PHYSICS. 345 



tbe viscosity itself are incomplete for this phenomenon. (Proc. Am. 

 Acad., May, 1885; Pbil. Mag., March, 18S6, V, xxi, 199.) 



Krffiwitch has communicated to the Russian Physico-Chemical Soci- 

 ety a paper on the relation between tbe elasticity and density of the 

 air in a rarefied condition. His experiments on the velocity of sound 

 show that at a temperature of 17.5 this velocity decreased Irom 3^0 

 meters at a pressure of 761 millimeters to 171 meters at a pressure of 

 2.6 millimeters. At a pressure of 280 millimeters tbe velocity is about 

 the same as at the mean air pressure, but it diminishes rapidly below 

 280 millimeters. He concludes that below this pressure gases do not 

 obey the law of Boyle-Marriotte. (Science, February, 1886, yii, 161.) 



Certain irregularities in the experiments made by Bohr on the loosely 

 combined oxygen in oxyhaemoglobin led him to investigate the accuracy 

 with which, under low pressures, this gas follows Boyle's law. The re- 

 sults of this investigation seem to him to prove indisputably- that oxy- 

 gen varies considerably from the law under these conditions. In the 

 course of the experiments the unexpected phenomenon was met with 

 that the curve which expresses the relation between volume and tension 

 exhibits a stronglj^ marked discontinuity at a certain tension, which 

 seems to suggest that there is here an alteration in the molecular com- 

 position of oxygen. He finds that at a temperature between 11° and 

 140 oxygen deviates from Boyle's law within the limits in question. 

 The relation between volume and pressure, when the latter is greater 

 than 0.70 millimeter, being expressed approximately by the formula 

 {p-\-OAOd)v=l-: while for pressures below this value the formula becomes 

 [2J-\-0.070)v=k. Moreover, if the pressure sinks below 0.70 millimeter 

 oxygen undergoes a change of state. By raising the pressure above 

 0.70 millimeter it may be restored to its original condition. ( Wied. Ann., 

 1886, No. 3; Phil. Mag., April, 1886, V, xxi, 368.) 



A paper on the properties of matter in the gaseous and liquid states 

 under various conditions of temperature and pressure, by the late 

 Thomas Andrews, has been presented to the Eoyal Society by its presi- 

 dent. Professor Stokes. The following are its conclusions: (1) The law 

 of gaseous mixtures, as enunciated by Dalton, is largely deviated from 

 in the case of mixtures of nitrogen and carbonic acid at high pressures, 

 and is probably only strictly true when ap[)lied to mixtures of gases in 

 the so called perfect state; (2) the critical point of temperature is low- 

 ered by admixture with a permanen^t gas ; (3) when carbonic acid gas 

 and nitrogen diffuse into each other at high pressures the volume of 

 the mixture is increased ; (4) in a mixture of liquid carbonic acid and 

 nitrogen at temperatures not greatly below the critical point, the liquid 

 surface loses its curvature and is effaced by the application of pressure 

 alone, while at lower temperatures the nitrogen is absorbed in the ordi- 

 nary way and the curvature of the liquid surface is preserved so long 

 as any portion of the gas is visible. (jSTature, April, 1886, xxxiii, 550.) 



Winkelmanu proposes to show the velocity of diffusion in diilerent 



