212 



NATURE 



[December 27, 1900 



Jan. 15. Venus. Illuminated portion of disc = 0*902, Mars 

 = 0-949. 



17. 2ih. Jupiter in conjunction with moon. Jupiter 



2° 13' S. 



18. 2h. Venus in conjunction with moon. Venus 



2° 12' S. 



18. l6h, Saturn in conjunction with moon. Saturn 



2° 41' S. 



19. iSh. 37m. to 2ih. 2im. Transit of Jupiter's Sat. 



III. 

 24. 8h. Venus in conjunction with Saturn. Venus 

 0° 20' S. 



28. 8h. 3m. to 8h. 28m. Moon occults 13 Tauri 



(mag. 5-4). 



29. 6h. om. to 6h. 37m. Moon occults DM + 20, 785 



(mag. 5-8). 



30. I4h. 41m. to I5h. 36m. Moon occults x^ Orionis 



(mag. 47). 



Ephemeris for Observations of Eros. — The following 



is an abridgment of Herr Millosevich's ephemeris for 

 January : — 



Ephemeris for \2h. Berlin Mean Time. 



1901. R.A. Decl. Mag. 



h. m. s. o / // 



Jan. I ... 2 3 52-80 ... +37 55 14-5 



3 ... 9 280 ... 37 3 39-5 ... 8-44 



5 ... 14 27-17 ... 36 12 7-3 



7 ... 20 4-92 ... 35 20 39-0 ... 8-45 



9 ... 25 5S-2I ... 34 29 158 



II ... 31 57-23 ... 33 37 59-2 ... 8-45 



13 ... 38 10-17 ... 32 46 505 



15 ... 44 33-19 ... 31 55 51-2 ... 846 



17 ... 51 5-61 ... 31 5 3-0 



19 ... 2 57 46-65 ... 30 14 27-1 ... 8-47 



21 ... 3 4 35-62 ... 29 24 54 



23 ... II 31-79 ... 28 33 593 ... 8-49 



25 ... 18 34-34 ... 27 44 lo-i 



27 ... 25 42-53 ... 26 54 39-0 ... 8-52 



29 ••• 32 55-50 ... 26 5 26 8 



31 ... 3 40 12-48 ... +25 16 34-8 ... 8-55 



Diameter of Venus. — In the Ash-onomische Nachrichten 

 (Bd. 154, No. 3676) Prof. T. J. J. See announces the results of 

 a long series of measurements of the diameter of Venus, made 

 with the filar-micrometer on the 26-inch refractor of the 

 U.S. Naval Observatory at Washington. He also prefaces his 

 remarks by a rhumi of the observations of the diameter which 

 have been made since the time of Galileo (1620). 



The difficulties of the determination are summarised thus : — 



(i) The enormous change in the geocentric distance of the 

 . planet renders the apparent diameter extremely variable. 



(2) The thin line-like horns presented when the planet is 

 near inferior conjunction are easily affected by atmospheric 

 disturbances, rendering bisection with the micrometer wire 

 difficult. 



{3) As the crescent enlarges the diameter decreases. 

 • (4) Near superior conjunction, although the disc is nearly 

 round, its diameter is so small, and the time of observation is 

 necessarily such that the heated atmosphere has a great 

 disturbing effect on the definition. 



(6) Irradiation, which is always great on account of the 

 brilliancy of the planet. 



Much of the difficulty due to the brilliancy has been eliminated 

 by the use of coloured screens between the eye and telescope, as 

 described in A.N. Nos. 3636, 3665. 



The mean of Prof. See's determinations on 22 days gives a 

 mean diameter of 



1 6" -80° + o"-022 



which is in close agreement with the value 16-820 deduced by 

 Dr. Auwers in 1894 from the transits of Venus in 1874 and 1882. 

 Several suggestions are included comparing the work with 

 heliometer and filar micrometer on planetary diameters, the two 

 giving variable results with different planets. 



Reduction of Occultations.— -M. L. Cruls, director of the 

 Observatory of Rio Janeiro, has published an improved method 

 of time determination from lunar occultations, based on the 

 exact knowledge of the instant of apparent conjunction of the 

 two bodies. The formulae of Bessel are slightly modified, and 

 both analytical and graphical solutions given at length, with 

 examples of each. 



NO. 1626, VOL. 63] 



NATURAL AND ARTIFICIAL PERFUMES. 

