110 



CHEMISTKY. 



pound could be in tlie slightest degree electro- 

 lyzed by an exceedingly intense current. Un- 

 til all such bodies as were open to experiment 

 had been cautiously and strenuously examined, 

 they were unable to say whether there was a 

 hard and fast line between the modes of con- 

 duction, or in what manner the graduation 

 from one to the other occurred. Another im- 

 portant question was whether the electric cur- 

 rent actually decomposed or tore asunder the 

 molecules of the liquid through which it passed, 

 or whether it found a certain number of those 

 torn asunder or dissociated into their atoms by 

 chemical, or at any rate, non-electrical, means, 

 and that these loose and wandering atoms sub- 

 mitted to the guiding tendency of the electric 

 slope, and joined one or the other of two pro- 

 cessions toward either electrode, only offering 

 resistance when brought into immediate prox- 

 imity with the electrode. 



Dr. Hans Molisch proposes as more delicate 

 and speedy tests than have hitherto been used 

 for distinguishing between animal and vegeta- 

 ble fibers, two new sugar reactions which he 

 has discovered and described in full in the 

 " Transactions of the Imperial Academy of Sci- 

 ences in Vienna. 1 ' They are, the production by 

 all sugars witli alpha naphthol of a deep-violet 

 coloration, and with thymol of a cinnabar-ru- 

 by-carmine - red, flocculent precipitate. The 

 same reactions are given indirectly by the car- 

 bohydrates and glucosides, from which sugar 

 is formed after treatment with sulphuric acid. 

 Plant-fibers contain sugar or the substances 

 convertible into sugar, and give the sugar-tests ; 

 animal fibers do not. A few silks give a weak, 

 transient reaction, but it is so slight and con- 

 tinues for so short a time that it need not de- 

 ceive the careful observer. It is important, 

 however, in applying the test, to remove all 

 foreign vegetable matter that may be acciden- 

 tally present, or left in the finishing. This 

 may be done by boiling and washing. 



Lecoq de Boisbaudran having asserted, con- 

 tradictory to Becquerel's conclusions, that cal- 

 cined alumina does not give a trace of fluores- 

 cence when submitted to the electric discharge 

 in vacuo, and that the red fluorescence of alumi- 

 na seems to depend upon the presence of chro- 

 mium, Becquerel has repeated his experiments, 

 using for the purpose substances furnished by 

 De Boisbaudran himself, and finds his previous 

 conclusions confirmed. The fragments of albu- 

 mina, when excited by the light of the elec- 

 tric arc, emitted a red light, which, however, 

 was much weaker than that given out, under 

 the same circumstances, by alumina containing 

 chromium. But, after calcination, this alumi- 

 na became quite as luminous as alumina con- 

 taining chromium, and of the same color. 

 "With alumina prepared by himself, the light 

 emitted was the characteristic red light. The 

 addition of chromium, then, does not change 

 the color of the phosphorescent light, but sim- 

 ply increases its intensity. Becquerel calls at- 

 tention to the difference in the luminous phe- 



nomena according as they are produced by the 

 electric light in the phosphoroscope or by the 

 electric discharge in t>acuo ; the former effects 

 being simple, but not obtainable with all bod- 

 ies. Crookes has also examined this subject, 

 w ; th a view of clearing up the discrepancies 

 between the two observers. His results gen- 

 erally corroborate Becquerel's observations. 



A. Percy Smith says, in a note on " The 

 Identification of Alkaloids and other Crystal- 

 line Bodies by the Aid of the Microscope," that 

 the number of cases in which such substances 

 can be identified by this instrument alone is 

 extremely limited ; but, as a test of purity, mi- 

 croscopic investigation has a very wide appli- 

 cation. When we are dealing with a substance 

 that, when pure, crystallizes in a definite form 

 from any particular solvent, it is manifest that 

 any departure from that form would lead to 

 the suspicion of adulteration. Again, if we 

 take such a substance as bark or opium, it is 

 quite possible to distinguish from one another 

 the various alkaloids which it contains. Be- 

 sides the form assumed by the free base, it is of 

 importance to convert it into a salt, as there is 

 frequently a marked departure in the form of 

 the crystals of the latter from that of the base. 

 Some experience is necessary in eoin the 



most suitable solvent from which tot.j n >a]lize 

 an alkaloid, as the duration of the evaporation 

 may have a marked effect upon the form of 

 the crystals. In some cases, evaporation may 

 be accelerated by the aid of heat ; in others, 

 such a proceeding is fatal to success. The ad- 

 dition of alcohol to ether, and of water to al- 

 cohol, appears to be the best means of retard- 

 ing the process when necessary. The author 

 always employs polarized light by which to 

 view the crystals, either with or without the 

 addition of a selenite plate. Here, again, the 

 duration of evaporation has a marked effect, as 

 also does the strength of the solution. If the 

 substance is deposited in a thin film, it may be 

 altogether invisible without polarized light. 

 Thick crystals frequently produce color with- 

 out the selenite, and those that are very thick 

 may depolarize without any coloration. This 

 being borne in mind, no difficulty whatever is 

 experienced in practice, as it is easy to compare 

 with an alkaloid of known purity crystallized 

 under the same conditions. 



J. Edward Whitfield has reported upon the 

 analysis of natural borates, in which, instead 

 of the inaccurate methods hitherto in use, boric 

 acid has been determined by a method devised 

 by Dr. F. A. Gorch. The minerals analyzed 

 are Oolemanite, from- California ; Priceite, 

 from Oregon ; TJlexite, from Nevada ; Ludwig- 

 ite, from the Banate, Hungary ; Datolite, from 

 Bergen Hill, N. J. ; Danburite, from New York ; 

 and Axinite, from Cornwall and from Dau- 

 phiny, France. 



Atomic Weights. Prof. Thorpe and Mr. A. P. 

 Laurie have redetermined the atomic weight 

 of gold from a preparation of the double bro- 

 mide of potassium and gold. Taking Stas's 



