June 28, 18773 



NATURE 



167 



CHEMICAL NOTES 



On Errors in the Determination of the Densi- 

 ties OF Mixed Vapours. — In the Comfit. ./i<.-«i/., Ixxxiii., 

 Messrs. Troost and Hautefeuille record some experiments 

 made by them to discover the error which occurs in deter- 

 mining the vapour-density of substances by the appUcation 

 of the law of Dalton on the tension of mixed gases, and 

 Boyle and Gay-Lussac's laws, as applied to a mixture of 

 the vapour examined, either with air or with some other 

 vapour. They examined a mixture of carbon and silicium 

 chlorides, using a modified form of Gay-Lussac's vapour- 

 density apparatus. On increasing the amount of carbon 

 chloride, the tension of the silicium chloride diminished. 

 The vapour-density of silicium chloride alone varied only 

 (rom 5 "94 to 6'o, but in presence of carbon chloride was 

 found to mcrease 6'27 to 82. 



On the Properties of Ruthenium.— In the same 

 journal an account is given by Messrs. St. Claire- Deville 

 and H. Debray, on the physical and chemical properties 

 of the above metal. They find that the metal forms an 

 oxide RuOo, thus differing from osmium. By fusing the 

 pure metal with potash and saltpetre, then saturating the 

 rutheniate thus formed with chlorine, and distilling m a 

 current of the gas at about 80° C, they obtain the tetra- 

 o.xide RuOj in yellow crystals, which, when reduced, 

 yields the pure metal. The metal they obtained by puri- 

 fication from its alloy with zinc, was found to have a 

 density of i2"26i at 0°. They also obtained a compound, 

 Ru.jKjOg, in black crystals, on saturating the rutheniate 

 of potash with chlorine. For the analysis of ruthenium 

 ores, the process they employ is based on the foregoing 

 remarks. After the fusion of the ore with saltpetre and 

 potash, the whole mass is distilled with chlorine, the ex- 

 cess of gas, together with the RuOj, being absorbed by 

 solution of potash. The potash solution is then treated 

 with alcohol which precipitates the ruthenium as oxide, 

 and this is finally reduced to the metallic state with 

 hydrogen. 



Aconitic Acid in Cane Juice and Raw Sugar.— 

 In a late number of the American Chemist an account is 

 given by Dr. Arno Behr of some experiments he has con- 

 ducted on the above subject. For examining the pro- 

 perties of this acid he has found the so-called melado a 

 proper material, this substance being merely cane juice 

 boiled down to a concentration such as allows the sugar 

 to crystallise out, the mother liquor being then drawn off 

 and used for the production of the acid. The author has 

 analysed an acid substance formed by decomposing its 

 ammonia compound with sulphuric acid and extracting 

 with ether, and assigns to it the composition CgH^O^. He 

 has also prepared silver, calcium, and ammonium salts of 

 the acid body, the per centage composition of these salts 

 agreeing closely with the theoretical composition of the 

 silver, calcium, and ammonium aconitates. Although 

 from the results of his analyses he has no doubt of the 

 substance in question being aconitic acid, yet the melting 

 point, 172-173' C, which he found was not in accordance 

 with that generally given, viz., 140° C." ; the author there- 

 fore prepared some pure acid which had a melting point 

 of 168-169° C. The acid formed from aconitine fused 

 at 165° C. It is difficult, however, to determine the melt- 

 ing point as the acid is decomposed in the process of 

 melting. The author has found the melado to contain 

 o 149 per cent, of aconitic acid. The sweet waters 

 from charcoal filters used in refining raw sugar contain it 

 in an appreciable quantity, and some molasses sugars 

 give a peculiarly opaque solution from which a sandy 

 sediment is deposited, appearing under the microscope to 

 consist of small rhombohedral crystals, and which, on 

 analysis, proved to be calcium aconite. The author thmks 

 aconitic acid to be a normal constituent of sugar, and that 

 it is worthy of remark that the two plants yielding the 

 most sugar — the beet-root and sugar-cane — also produce 



two acids standing so chemically near each other as 

 citric and aconitic acids, and which contain in their 

 molecules the same number of carbon atoms as fruit 

 sugar. 



