of ethylen bromide and dibrompyridine (CjHsBroN). 

 The author is at present engaged upon the synthesis 

 of tropine from pyridine. — (Ann. chem., ccxvii. 74.) 

 c. p. M. [815 



Protocattannic acid and anhydrides of the 

 aromatic oxy-acids. — Hugo Scliiff states, that, 

 when protocatechuic acid in aqueous solution is boiled 

 with arsenic acid, a substance is formed, with the 

 formula of diprotocatechuic, or protocattannic acid 

 (2 CHgOj — H20 = Ci4Hio07). The solution pos- 

 sesses the general reactions characteristic of tannin; 

 and mineral acids reprecipitate protocatechuic acid. 

 When protocatechuic acid in etherial solution is acted 

 upon by phosphorous oxychloride, tetraprotocatechuic 

 acid is formed (4 CyHeOj- 3 H^O = CosH, gO, 3). 

 The solution fluoresces, and its reactions in general 

 are characteristic of tannin. If an intimate mixture 

 of protocatechuic acid and dry arsenic acid is heated 

 to 160°, acatelagic acid corresponding to elagic is pro- 

 duced (2C,He04-(H,0-|-Ho) = C,4H,o07). — (G'az. 

 chim. ital., 1883, 90; Berichtedeutsch. chem. gesellsch., 

 XV. 2588. ) c. F. M. [816 



Action of cyanogen chloride on pyrrol-potas- 

 sium. — By the action of dry gaseous cyanogen chlo- 

 ride on pyrrol-potassium, Ciamician and Dennstedt 

 find that the cyanogen molecule is introduced, forming 

 cyanpyrrol or tetrolcyanamide. This substance poly- 

 merizes at the point of fusion, with the formation, 

 probably, of tetrolcyanuramide or tetrolmelamine, 



