468 Scientific Intelligence. 



lead chloride were mixed in a glass flask of 200^*^ capacity. It was 

 found that lead formate and lead nitrate act in a similar way to 

 the chloride, when mixed with potassium iodide, while lead sul- 

 phate reacts much more slowly, although exposed to the air, and 

 the carbonate and oxide react very slowly indeed. 



When mercuric chloride and potassium iodide were treated in 

 exactly the same way as has been described, a strong coloration 

 was produced on mixing, but by drying with specially prepared 

 phosphorus pentoxide, the mixture obtained has been kept for some 

 months without change. Mercuric cyanide showed no reaction 

 with potassium iodide, while mercuric chloride and potassium 

 chroraate reacted very slowly, although exposed to the air. 



The author believes that there is no reason for thinking that 

 the reactions take place in any way essentially different from sim- 

 ilar reactions in solution, except in their slowness. He observes 

 that mercuric chloride, which is ionized but slightly in solution, 

 appears to react more rapidly than the readily ionized lead chlor- 

 ide; hence it appears that ionization cannot be the cause of the 

 difference, and the conclusion is reached that the specitic reaction 

 velocity seems to be the real determining factor. — Chem. JVews, 

 Ixxxviii, 197. h. l. w. 



3. T/ie Determination of Argon in the Atmo8phere. — Moissan 

 has determined the amount of argon in more than twenty samples 

 of air from many different localities. The oxygen and nitrogen 

 of the air were absorbed by hot mixtures of lime and metallic 

 magnesium, and the last traces of these gases, as well as of 

 hydrogen, were removed by the action of hot metallic calcium 

 which this investigator has succeeded in preparing in a state of 

 great purity. The description of the method of analysis indi- 

 cates that the results are very exact. With the exception of a 

 single analysis, where 0*9492 per cent of argon was found in a 

 sample of air from the Atlantic Ocean, the results are very con- 

 cordant, and show that the amount of argon in the air is very 

 constant, whether taken on land or sea, or at high or low alti- 

 tudes. For instance, the percentage of argon found in another 

 Atlantic Ocean sample was 0'9318; two from Paris, 0-933'7 and 

 0-9319; from London, 0*9325; from Berlin, 0*9323; two from the 

 summit of Mt. Blanc, 0*9352 and 0*9327; from St. Petersburg, 

 0-9329; from Moscow, 0*9323; from the summit of Mt. Pelee, 

 0*9366; from the Gulf of Naples, 0*9326; and from Venice, 

 0*9357. The author sums up by saying that samples of air col- 

 lected in the interior of continents at altitudes from to 5800™ 

 show in 100°° an amount of argon which varies fl'om 0*932 to 

 0*935°°, while samples of air from the surface of different seas 

 show in general a slightly larger amount of argon but are also 

 very constant except in the case of a single sample. The author 

 states also that these researches have confirmed the important 

 views of Dumas and Boussingault concerning the constancy in 

 com^Dosition of the terrestrial atmosphere. — Comptes Mendus, 

 cxxxvii, 600. H. L. w. 