Minerals containing Columbium from New 

 Localities in the United States.— Mr. J. L Smith, 

 of Louisville, has examined several species of minerals 

 containing columbium, and claims the restoration of this 

 name for the metal instead of that of niobium, generally 

 given to it in England and on the Continent. His reason 

 for making this reclamation is that the name niobic acid 

 was incorrectly given by H. Rose to one of the acids 

 found by him in his researches on the columbite of Bode- 

 mais, and subsequently proved by him to be identical 

 with the columbic acid originally discovered by Hatchett 

 in iSoi. The name niobic acid, ho>vever, given by Rose, 

 has never been altered, and Mr. Smith thinks the original 

 columbic acid should have been retained. In remarks on 

 the chemical constitution of the minerals described by 

 him, Mr. Smith thinks that the composition of the colum- 

 bates, although appearing at first sight complex and 

 irregular, becomes much simpler when due allowance is 

 made for the intermixture of the different varieties with 

 each other. Columbite, the best known of the minerals, 

 can be well recognised as a simple columbate of iron and 

 manganese ; microlite appears to be a columbate of lime ; 

 pyrochlore, a columbate of the cerium oxides and lime, 

 but whether or not a neutral columbate remains to b; 

 investigated. Hatchetolite he considers as a neutril 

 columbate of uranium and lime, and samarskite a ba=ic 

 columbate of iron, uranium, and yttrium oxides. Yttro- 

 tantalite and euxenite are basic colambates of yttrium 

 and uranium, the first being anhydrous when pure, the 

 second containing water. Fergusonite js a hydrated 

 basic columbate of yttria, and Rogersite, a columbate still 

 more basic. In arranging a general view of these minerals 

 Mr. Smith does not take into account the constituents 

 which exist in small quantities only. 



Coefficient of Capillarity for Certain 

 Liquids. — M. Gueront, in the Comptes Rendus (Ixxxiii. 

 1 291) describes experiments in which he finds that in any 

 series of organic compounds the coefficient of capillarity 

 decre ises as the amount of carbon in the substance in- 

 creases. He has examined three series of bodies, the 

 fatty acids, the acid ethers of ethylic alcohol, and the 

 ethers formed by the union of acetic acid with the different 

 fatty alcohols. In the series of fatty acids those members 

 above propionic acid agree with the above statement, but 

 the two lowest members, acetic and propionic acids, are 

 exceptions ; this he thinks probably due to impurities ; the 

 two series of ethers, however, agree perfectly with the law. 

 From his observations it becomes evident that the coeffi- 

 cient of capillarity of the ethers is higher than that of the 

 alcohols or the acids from which they are formed, showing 

 that the introduction of an organic radical into the alcohol 

 molecule renders the body more fluid. On comparing the 

 two series of ethers it was found that the isomeric ethers 

 have nearly the same coefficient, but the acids isomeric 

 with them are much lower. Thus valeric acid, which is 

 isomeric with ethyl propionate and propyl acetate, has a 

 coefficient only about one quarter that of these latter. 

 The reason suggested for this difference is that in the two 

 isomeric ethers atoms are grouped in a similar way, 

 while in the isomeric acids the grouping is dirterent. 



METEOROLOGICAL NOTES 



Sun-Spot Periods and Auroras from 1773 to 1827. 

 — We have received a communication from Mr. Buchan 

 inclosing the following table, showing the numOer of 

 auroras observed by Mr. James Hoy at, or in the vicinity 

 of, Edinburgh, each year from 177310 I78i,andat Gordon 

 Castle, Banffshire, from 17S1 to 1S27 : — 



