﻿118 



MEIGS ON THE RELATION OF 



It is well known that the potassa and ammonia salts exhibit very complete iso- 

 morphism. This, indeed, might be inferred from the comparison of the nitrates of 

 these bases, as shown in the table. Hence it is probable that potassium and ammo- 

 nium, as has been suspected, are themselves isomorphous, notwithstanding that one 

 atom of nitrogen and four atoms of hydrogen replace one of potassium in combination. 

 I have not the data to compare them, either by heat or volume. 



Phosphorus, arsenic, antimony and bismuth, constitute a natural group to which 

 nitrogen is thought to belong. For the first three the atomic heat is about the same ; 

 the number for bismuth is about one-half that of the others. The relation between 

 the atomic volumes is not so evident. If we follow the example of many of the 

 European chemists, and halve the atomic weights of phosphorus, arsenic and antimony, 

 a tendency to multiple relations between the atomic volumes will become more 

 evident. This tendency is developed in their isomorphous compounds. 



Compounds. 



Atomie 

 Heat. 



Atomic 

 Volume. 



As 2 3 

 Sb 2 3 

 Bi 2 3 



12.68371 

 13.78377 

 14.30929 



26.810 

 26.984 

 27.976 



xlSrj: IO3 



Sb 2 S 3 

 Bi 2 S 3 



13.94600 

 14.87331 

 15.62921 



35.606 

 37.263 



37.257 



As 2 CI, 

 P 2 C1 6 



31.96886 



28.83052 



95.034 



3PbO, PO s 

 3PbO, As0 6 



32.463 

 32.804 



... 



Iodine and bromine are isomorphous throughout their whole combinations. Chlorine 

 in certain respects is naturally associated with them. Their relation in heat and 

 volume is seen below. 



Compounds. 



Atomic 

 Heat. 



Atomic 

 Volume. 



KBr 



KI 



KCI 



NaBr. 



Nal 



NaCI 



AgBr 



Agl 



AgCL 



PbBr 



Pbl 



PbCI 



13.812 

 13.530 

 12.902 



14.061 

 12.950 

 12.541 



18.782 

 14.420 

 13.073 



9.711 

 9.812 

 9.244 



48.612 

 50.322 

 38.955 



28.199 



29.355 

 41.699 

 26.086 



27.481 

 38.166 

 25.217 



