440 SCIENTIFIC EECOED FOR 1884. 



replacements = 2H, O = 3H, and CI = 7H; so that from the formula 

 of a body the value of N can be deduced, and thus the surface tension 

 at the boiliug point calculated. {Liebig's Annalen, March, 1884, ccxxiii, 

 47 ; N attire, October, 1884, xxx, 618.) 



Krouchkoll has observed that isolating liquids, such as carbon disul- 

 phide, ether, and turpentine, not miscible with water^ acquire a conduc- 

 tivity when in contact with this liquid. He then made an investiga- 

 tion to ascertain whether the capillary constant at the surface of con- 

 tact between one of these liquids and water varied under the action of 

 an electro motive force. The results of his experiments jirove that 

 this variation actually takes place, and that it is in the same direction 

 as in the case of the surface of separation between water and mercury. 

 [J. Phys., II, III, 303, July, 1884.) 



Wroblewski's experiments on th.e direct liquefaction of oxygen by 

 compression gave for the density of the liquid only a superior limit, given 

 as 0.94. By observing that the tension of oxygen at — 13(P is neiir that 

 of carbon dioxide and nitrogen monoxide at 0°, knowing that the den- 

 sity of liquid CO2 is 0.9471 and of N2O is 0.9370, the author has calcu- 

 lated the density of liquid oxygen to be 0.899. This agrees well with 

 Cailletet and Hautefeuille's results, who obtained, by compressing a mixt- 

 ure of 7 volumes of CO2 and 1 of O, the value 0.89 at —13° C. and 300 at- 

 mospheres pressure ; and from a mixture of l^iO and O, the value 0.94 

 at —23° and 300 atmospheres. The value 0.899 also agrees with the press- 

 ures observed by Pictet in his experiments on the compression of oxy- 

 gen. {Wied. Ann., xx, 80; J. Phys., II, iii, 03, February, 18S5.) 



Bender has investigated the law of density of saline solutions by 

 comparing together solutions containing, for a given volume, a given 

 number of equivalents of various salts. Using, for example, chlorides, 

 he finds that the difference between the density of the solution of any 

 salt whatever and that of a solution of sal ammoniac is proportional to 

 the number of equivalents contained in the solution, provided always 

 that this number does not exceed four. The law extends to other radi- 

 cals besides chlorine, so that the density of any saline solution what- 

 ever may be represented by the formula — 



^^= (<7m) KH4C1 + fi {1n^, + Wis) 

 in which /« is the number of equivalents of the salt contained in the so- 

 lution and mx, and m^ the moduli of the metal and of the acid radical. 

 These moduli have been experimentally determined by the author, and 

 from these the density of any normal solution whatever may be calcu- 

 lated. ( Wied. Ann., xx, 560 J J. Phys., May, 1884, II, iii, 221.) 



Mendelejeff has communicated to the Kussian Chemical Society a 

 paper on salt solutions. It would be easy to prove, he says, with the 

 data of Gerlach, Marignac, Cremers, and Schiff, that the volume of a 

 given amount of a salt in its solutions (of a molecule, for instance) va- 

 ries with the variations of temperature and the degree of concentration 

 of the solutions. It increases with both of these values; and it might 



