CHEMISTRY. 



105 



through the connecting tube against the surface 

 of the NH 3 solution in the other flask, dense 

 white fumes of NH 4 N0 3 are produced, and bub- 

 bles may be blown with the gas from the second 

 bottle. Such bubbles are more readily visible by 

 daylight or gas light, and are more satisfactory 

 for use before large audiences. 



A method for detecting and determining so- 

 phistication of linseed oil by resin oil, given by 

 M. A. Aignan, depends upon the fact as substan- 

 tiated by the author that pure linseed oil has no 

 rotatory power, while resin oil and mixtures of 

 resin oil with linseed turn the plane of polariza- 

 tion to the right in proportion to the quantity 

 of resin oil contained. A formula is given for 

 the quantitative estimation of the adulteration. 



L. Prunier has devised a process for making 

 a simultaneous determination of carbon and sul- 

 phur in organic substances which he finds to 

 be more manageable, expeditious, and accurate 

 than the old one of two separate determina- 

 tions. 



Atomic Weights. The atomic weight of 

 tellurium, as determined thus far, appears to be 

 greater than that of iodine, though the results 

 obtained by different investigators vary between 

 wide limits (126-39 by Wills to 128-9 by Berze- 

 lius). But from the arrangement of the elements 

 according to the periodic system we should expect 

 tellurium to fall in the same family as sulphur 

 and selenium, and therefore to have an atomic 

 weight between that of antimony and that of 

 iodine, or of about 123-5. Prof. B. Brauner under- 

 took an investigation in order to make a revision 

 of the atomic weight of the substance. The re- 

 sults of various methods tried were very dis- 

 cordant, and ranged from 124-6 to 129-63. They 

 seemed, however, to give one rule of variation, 

 and showed that " if tellurium, obtained by any 

 process of fractionation whatever, be subjected 

 to distillation in a current of hydrogen, and the 

 tetrabromide be prepared from this by sublima- 

 tion in a vacuum, its analysis always gives the 

 same atomic weight for tellurium. If, however, 

 the tellurium be only fused in a current of an in- 

 different gas and the tetrabromide be not sub- 

 limed higher numbers will be obtained." From 

 the widely divergent results obtained by the dif- 

 ferent methods the author concludes that tel- 

 lurium is not a simple substance. 



In a paper on the molecular weights of met- 

 als when in solution, C. T. Heycock and F. H. 

 Neville give the results of their observations on 

 the effect of various proportions of silver, gold, 

 copper, nickel, sodium, palladium, magnesium, 

 zinc, lead, cadmium, mercury, bismuth, calcium, 

 indium, aluminum, and antimony on the solidi- 

 fying point of tin. Of all these metals, antimony 

 alone behaves abnormally, producing a rise in- 

 stead of a depression in the solidifying point. 

 In the majority of cases the atomic depression 

 is a number not far removed from 3, the theoret- 

 ical value calculated from Van't Hoff's formula. 

 Assuming the truth of Raoult's generalization, 

 that the depression produced by a molecular 

 proportion of any substance in the solidifying 

 point of the same solvent is the same whatever 

 the substance, it would therefore seem probable 

 that the molecules of most metals are of the 

 same type, Mn., when n is the number of atoms in 

 the molecule ; and if it be supposed that the 



molecules of zinc, for example, when dissolved 

 in tin are monatomic, as in the gaseous state, it 

 would follow that n is unity in the case of many 

 other metals. In the case of aluminum, the 

 atomic depression is so nearly half the average 

 value that it seems probable that the molecule 

 is diatomic. Indium resembles aluminum in 

 producing an abnormally low depression, and 

 the value for mercury is also distinctly Jow. 



The atomic weight of gold has been estimated 

 by Prof. J. W. Mallet in seven series of experi- 

 ments, the mean of which gives 196-910. Throw- 

 ing out three of the series as less entitled to confi- 

 dence than the others, the mean given by the 

 remaining four series is 196-796. Again, taking 

 the first three series, in which auric chloride and 

 bromide were examined, as more comparable 

 with the results obtained by Kriiss and Thorpe 

 and Laurie, the mean is 196-762 The result 

 agrees well with the place occupied by gold in 

 Mendeleef's periodic classification ; and, as 

 regards the hypothesis of Prout, either of the 

 means approaches closely to the integer 197. The 

 work, however, furnishes evidence to the author 

 that not all inherent defects of method have been 

 eliminated. 



To determine the atomic weight of magnesium, 

 W. M. Burton and L. D. Vorce prepared the ni- 

 trate of a weighted portion of the distiljed metal, 

 and ignited it to the oxide. The result of the 

 experiment gave (0=16) Mg=24-287. The au- 

 thor also studied the crystals of the metal, which 

 indicated a closer relation to beryllium than to 

 zinc. 



The atomic weight of bismuth has been deter- 

 mined by Alex. Classen, 0=16, as 208-89830. 



Chemical Analyses. In Dr. GK H. Bailey's 

 and J. C. Cain's method of quantitative analysis 

 by weighing precipitates suspended in liquids, 

 the operations of filtering and washing are done 

 away with. The specific gravity of the precipi- 

 tate having been determined, it is weighed, to- 

 gether with the supernatant liquid, in a specially 

 constructed measuring flask. The specific grav- 

 ity of the supernatant liquid can be readily de- 

 termined, and hence the weight of the precipitate 

 calculated. The method is rapid, and gives re- 

 sults of sufficient accuracy for many technical 

 purposes. 



The analysis of seeds and plants is usually 

 accompanied by a large percentage residue of un- 

 determined matter, the mass of which, excluding 

 a few imperfectly understood albumens, is usually 

 designated as nitrogen-free extract matter. Prof. 

 E. Schulze and Dr. E. Steiger found in the mat- 

 ter of this class in the seeds of Lupinus luteus 

 an insoluble carbohydrate which yielded a sugar 

 named paragaladin that exhibited the proper- 

 ties of galactose. Mr. W. Maxwell found in the 

 residues of Faba vulgaris, Vicia sativa, and 

 Pisum sativum, matters convertible into sugar, 

 usually galactose. Other carbohydrates, in ad- 

 dition to the galactose-yielding body, appear to 

 be contained in the seeds. The relative amounts 

 of the insoluble carbohydrate residu.es and the 

 proportions of galactose-convertible substance 

 contained in them varied in the different species 

 of legumes. The main result of the researches 

 is the finding of a more intelligible and scientific 

 expression for all that portion of the constituent 

 matter of seeds which has hitherto been regarded 



