178 Miscellanies. 



3. On the Isomeric bodies of J. J. Berzelius. — The number of 

 known bodies, which show different properties, notwithstanding their 

 equal qualitative and quantitative composition, has increased of late 

 very considerably. By the name of isomeric bodies, we signify such 

 substances as possess by equal quantitative (per cent.) composition, 

 also equal atomical weight ; but Berzelius has, quite recently made 

 more distinctions on the same, and defines them by the name of 

 isomeric, metameric and polymeric bodies : 



1. Isomerism ; bodies possessing equal procentic (quantitative) 

 composition, and equal atomical weighi, or bodies composed of equal 

 absolute and relative number of atoms, as for instance the two oxides 

 of tin, both the phosphoric acids, he. 



2. Metamerism, (properly a modified isomerism,) where the same 

 number of equal simple atoms are unequally distributed among com- 



• •• 



pound atoms of the first order ; for instance, sulphate of tin (Sn S) 



and di-sulphate of tin (Sn S) possess an equal, absolute and relative 

 number of the same elements, they are however to be considered 

 (should the latter salt be really in existence, which is not hitherto 

 known,) as different bodies, which may however unite by transposing 

 their constituents. The cyanuric and hydrocyanic acids exhibit 

 another instance of metamerism. 



3. Polymerism ; bodies having equal quantitative composition, bat 

 unequal atomical weight, or where bodies have an equal relative but 

 unequal absolute number of atoms ; for instance, the relative atomi- 

 cal number of carbon and hydrogen in the defiant gas and ethereal 

 oil is quite alike, for the number of atoms of hydrogen is in both 

 twice as much as that of the atoms of carbon ; but one atom of the 

 gas contains but one atom of carbon and two atoms of hydrogen, 

 (CH 2 ) whereas one atom of the oil contains four atoms carbon and 

 eight atoms hydrogen (OH 8 ). Itjs very desirable that a general 

 term should be given for designating these three classes, and it is the 

 more necessary on account of many substances not yet having a de- 

 termined atomical weight, and we should be at a loss to classify many 

 bodies, which show equal properties and equal composition. — Trans- 

 lated by Dr. Lewis Feuchtwanger. 



* 



4. Sparks in the freezing of water by ether. — Pontus, professor of 

 chemistry at Cahors, has observed, that if the freezing of water is 

 performed in a small glass bottle, terminating in a thin neck of 1—2 



cent, length, around which some cotton, moistened with ether rs wrap- 



