460 Scientific Intelligence. 



5. The Separation of Tungsten Trioxide from Molybdenum 

 Trioxide. — M. J. Rttegenberg and Edgar F. Smith describe a 

 method of separation for the oxides mentioned in the title. It is 

 based upon the fact that tungstic acid is insoluble in concentrated 

 or dilute sulphuric acid, hot or cold, whereas molybdenum trioxide 

 is very easily and rapidly dissolved. Upon trial it was found 

 that sulphuric acid of specific gravity 1*378 was well suited for 

 the purpose. Test analyses were made by mixing about 1 or 2 

 grams of molybdic anhydride with varying quantities of tungstic 

 anhydride and digesting with 25 cc of warm sulphuric acid of the 

 strength mentioned above for a few minutes, then filtering, wash- 

 ing with water containing sulphuric acid, and weighing the 

 tungstic acid. The results of six analyses were extremely sharp. 

 The authors found also that tungstic acid may be separated from 

 ferric hydroxide in precisely the same way. — Jour. Am. Chem. 

 Soc., xxii, 772. h. l. w. 



6. On Radio-active Barium and Polonium. — When concen- 

 trated uranium nitrate solution is mixed with a little sulphuric 

 acid, then with a solution of a barium salt, care being taken that 

 sufficient barium salt is not added to cause a precipitate, and 

 finally diluted with water, a strongly radio-active precipitate of 

 barium sulphate is obtained. When this sulphate is converted 

 into a soluble barium salt and this is treated with ammonium 

 hydroxide, a small amount of precipitate is obtained which is 

 even more strongly radio-active than the original sulphate ; but 

 when the barium is subsequently converted into carbonate, it has 

 completely lost its activity. The radio-activity is probably due 

 to small quantities of radium, or more probably of actinium. 

 Polonium preparations obtained from lead chloride from uranium 

 residues have proved to consist of bismuth hydroxide, which, 

 either in this form or as oxychlorides exhibits strong activity. — 

 jBerichte, xxxiii, 1665. Jour. Chem. Soc, Ixxviii, 480. 



7. Lecture Experiments Illustrating the Electrolytic Dissocia- 

 tion Theory and the Laws of the Velocity and Equilibrium of 

 Chemical Change. — A. A. Notes and A. A. Blanchard have 

 published a description of seventeen experiments which were 

 originally devised as an accompaniment to an extended course of 

 lectures on theoretical chemistry. Most of the principles illus- 

 trated are of such fundamental importance that they should soon 

 be generally introduced into elementary lecture courses on inor- 

 ganic and analytical chemistry. The experiments are devised 

 with much skill and will furnish very striking illustrations to the 

 audience. They are described in great detail, so that they may 

 be readily performed by the lecturer, and the principles illustrated 

 are clearly stated in each case. It is certain that this series of 

 experiments will be of great assistance to teachers of theoretical 

 chemistry, and it will doubtless serve to hasten the introduction 

 of instruction in the principles of chemical equilibrium and of 

 electrolytic dissociation into elementary courses. — Jour. Am. 

 Chem. Soc, xxii, 726. h. l. w. 



