142 



Influence of Atomic Weight. 465 



comparing these weights together, we find, as a general rule 



(to which there are but three exceptions), that the higher the 



boiling-point of the gas when liquid, the greater is the weight 



absorbed by a given volume of charcoal. 



Ano-us Smith (Chem. News, xxxix. p. 77) has recently 



remarked that the weight of several of the elementary gases 



absorbed by 1 volume of charcoal 



(atomic weight) 2 



~~ quantivalence of the element* 



Thus, if the weight of H absorbed be taken as the unit, then 



the weight of absorbed under similar conditions 



16 2 

 = 128= f, 



and the weight of N absorbed 



= 65-3- 



o 



Further experiments in the case of other elementary gases, 



however, are required to confirm this interesting and curious 



relation. 



Compressibility and Expansibility of Liquids. — According to 

 Amagat (Compt. Mend, lxxxv. pp. 27, 139), the compressi- 

 bility of compounds belonging to the same homologous series 

 diminishes regularly as we ascend in the series, or as the 

 boiling-point increases. The introduction of S, CI, or Br into 

 a compound tends to render it less compressible. 



-Kopp has compared together the rates of expansion (as deter- 

 mined by himself and Pierre) of nearly ninety liquids; and he 

 finds, as a general rule (but one to which there are many ex- 

 ceptions), that the most expansible liquids are those which have 

 the lowest boiling-points. In the case of compounds belong- 

 ing to the same homologous series the rate of expansion always 

 diminishes as we ascend the series, and therefore as the boil- 

 ing-point increases. The fatty acids expand less rapidly than 

 any of their ethers, at any rate up to the amy lie ethers ; all 

 data are wanting for the higher ethers. The alcohols expand 

 almost exactly at the same rate (though somewhat less rapidly) 

 as the corresponding valerates. The rate of expansion also 

 diminishes from chlorides to bromides, and thence to iodides, 

 and therefore as the boiling-point increases ; this also holds 

 good, as far as is known, for the halogen compounds of the 

 elements. 



As regards gases, Mendeljeff and Kajander (Deut. chem. 

 Ges. Ber. ix. p. 1311) have recently shown that gases having 

 the same molecular weight have the same coefficient of expan- 

 sion, but that this coefficient increases with the molecular 



