CHEMISTRY. (CHEMICAL PHYSICS.) 



131 



of iron, John Parry shows that the theory of 

 M6OU8 solution may be applicable to the solu- 

 tion of carbon in molten, semifluid, or merely 

 heated iron, apart from possible cases of dissoci- 

 :iti"ii and chemical combination. Solution, he 

 MIVS, is simply the even distribution of one body 

 In another, or such distribution as that of per- 

 iimifiitlv gaseous matter through space. It may 

 be urged that the theory is not applicable to 

 semifluid or merely heated iron. No definite 

 lint- can, however, be drawn; it is obvious that 

 tin- different grades of temperature are simply 

 approximations, more or less, to the ideal fluid 

 condition. 



Of the two theories on which the process of 

 dyeing has been explained, one the mechanical 

 view regards the process as a simple absorption, 

 similar to that by which animal charcoal takes 

 up gases and liquids and retains them in its 

 pores ; while the other theory traces the effects 

 to definite combinations. Neither of these theo- 

 ries being wholly satisfactory, M. Witt has put 

 forward a hypothesis in which he assimilates 

 tinctorial operations to the phenomena of solu- 

 tion, or to combination in indefinite proportions. 

 He maintains that the coloring matter is dis- 

 solved in the fiber, which becomes dyed only if 

 its affinity for the dye is greater than that of 

 the previous solvent. If the solvent powers of 

 the fiber and of the water are approximately 

 equal a kjnd of equilibrium is established, and 

 the dye does not become completely exhausted. 

 If the solvent power of the fiber is less than that 

 of the water there is no dyeing. In this case the 

 solvent power of the water may be decreased by 

 adding sodium chloride, or sulphate, etc. ; or the 

 solvent power of the fiber may be heightened, 

 for example, by chloring wool, or by depositing 

 sulphur upon it, or by mercurizing cotton. 



The origin of color and fluorescence has been 

 discussed in the English Chemical Society by 

 \V. N. Hartley and H. E. Armstrong. Mr. Hart- 

 ley assumes that it can not be stated in general 

 terms that color is due to special methods of 

 atomic arrangement; but the statement may be 

 applied in a restricted sense to certain organic 

 compounds, especially to those included in the 

 class to which organic dyes belong. The author 

 points out that all organic coloring matters are 

 emlothermic compounds, and considers this to 

 be the physical cause of what Armstrong terms 

 " reactivity," or " high-potential." It is shown 

 that anthracene is not colorless, but has a true 

 greenish-yellow color in addition to its fluores- 

 cence. The conclusions are drawn froHfcthe au- 

 thor's experiments on fluorescence that alcoholic 

 solutions of quinine exhibit a beautiful, bright 

 violet fluorescence ; that hydrochloric acid is not 

 fluorescent ; that quinine hydrochloride and 

 chloroform are feebly fluorescent, but without 

 distinct color; that both hydrochloric acid and 

 chloroform can extinguish those rays which are 

 the cause of fluorescence in quinine ; that some 

 alkaloids may be recognized by the degree and 

 color of their fluorescence ; that normal alcohols 

 of the ethylic series and the fatty acids are fluo- 

 rescent ; that glycerol has a bright fluorescence ; 

 that benzene has a pale blue, azobenzene a green- 

 ish-blue fluorescence; that rock-crystal has a 

 pale bluish-violet, flint glass a strong blue, and 

 crown glass a very brilliant blue fluorescence ; 



and that substances which are not fluorescent in 

 strong solutions may become so on dilution, par- 

 ticularly if they exert a very powerful absorp- 

 tion of the ultraviolet or invisible spectrum. 

 Mr. Armstrong holds that in those cases in which 

 the constitution is fairly well established, col- 

 ored substances are all of one type. From this 

 basis he starts to inquire whether all colored 

 organic substances are not similar in type. 



G. Hinrichs considers that the researches of 

 an entire century have established the fact that 

 if we take O = 1C, the atomic weights of almost 

 all the elements border very closely upon whole 

 numbers; for others, such as copper ana chlorine, 

 the value is close upon a whole number and a 

 half. " We may affirm," he says, " that the most 

 precise determinations of all the elements are ex- 

 actly what they ought to be if all the elements 

 had been formed from a single primitive sub- 

 stance." 



Chemical Physics. Liquid oxygen, as it ap- 

 pears in Prof. Dewar's experiments, is a non- 

 conductor of electricity, and is a high insulator. 

 The spectrum of the spark taken in the liquid is 

 a continuous one, showing all the absorption 

 bands. The lines A and B of the solar spectrum 

 are due to oxygen, and came out stronglv when 

 the liquid was interposed in the path of the rays 

 from the electric lamp. Both gaseous and liquid 

 oxygen have substantially the same absorption 

 spectra. This is a very noteworthy conclusion, 

 considering that no compound of oxygen, so far 

 as is known, gives the absorption spectrum of 

 oxygen. The persistency of the absorption spec- 

 trum through the stages of gaseous condensation 

 toward complete liquidity implies a considerable 

 persistency of molecular constitution. When 

 the evaporation of liquid oxygen is accelerated 

 by the action of a high expansion pump, and an 

 open test tube is inserted into it, the tube begins 

 to fill up with liquid atmospheric air, produced 

 at the ordinary barometric pressure. In his lec- 

 ture at the Royal Institution Prof. Dewar took 

 a cup made of rock salt and put in it some liquid 

 oxygen. The liquid did not wet rock salt, but 

 remained in a spheroidal state. The cup and its 

 contents were placed between and a little below 

 the poles of an electro-magnet. Whenever the 

 circuit was completed, the liquid oxygen rose 

 from the cup and connected the two poles. Then 

 it boiled away, sometimes more on one pole than 

 on the other, and when the circuit was broken it 

 fell off the pole in drops back into the cup. It 

 was also shown that the magnet would draw 

 up liquid oxygen out of a tube. A test tube 

 containing liquid oxygen, when placed in the 

 Hughes balance, produced no disturbing effect. 

 The magnetic moment of liquid oxygen is about 

 1.000 when the magnetic moment of iron is taken 

 as 1,000,000. On cooling, some bodies increased 

 in magnetic power. Cotton wool moistened with 

 liquid oxygen was strongly attracted by the 

 magnet, and the liquid oxygen was sucked out 

 of it on to the poles. A crystal of ferrous sul- 

 phate, similarly cooled, stuck to one of the poles. 

 Fluorine is so much like oxygen in its properties 

 that the author ventures to predict that it will 

 turn out to be a magnetic gas. Nitrogen liquefies 

 at a lower temperature than oxygen, and one 

 would naturally expect the oxygen to come down 

 before the nitrogen when air is liquefied, but 



