378 v Scientific Intelligence. 



Effective rigidity can be imparted to the ether by the apparatus 

 designed by Trouton and used by Burgess. It consisted of a 

 vertical, copper U-tube strong enough to withstand an internal 

 pressure of more than loo atmospheres in excess over the outside 

 atmospheric pressure. One of the parallel branches of the tube 

 was permanently connected with a pressure gauge, and the upper 

 ends of both branches were provided with stopcocks and inlet 

 tubes. In charging the apparatus the first step was to introduce 

 enough sugar solution to half-fill the tube. Then ether was 

 sucked into the branch which was not directly associated with 

 the gauge, and the cock closed. Next, air was pumped into the 

 other branch of the U-tube until the gauge registered the desired 

 pressure, after which the second cock was closed. After sufficient 

 time had elapsed for the ether to take up its full complement of 

 water from the solution, the cock of the branch containing the 

 ether was opened, thus allowing the compressed air in the other 

 branch to force the ether out into the auxiliary testing tubes. 

 The water content of the ether was determined by passing the 

 moist ether, as vapor, through calcium chloride drying tubes 

 which were maintained at 40° C. " This was sufficiently warm 

 to prevent ether condensing in the tubes, and yet was found not 

 to be too high for substantially absorbing all the water." This 

 entire process was repeated at different pressures, so that all the 

 necessary data were obtained for plotting a curve having for the 

 abscissas of its points, pressures in atmospheres, and for the ordi- 

 nates, percentages of water absorbed by the ether. For a con- 

 centration of 600 grams of sugar per liter of solution the aforesaid 

 percentages increased from 0-939 to 1*143 as the pressure changed 

 from 1 atmosphere to 110*5 atmospheres. The curve is somewhat 

 convex towards the pressure axis. At about 79 atmospheres the 

 per cent of water taken from the sugar solution by the ether was 

 read off from the curve as 1*055, which is numerically the same 

 as for the absorption of water by ether at a pressure of one 

 atmosphere. Consequently, the osmotic pressure equals 79 atmos- 

 pheres. Interpolating for the given concentration from the 

 curves of Lord Berkeley and Mr. Hartley, the osmotic pressure 

 as determined by the ferrocyanide of copper method was found 

 by Trouton to be SI atmospheres. The agreement is quite satis- 

 factory in view of the fact that Trouton has not yet attempted to 

 perfect his method, and to take into account all necessary correc- 

 tions for variations in temperature, in concentration, etc. — Pro- 

 ceedings .Roy. iSoc, lxxxvi, p. 149, Jan., 1912. h. s. u. 



8. Note on the Monatomicity of Neon, Krypton and Xenon. — 

 Having at his disposal relatively large quantities of pure neon, 

 krypton and xenon, and being of the opinion that the monato- 

 micity of these gases had been taken for granted on somewhat 

 insufficient evidence, Sir William Ramsay has quite recently 

 determined y, the ratio of the specific heat at constant pressure 

 to that at constant volume, for each of these gases. The appa- 

 ratus used was of the same type as the one described in the mono- 



