8(H) 



SCIENCE. 



[Vol. II., No. 46. 



ure of steam gave E natural; 80 pounds, F sharp; 90 

 pounds, G; 110 pounds. A; and 12.5 to 130 pounds gave 

 C sharp in alt. The distance from steam-opening to 

 edge of whistle was 1 J inches. When it was increased 

 to 2 inches, the power of the sound was sensibly les- 

 sened, but the pitch was altered relatively but half a 

 tone. If the distance were decreased to 1 inch, or to 

 j of an inchf the whistle would sound only super- 

 tones. The notes above were clear, even ' reedy,' 

 and could be heard six miles. A bell of brass tubing, 

 annealed, hammered, and then heated again, gave 

 sounds of somewhat greater intensity and pitch. An 

 iron bell was unsatisfactory. — {Railr. gaz., Aug. 31.) 



C. E. 6. [507 



Economy of pumping-engines. — Mr. P. A. 



Korevaer compares the economy of the scoop-wheel, 

 the Archimedean screw, the pump-wheel, the suction 

 or bucket pump, the double-action pump, and the 

 centrifugal pump, and reports the results to the Dutch 

 institute of engineers. In the Netherlands the pump- 

 wheel is used for lifts less than 2. -5 metres (8.3 feet), 

 and the screw for about 4.25 metres {12.5 feet) ; while 

 the lift and volume delivered by the ordinary forms 

 of pump are unlimited. The economical lift for a 

 centrifugal pump is taken to be as a maximum at about 

 30 or 40 feet. Its cost in Holland is rather greater 

 than that of a scoop-wheel. The latter gives an 

 efficiency of 64 to 69.5 % on lifts varying from 4 to 

 6 feet (1.2 to 1.8 metres). The double-acting pump 

 gives an eflBciency of 67 to 73 % on lifts between 6.66 

 and 10 feet (2 to 3 metres). The centrifugal pumps 

 tested gave from 17 to 70 % (averaging 45) in one 

 place, and 40 to 49.3 (averaging 44) in another case. 

 The coal used amounted to from 0.9 to 1.2 kilogr. with 

 scoop-wheels for the drainage of one hectare and a 

 lift of one metre, 1 to 1.17 with double-acting piunps, 

 and 1.56 to 2.19 with centrifugal pumps. The author 

 concludes that a decided gain is obtained by the use 

 of other methods of pumping rather than by the 

 use of the centrifugal pumps, — a conclusion which we 

 may be allowed to agree in, with the qualification that 

 the results would bear a somewhat dififerent com- 

 plexion if the comparison were with efficient cen- 

 trifugal pumps, which should be capable of giving an 

 efficiency of at least 66 %. — (Ahs. papers Inst. civ. 

 eng., 1882-83, iii.) b. ii. t. [508 



Electric head-light for locomotives. — The 

 Sedlaczek head-light was exhibited at Munich at the 

 late exhibition. It was made by Messrs. Sedlaczek 

 & Wilkulill, as a modificatiou of the lamp of Lacas- 

 sagne & Thiers, of 1856. The current is supplied by 

 a dynamo placed on the top of the boiler behind the 

 smoke-stack, and driven by an independent engine. 

 The lamp is arranged to turn automatically on curves 

 so as to light the track at all times. The light was 

 visible at a distance of 2i miles (4 kilometres). The 

 report of the committee intrusted with the observa- 

 tion of the action of the lamp states that the in- 

 tensity (4,000-candle power) was so great that the 

 guards reported that it dazzled their eyes to such an 

 extent that they were unable to make the observations 

 prescribed by the regulations. The committee ex- 

 press a fear that it may frighten horses. Their appre- 



hensions remind us of the same difficulties as they 

 presented themselves to the opponents of the railway 

 itself. A report made on this lamp in 1881, when 

 used on the Northern railway of France, stated that 

 the experiment proved that the lamp was not extin- 

 guished by the jar of the train, and that it did not in 

 any way affect the visibility or the appearance of 

 colors in signals. Engineers of trains were not daz- 

 zled by it unless by looking at it persistently, and were 

 not prevented, even then, from seeing the signals. 

 It is proposed to apply the same system of lighting to 

 the cars. — {Raihoay rev., Oct. 6.) b. h. t. [509 



CHEMISTRY. 

 (Organic.) 

 Constituents of petroleum from Galicia. — In 



the oil from this locality Br. Lachowicz has found a 

 normal, and an iso-pentan, two hexans, one heptan, 

 one uonan, and two decans. Other hydrocarbons of 

 this series were present in smaller quantity. No 

 members of the ethylen series were detected. Of the 

 aromatic hydrocarbons, benzol, toluol, isoxylol, and 

 mesitylen were identified. The quantity of 'Wre- 

 den's hydrocarbons ' — hexahydrobenzol (CiHi^), 

 hexahydrotoluol (C7 Hi 4), and hexahydro-isoxylol — 

 in the Galicia petroleum lies between that of the Cau- 

 casus and the American oils. — {Ann. chem., 220,108. ) 

 C. F. M. [510 



Compounds of the indigo group. — In the 

 course of his investigations upon the constitution 

 of indigo, A. Baeyer has tried several reactions to 

 determine the position of the hydrogen atom which 

 is not in the benzol ring. If the formula 

 CeH, — CO 



I I 



If =COH 



is assigned to isatin, the isomeric form called by 

 Baeyer pseudo-isatin would have the form 

 CjH. — CO 



I I ; 



HN— CO 

 and the form of pseudo-indoxyl isomeric with in- 

 Joxyl, 



CcH. — COH 



I II 

 HN— CH 



would be 



C„H, — CO 



I I 

 HN — CH, 



Baeyer draws the following conclusions from his 

 results concerning the structure of indigo : — 



1. It contains an imido group. 



2. The carbon atoms have the arrangement 



CaHj — C — C — C — C — CjHj. 



3. It is formed only from compounds in which the 

 carbon atom next to the benzol ring has attached to 

 it an oxygen atom. 



4. In its formation and properties it is closely re- 

 lated to indirubin and the 'iudogenides' of ethyl- 

 pseudo-isatin. 



5. The latter results from a union of the a-carbon 

 atom of pseudo-indoxyl with the j8-carbon atom of 

 pseudo-isatin. 



