238 Scientific Intelligence. 



alloy was sensibly less than that of the merely mixed metals. 

 Incidentally it was found that the equation Cl 2 .Aq= 2,600 

 (Tbomsen's " Thermochemische Untersuchungen ") is erroneous 

 and, on inquiry, Professor Thomsen gave a corrected value, 4,8*70. 

 The author finds Cl 2 . Aq = 4,9*70. 



The most suitable solvents of the alloys are — 



(a.) Mixture of ammonium chloride and ferric chloride solu- 

 tions. 



(b.) Mixture of ammonium chloride and cupric chloride solu- 

 tions. 



The chemical actions involved are simple reductions, and no 

 gases are evolved. 



Two series of experiments made on twenty-one alloys yielded 

 very concordant results. They show that heat is evolved in the 

 formation of every alloy of copper and zinc yet tested. A 

 sharply defined maximum heat of formation is fouud in the alloy 

 containing 32 per cent of copper, i. e., corresponding to the 

 formula CuZn 2 . It amounts to 52*5 calories per gram of alloy or 

 10,143 calories per gram-molecule. There is some evidence of a 

 sub-maximum in the alloy nearly corresponding to CuZn. From 

 these points there is a steady decrease in the heat of formation, 

 both in the case of alloys containing less than 32 per cent of cop- 

 per as the amount of copper decreases, and also in the case of 

 those containing more than 50 per cent of copper as the quantity 

 of copper increases. 



The results, in general, confirm the existence of intermetallic 

 compounds, and the values obtained are in accordance with those 

 demanded by Lord Kelvin's calculation of the molecular dimen- 

 sions of copper and zinc. 



10. On the decrement of electrical oscillations in charging 

 co?idensers. — This paper is the work of two authors. A. F. Sun- 

 dell has worked out the theory and Hj. Tallquist the experi- 

 mental appliances. It was found that after a relatively short 

 time reckoned from the beginning of the charging the capacity 

 of a mica condenser reached the same value under oscillatory 

 charges as under direct charges. The method also give a means 

 of determining self-induction. — Ann. der Physik., No. 1, 1901, 

 pp. 72-98. j. t. 



11. Effect of a magnetic field on the discharges through a gas. — 

 De. R. S. Willons concludes from his experiments that at pres- 

 sures below '5 mra the magnetic field decreased the electric force 

 near the cathode ; this decrease depended upon the strength of 

 the field and the current. At higher pressures the magnet 

 increased the electric force. If the magnet caused the column 

 to striate it also caused the electric force to show periodic stria- 

 tions. The magnet generally caused the electric force at the 

 anode to increase. — Phil. Mag., pp. 250-260, Feb. 1901. j. t. 



12. Conductivity produced in gases by the motion of negatively 

 charged ions. — Professor Townsend, of Oxford, England, had 

 previously shown that negatively charged ions moving through 



