74 



SCIENCE. 



[Vol.. I., No. 3. 



the units of length and time entered into tlie experi- 

 ments. — {Johns Hopk. univ. sc. assoc. ; meeting 

 Jan. 3.) [19* 



EWGIITEEEIIfG. 



Automatic inspection of rail-ways. — The jire- 

 cise methods of modern physical research are fast 

 invading the various fields of practical science, and 

 enabling us to be more and more independent of 

 guesswork every year. Nothing illustrates this more 

 forcibly than Mr. P. H. Dudley's dynamometer car, 

 which is drawn from one end to the other of any 

 railway, and, as it goes, records automatically every 

 imperfection existing in the track, and at the end of 

 the trip presents a long roll of paper which is a com- 

 plete telltale in regard to the exact state of the road. 

 Every bad joint, every defective rail, every lack of 

 correct alignment, either vertical or horizontal, is 

 shown upon the diagram in such a manner as not 

 only to indicate the precise location of the defect, 

 but at the same time to suggest the remedy. The 

 dynamometer car has been employed upon a great 

 many of our more important railroads, with the most 

 satisfactory results. — G. L. v. [195 



Railway management as a science. — Ai-t first, 

 and scii'nce afterwards, has been the rule in all tech- 

 nological pursuits, to which railways are no excep- 

 tion. We are fast accumulating sufficient data to 

 show that there is such a thing as a science of rail- 

 way operation; and just as soon as tlris fact is 

 recognized, this science will find a place in our tech- 

 nical schools. The ArcMv fur eisenbahnwesen, a 

 periodical issued by the Prussian ministry of puljlic 

 works, announces that there will be in the winter 

 semester of the universities of I3erlin and Breslau, 

 courses of lectures on railroad operation, including 

 station and train service, signalling, organization 

 and duties of employees, and railway mechanism; 

 and also lectures on railway administration, includ- 

 ing the arrangement of rates and fares, the discus- 

 sion of wages, and railway statistics. A third course 

 will be on railway law, and a fourth on railway trans- 

 portation as a branch of political economy. — a. L. v. 



[196 

 CHEMISTRY. 

 (General, physical, and inorganic.) 



Magnesium carbonate. — H. Beckurts has ob- 

 tained the normal magnesium carbonate Mg C O3. 

 3 H.2O by heating a solution of the bicarbonate to 

 70°. From a boiling solution the precipitate thrown 

 down had the same composition (5 Mg C O3. 2 Mg 

 (0H).2, 7 H2O) as magnesia alba jirepared according 

 to Pattinson's method. — (Ckem. tech. repert., xx. ii. 

 2, 149. ) c. F. 51. [197 



Investigations on chlorine and bromine. — 

 Determinations of the vapor density of chlorine and 

 bromine when mixed with air, by C. Danger and v. 

 Meyer, gave values corresponding to CL and Br^. 

 It is proposed to determine whether at high tempera- 

 tm-es these substances, like iodine, will give a vapor 

 density corresponding to the half molecule. — (Be- 

 richte deutsch. chem. gesellsch., xv. 2769.) c. F. M. 



[198 



Congelation of solvents. — In experiments upon 

 the point of congelation of water, formic acid, acetic 

 acid, benzol, nitro-benzol, and etbylen dibromide, M. 

 Kaoult tried the action of each solvent upon two 

 hundred other substances. A solution of one grm. 

 substance in 100 grms. of the solvent gave results 

 from which the following law was deduced : A mole- 

 cule of any substance whatever, when dissolved in 

 100 molecules of any liquid of a different nature, 

 lowers the point of congelation of the liquid 0°.62, 



— a value nearly constant for different solvents. — 

 {Comptes rendus, xcv. W^O.) c. r. m. [199 



Formation of active oxygen. — Eesults ob- 

 tained by Moritz Traube show that ozone is not 

 produced by hydrogen in statu nascendi. The hy- 

 pothesis of Hoppe-Seyler, that chemical processes 

 which take place within the bodies of animals are 

 identical with those resulting from putrefaction, and 

 depend upon the i^resence of ozone produced by nas- 

 cent hydrogen, must therefore be incorrect. In sup- 

 port of this hypothesis, Hoppe-Seyler asserted that 

 nascent hydrogen from palladium-hydrogen would 

 convert oxygen into its active condition. The author 

 finds that hydrogen is not evolved from the alloy at 

 ordinary temperatures, and that instead of ozone, in 

 presence of water, hydrogen peroxide is formed. 

 Other results seem to indicate that hydrogen per- 

 oxide is a product of reduction rather than of oxida- 

 tion. — {Berichte deutsch. ckem. gesellsch., xy. 2421.) 



C. F. M. [200 



Influence of pressure on the speed of chemical 

 action. — Prof. R. B. Warder made the following 

 remarks: " Menschutkin ^ lias recently published liis 

 experiments on the decomposition of tertiary amyl- 

 acetate by heating in sealed tubes. At 155° C, while 

 the jjressure was gradually increased by the formation 

 of amylene, the speed of the reaction was found to 

 increase until about half the ether was decomposed. 

 Menschutkin's graphical representation of the prog- 

 ress of the reaction has a point of inflection at this 

 stage. This fully accords with the theory of ' action 

 of mass ' if we assume that this reaction, like many 

 others, is promoted by pressure. 



If the speed of the reaction is directly proportioi\aI 

 to the pressure, and if the increase in pressure is 

 proportional to the amylene generated, the course of 

 the reaction should be represented by the equation, 



log 



— log- 



At. 



Where 11 is the quantity of ether still present at 

 any moment, to be eventually decomposed within 

 the limit of the reaction, tto is the initial value of u ; 



t is the time of action ; 



is the ratio of initial 



to final pressure; and A is a constant, dependent upon 

 the actual pressure, as well as the absolute coefficient 

 of speed. 



By making m = I.OIm,,, and A = 0.04, we obtain an 

 equation which pretty closely agrees with Menschut- 

 kin's curve. — (Ohio inech. inst. ; sect. chem. phys. ; 

 meeting Jan. 18.) [201 



{Organic.) 



Caffeine, theobromine, xanthine, and guanine. 

 — In an extended investigation upon the constitution 

 of these substances, Emil Fischer examined many of 

 their derivatives and decomposition-products. Oxi- 

 dation of caffeine with hydrochloric acid and potas- 

 sium chlorate gave methylurea and amalic acid. 

 This acid, without doubt, was formed directly from 

 dimethylalloxan, in a manner analogous to the for- 

 mation of alloxantine by beating alloxan with hydro- 

 chloric acid. By oxidation with nitric acid, amalic 

 acid was converted into dimethylalloxantine, which 

 formed cholestrophan by further oxidation. In the 

 oxidation of theobromine, the resulting methylal- 

 loxau was immediately changed into the correspond- 

 ing alloxantine, whicli gave methylparabanic acid by 

 oxidation. Methylurea also was identified as a 

 product of the oxidation of theobromine. As the 

 decomposition-products of xanthine, alloxan was 

 I Ber. chem. gesellsoh. xv., 2512-2518. 