 'T'HE passing century has seen the rise and subsequent decay 

 -*■ of several great branches of chemical industry. Early in 

 the century, when the chemical methods applicable to the 

 manufacture of alkalis and of alkali products were being actively 

 developed, profits were large, whilst now that the chemical 

 difficulties encountered in the manufacture of alkali have been 

 practically overcome, the financial prosperity of an alkali works 

 depends mainly upon economy in carrying out certain engineer- 

 ing processes ; the science of the chemist is now of rather less 

 importance than the art of the engineer. The younger industry 

 of coal-tar dye-stuff manufacture is similarly, though more 

 gradually, developing into a branch of engineering, and in conse- 

 quence money is not made so rapidly as was once the case. 

 During the last twenty-five years a new chemical industry, that 

 concerned with artificial perfumes, has made rapid progress and 

 would seem to give more promise of both chemical and financial 

 prosperity than either of its elder sisters. Perfumes are only 

 needed in small quantities, but, in accordance with the law that 

 anything ministering to our pleasures fetches a far higher price 

 than a mere article of utility, profits upon a really gigantic scale 

 may be easily obtained ; again, the enduring chemical prosperity 

 of the new industry is assured in that a constant succession of 

 new perfumes is absolutely necessary ; by the time that im- 

 proved methods of manufacture and competing processes have 

 lowered the 'price of a perfume, the material has become un- 

 fa.shionable. No lady would use a cheap perfume. Further, 

 the sense of smell in man is as yet wholly uncultured ; in walk- 

 ing through the country we can rarely identify a particular 

 odour caught until the sight of the plant from which it emanates 

 makes us wonder at our hesitation. The coal-tar colour industry 

 found us provided with a highly-developed system of colour per- 

 ception, whilst the newly-inaugurated artificial perfume industry 

 has to cultivate a neglected sense probably possessing similar 

 artistic potentialities. 



The scientific methods adopted in the new industry consist, 

 in the main, of three : (i) in the extraction of odoriferous com- 

 pounds from the natural products in which they occur ; (2) in 

 the artificial preparation of naturally occurring odoriferous com- 

 pounds by synthetic processes ; and (3) in the manufacture of 

 materials possessing odours resembling those of naturally occur- 

 ring substances of pleasant smell. The odoriferous principle of 

 bitter almond oil was one of the first isolated and subsequently 

 synthesised ; the oil was obtained during the Middle Ages by 

 distilling bitter almonds with water, whilst, nowadays, only very 

 small quantities are prepared from the almond. Apricot kernels 

 are first freed from fatty oils by hydraulic pressure, and then 

 caused to undergo a fermentative process. The kernels contain 

 a glucoside, amygdalin, which, at a suitable temperature, is 

 hydrolysed by an unorganised ferment, emulsin, also present, 

 with formation of benzaldehyde, QH5.CHO, hydrogen cyanide 

 and grape sugar, in accordance with the equation 



CsoHa^NOu + 2H2O = CeHj-CHO + 2C6Hi20e -1- HCN. 

 The mass is then distilled in a current of steam, and the resulting 

 oil separated from the aqueous distillate and freed from the 

 prussic acid which it still retains. Liebig and Woehler first 

 separated pure benzaldehyde from crude bitter almond oil in 

 1832. Benzaldehyde is prepared on a large scale by the 

 hydrolysis and oxidation of benzyl chloride by boiling it with 

 cupric or lead chloride solution ; the artificial oil retains with 

 great tenacity traces of benzyl chloride, and the penetrating, 

 unpleasant odour of this impurity renders the product fit only 

 for scenting common soaps and prevents its use in perfumery. 

 Nitrobenzene, CgHg.NOg, the highly poisonous so-called oil of 

 mirbane, has an odour very similar to that of benzaldehyde, and 

 is sometimes used in its place. 



Vanillin, the odoriferous principle of the vanilla bean, is an 



HO, 



, and was artifi- 



aldehyde of the constitution 



CH3OL yCHO 



cially prepared in 1874 by Tiemann and Haarmann ; the 

 original method of preparation consisted in oxidising coniferin, 

 a glucoside contained in the sap of various conifers, with 

 chromic acid. Many different methods of preparing vanillin 

 have been patented ; but it seems now to be mainly obtained 



from eugenol. 



HO 

 CH3OI JCH2.CH:CH2, 



a phenol contained 



