112 



CHEMISTRY. (CHEMICAL PHYSICS.) 



fluorine gas when examined in a stratum one metre 

 thick. Fluorine thus becomes liquid, according to this 

 experiment, at about 185 C. When the bulb con- 

 taining the liquid fluorine was lifted above the surface 

 of the liquid oxygen, the yellow liquid began to boil 

 with an abundant disengagement of gas having all 

 the energetic reactions of fluorine. Silicon, boron, 

 carbon, sulphur, phosphorus, and reduced iron, 

 cooled in liquid oxygen and then placed in an at- 

 mosphere of fluorine, did not become incandescent. 

 At this low temperature fluorine did not displace 

 iodine from iodides. The chemical energy, how- 

 cv.-r. wns still sufficiently great to decompose ben- 

 zene or oil of turpentine with incandescence. A 

 current of fluorine gas passed into liquid oxygen 

 was observed on some occasions to give a flocculent 

 white precipitate, which quickly settled to the bot- 

 tom, ft possessed the curious property of deflagrat- 

 ing with violence upon any rise of temperature. 

 With freshly prepared liquid air instead^of oxygen, 

 fluorine easily became liquid at 190 C. With 

 liquid' oxygen as a refrigerant, the liquefaction took 

 place at a' temperature corresponding to the evap- 

 oration of the oxygen under a pressure of 437 milli- 

 metres of mercury. From these experiments it re- 

 sults that the boiling point of fluorine is very close to 

 187 C., a number identical with Olszewski's boil- 

 ing point of argon. By causing the liquid oxygen 

 serving as a refrigerant to boil rapidly, a tempera- 

 ture of 210 was reached, at which temperature 

 the liquid fluorine showed no sign of solidifica- 

 tion. Some air which was accidentally admitted 

 was immediately liquefied. In a few moments two 

 distinct layers of liquid were seen ; the upper, color- 

 less layer, consisted of liquid air ; the lower one, of 

 a pale-yellow color, was fluorine. The density of 

 the liquid was determined at 1.14; its capillarity 

 was less than that of liquid oxygen ; it was found 

 to have no absorption spectrum, and is not mag- 

 netic. 



The results of three experiments by J. H. Kastle 

 and W. A. Beatty go to prove that light causes the 

 combination of hydrogen and bromine at 198' C., 

 with an amount of change proportional to the time 

 of exposure. In the dark at 196 C. the combina- 

 tion of the two gases is exceedingly slow, whereas 

 in the sunlight the change is fairly rapid. Certain 

 results that have been obtained would, moreover, 

 seem to indicate that light causes the combination 

 of the two elements even at 100 3 C. ; but further 

 experiments will be necessary to establish this 

 point fully. The results seem to strengthen the 

 analogy existing between chlorine and bromine. 

 The difference in the temperatures necessary to 

 enable the light to cause the combination of these 

 elements with hydrogen is regarded as simply 

 another rough measure of their relative affinities. 



Experiments by W. J. Russell have shown that 

 certain metals have the property of giving off, even 

 at ordinary temperatures, vapor which affects the 

 sensitive photographic plate, that this vapor can 

 be carried along by a current of air, and that it has 

 the power of parsing through thin sheets of such 

 bodies as gelatin, celluloid, collodion, etc. ; in fact, 

 so transparent are these bodies to the vapor that, 

 even after it has passed through them, it is capable 

 of producing dear pictures of the surface of the 

 metal from which it came. Curiously, the most 

 active metals are not the most volatile, and this 

 ami other facts make it evident that much still re- 

 mains to be discovered on this subject. The ex- 

 periments have been extended to active organic 

 substances, and very interesting and various results 

 have been obtained with oils, essential oils, mineral 

 oils, liquors, etc. 



The fact that the luminosity of phosphorus in air 

 is increased by certain gases and inhibited by others 



was investigated by Thomas Graham and later by 

 Joubert, who demonstrated that luminosity and 

 oxidation go hand in hand, and that inhibited 

 phosphorescence could be, as in the case of pure 

 oxygen, resuscitated by a reduction of pressure. 

 The investigation has been extended by II err 

 Centnerzwer to embrace a large number of organic 

 substances ; and it has been found that the specific 

 influence of the substances admits of certain genera! 

 conclusions. Thus it increases in a homologous 

 series as the number of carbon atoms increases ; it, 

 is approximately the same for isomers ; it is in- 

 creased by a double linkage of carbon atoms ; it is 

 not generally affected by the substitution of chlo- 

 rine or bromine for hydrogen ; but is increased in 

 a high degree by the replacement of hydrogen by 

 iodine. The results have, however, not given any 

 clear idea of the mechanism of the process by 

 which the oxidation is suspended. 



In his investigations of the thermal properties of 

 gases and liquids, Prof. Sydney Young determined 

 the vapor pressures and specific volumes of a num- 

 ber of substances both as liquids and as saturated 

 vapor, from low temperatures to their critical 

 points. Twenty-six substances were examined, in- 

 cluding paraffin, benzene and its haloid derivatives, 

 esters, alcohols, and acetic acid, and the data 

 obtained allow of a simple classification in respect 

 to their physical constants. Among other point?, 

 of interest results show that the molecules of the 

 alcohols at moderate temperatures arc polymerized 

 in the liquid state but not in the gaseous, while 

 there is polymerization in both states in the case of 

 acetic acid ; also that the molecules of the alcohols 

 and acetic acid appear to be polymerized to a con- 

 siderable extent at the critical point. Ample proof 

 was obtained in the course of the investigations 

 that the views of Andrews regarding the behavior 

 of a substance in the neighborhood of the critical 

 point are correct, and also that the vapor pressure 

 of a pure substance is independent of the relative 

 volumes of liquid and vapor. 



Having already found that nitrogen and oxygen 

 gases, properly purified, form clear, transparent 

 liquids, Prof. Dewar devised an apparat us for ascer- 

 taining the proportion of any gas in air that is not 

 condensible at 210. under atmospheric pressure or 

 is not soluble in liquid air under the same condi- 

 tions. It was found that 1 part of hydrogen in 

 1,000 of air was just detectable by his method. 

 Ordinary air, containing 4 parts of carbonic acid 

 per 11.000 parts, gave a turbid liquid from the 

 solidification of the carbonic acid, and oxygen con- 

 taining traces of chlorine behaved in a similar 

 manner. 



It is observed by A. Liversidge that when solid 

 carbon dioxide is examined under the microscope 

 it presents along its edges projecting wirelike 

 crystals which have branching filaments issuing 

 from them, apparently at right angles, resembling 

 somewhat the groups of minute crystals seen in 

 crystallized iron, gold, and ammonium chloride. 

 The rapidity with which the carbon dioxide evap- 

 orates makes it difficult to catch the form of the 

 crystals, either by photography or other means. 



The property of producing a beautiful red color- 

 ation with nitro-prussiate of sodium and potash. 

 either with or without the subsequent addition of 

 acetic acid, is shared. Louis Simon has shown, by 

 ordinary ethylic aldehyde with a large number of 

 aldehydic and ketonic bodies ; the addition of ;t 

 few drops of aqueous methylamine and a few 

 drops of dilute nitro-prussiate to a weak solution 

 of ordinary ethylic aldehyde gives a beautiful char- 

 acteristic blue color. 



In a series of experiments made simultaneously 

 by M. and Mme. Vallot at Charaounix (altitude 



