CHEMISTRY. 



water at 15 0. corresponds with a solution of 

 potassium chloride also containing a gramme- 

 molecule, or a barium-chloride solution con- 

 taining half a gramme-molecule, barium being 

 divalent ; corresponding with these are also a 

 solution of ammonium chloride containing 

 gramme-molecule, and a lithium-chloride solu- 

 tion in which f gramme- molecule is dissolved in 

 a litre of water. With respect to electrical con- 

 ductivity, the following also correspond: Solu- 

 tions of NaCl, LiOl, and $ (BaCU), each con- 

 taining n gramme-molecules; and of KC1 and 

 NtUCl, each containing n gramme-molecules 

 per litre. 



Chemical Physics. A close relation has been 

 found by Carnelly and Thomson to exist between 

 the solubility and the fusibility of isomeric car- 

 bon compounds. Pictet had observed that the 

 lower the melting-point of a solid, the longer 

 are the oscillations of its molecules, so that the 

 product of the melting-point, measured from 

 the absolute zero, by the oscillation, is con- 

 stant. Hence, the author's reason, of two 

 isomers, the one with the lower melting-point 

 will, at any temperature below this point, have 

 its molecules moving with oscillations of great- 

 er amplitude than the one with the higher 

 melting-point; and being in less stable condi- 

 tion, they will be more readily separated from 

 their fellows. Solution also being a sort of 

 loosening process to the molecules, should fol- 

 low a similar rule. Hence, it is concluded, 

 the order of fusibility is the order of solu- 

 bility; and in any series of isomeric acids, not 

 only is the order of solubility of the acids 

 themselves the same as the order of fusibility, 

 but the same order of solubility extends to all 

 the salts of these several acids. The authors 

 find that for any series of isomeric compounds 

 the order of solubility is the same whatever be 

 the nature of the solvent; and that the ratio 

 of the solubilities of the two isomerides in any 

 given solvent is very nearly constant, and is 

 therefore independent of the nature of the 

 solvent. 



In his earlier experiments on the union of 

 bodies by pressure (see "Annual Cyclopaedia "for 

 1883), Spring made use of simple substances ; in 

 his later work compound bodies are used. Mixt- 

 ures of dry, pure, precipitated barium sulphate 

 and sodium carbonate were subjected to the 

 influence of a pressure of six thousand atmos- 

 pheres under various conditions of temperature 

 and duration of contact. It was found that the 

 amount of barium carbonate produced by this 

 action increases with the number of times the 

 mixture is compressed. After a single com- 

 pression the amount was about one per cent. 

 If the solid block produced by this compression 

 is ground into fine bits and again subjected to 

 the same pressure, and the process repeated a 

 second time, about five per cent, of the barium 

 carbonate results. A sixth compression yielded 

 nine per cent, of the product. If the little 

 blocks produced by one, three, and six com- 

 pressions are left to themselves for some days 



and then examined, it is found that, up to a 

 certain limit, reached in about fourteen days, 

 the amount of barium carbonate formed in- 

 creases with the length of time during which 

 the blocks have been exposed. When the re- 

 actions are reversed that is, when sodium 

 sulphate and barium carbonate are mixed and 

 subjected to pressure, a part of the barium 

 carbonate, increasing with repetitions of the 

 pressure, passes over into the sulphate. The 

 author regards it as established that matter as- 

 sumes under pressure a condition relative to 

 the volume it is obliged to occupy; and that 

 for the solid state, as for the gaseous, there is 

 a critical temperature, above or below which 

 changes by simple pressure are no longer pos- 

 sible. 



Heating a platinum wire nearly to melting in 

 an atmosphere of chlorine, W. R. Hodgkinson 

 observed that the walls of the glass vessel were 

 covered with a yellow deposit that proved 

 to be platinons chloride, while the les* heated 

 part of the wire was incrusted with tine long 

 crystals of platinum, and a lambent flame was 

 seen playing about the wire. With bromine 

 instead of chlorine, less of the salt was formed, 

 but the flame was more pronounced; with 

 chloride of bromine, both phenomena were in- 

 tensified ; with iodine the action was weak ; but 

 with chlorine and iodine it was very vigorous. 

 With phosphoric chloride, the phosphorus 

 united with the platinum and melted it; and 

 witii silicon fluoride the wire was covered with 

 crystals supposed to be of silicon. 



The cause of the ejection of solid particles 

 from platinum and palladium when glowing 

 under the influence of the electric current, with 

 formation of incrustations upon the glass tube 

 surrounding the wire, has been investigated by 

 Dr. Alfred Berliner. It proves to be produced 

 by the escape of gases occluded within the 

 metal, carrying off particles of the substance 

 with them. 



The vapor-density of sulphur has been rede- 

 termined by Dr. Biltz. Previous experiments 

 made at a limited range of temperature not far 

 from its boiling-point, indicated a composition 

 of this element of six atoms to the molecule. 

 The later experiments by Dr. Church, now con- 

 firmed by Dr. Biltz, made at higher tempera- 

 tures and showing a regular decrease of vapor- 

 density aw the temperature rises, give the nor- 

 mal constitution of two atoms to the molecule, 

 which is reached at 860 C., as alone standing 

 the test of intervals of temperature. 



Experiments upon the vapor-density of ferric 

 chloride by Drs. Griinewald and Victor Meyer 

 for the purpose of determining its molecular 

 formula, give as a result FeCl 3 as the true 

 symbol, instead of FeaCU. The result brings 

 the formula of this salt into harmony with 

 those of the corresponding salts of aluminum, 

 A1C1 3 , and Indium, InCl 3 . It follows that the 

 former view as to the tetrad nature of iron 

 must be laid aside. 



Thomson and Threlfal have found that on 



