Chemistry and Physics. 309 



son has found that metallic iron in the form of " card-teeth " in 

 the presence of 10 per cent sulphuric acid effects this reduction 

 rapidly at ordinary temperatures. At first ferric salts are formed 

 and give the solution a yellow color, but these salts are soon 

 reduced and the solution becomes colorless or slightly green. 

 The reduction requires about one hour at room temperature. 

 The process is applicable to bromates, while perchlorates are not 

 reduced by the operation and hence do not interfere with it. 

 Test-analyses are given which show excellent results, and it 

 appears that the method is a very simple and convenient one. — 

 Amer. Chem. Jour., xxxii, 242. h. l. w. 



4. The Investigation of Double Salts by the Determination of 

 Solubility. — As a continuation of work by the method devised by 

 Professor Foote of the Sheffield Scientific School, Foote and 

 Bristol have found that barium and mercuric chlorides, below 

 17'2°, form the double salt BaCl 2 * 3HgCl 2 * 6H 2 0. Above this 

 temperature no double salt can be crystallized, although there is 

 evidence that combination takes place in solution, because the 

 solubility of each salt is largely increased by the presence of the 

 other. The double salt thus found is a new one. A compound, 

 BaCl 2 * 2HgCl 2 # 2H 2 0, described by Bonsdorf about seventy-five 

 years ago, does not exist, at least at 10"4°. 



Foote has found also that the remarkable double nitrate, 

 2KN0 3 * Ba(N0 3 ) 3 , described a year or two ago by Wallbridge., 

 is a true double salt, capable of forming under a rather wide 

 range of conditions. He has shown also that no double salt is 

 produced by potassium and barium chlorides at 25°, although the 

 combination of chlorides is far more usual that that of fiitrates. 

 — Amer. Chem. Jour., xxxii, 246; 251. h. l. w. 



5. Nitrous Anhydride. — It has been known for a long time that 

 mixtures of the gases NO and N0 2 condense to a blue liquid, and 

 it has been shown by Lunge and Porschnew that at -20° the com- 

 position of the blue liquid formed by saturating liquid N 2 4 with 

 gaseous NO corresponds very closely to the compound N 2 3 , or 

 nitrous anhydride. This blue compound, consequently, has been 

 regarded as nitrous anhydride, but up to the present time it has 

 not been shown that the compound exists in the solid state, nor 

 that it is the only compound of the two gases. Wittorff has 

 recently made fusing-point determination with known mixtures 

 of N 2 4 and NO, and has found that N 2 3 exists in the form of 

 blue crystals which melt at -103°, and that no other compound 

 was formed at the temperatures used in the experiments. — Zeitschr. 

 anorg. Chem. xli, 85. h. l. w. 



6. A Probable Cause of the Yearly Variation of Magnetic 

 Storms and Auroral y* by Sir Norman Lockyer and William 

 J. S. Lockyer. — The ordinary meteorological elements, such as 

 atmospheric pressure, temperature, etc., have a yearly change 



* From the Proceedings of the Eoyal Society of London, lxxiv, 90. 



Am. Jour. Sci. — Fourth Series, Yol. XVIII, STo. 106. — October, 1904. 

 21 



