Intelligence and Miscellaneous Articles. 



399 



and, later, that the haloid salts of some of these metals had mole- 

 cular volumes multiples of that of hydrogen. For this latter relation, 

 however, my materials were meagre. I had then the specific-gra- 

 vity determinations for LiCl, NaCl, KC1, NaBr, KBr, Nal, and K.I, 

 or seven compounds in all. To these I added, though unsatisfac- 

 torily, the corresponding salts of silver, making a list of ten bodies 

 closely related, and giviug volumes multiples of 5- 5, the value as- 

 signed by Kopp to hydrogen in its liquid compounds at their 

 boiling-points. This relation I am now able to extend, partly by 

 new density-observations of my own, to include at least twelve 

 compounds not in my earlier list. 



My own determinations, in addition to those I have already given 

 for the alkaline fluorides, are as follows : — Eubidium chloride, 2-209, 

 19°; rubidium bromide, 2-780, 17°'5; rubidium iodide, 3-023, 22°; 

 lithium bromide, 3-102, 17°; lithium iodide, 3-485, 23°. 



Now let us tabulate the material. The first column contains the 

 symbol of the substance, the second its density with authority 

 given, the third its molecular volume as found, the fourth its volume 

 calculated, the fifth a theoretical density deduced from this volume. 

 The calculated volumes are of course the exact multiples of Kopp's 

 hydrogen value, and will be seen at once to agree closely with the 

 results of experiment. The real variation between fact and theory, 

 however, will be best seen upon comparing the two columns of 

 densities. The differences here are always less than 0*1. 



I. 



II. 



III. 



IV. 



y. 



LiF 



2-295, Clarke. 



11-33 



11-00 



2-363 



LiCl 



1-998, Kremers. 



21-27 



22-00 



1-932 



LiBr 



3-102, Clarke. 



28-05 



27-50 



3-164 



Lil 



3-485, „ 



38-45 



38-50 



3-481 



NaF 



2-558, „ 



16-41 



16-50 



2545 



NaCl 



2" 145, Bruignet. 



27-27 



27-50 



2-127 



NaBr 



3079, Kremers. 



33-45 



33-00 



3421 



Nal 



3-450, Filhol. 



43-48 



44-00 



3-409 



KF 



2-096, Clarke. 



28-20 



27-50 



2-113 



KC1 



1-945, Kopp. 



38-35 



38-50 



1-937 



KBr 



2-672, Playfair, Joule. 



44-57 



44-00 



2-707 



KI 



3-056, Filhol. 



54-35 



55-00 



3-020 



RbF 



3-202, Clarke. 



32-64 



33-00 



3-167 



E.bCl 



2-209, „ 



54-78 



55-00 



2-200 



KbBr 



2-780, „ 



59-53 



60-50 



2-735 



Rbl 



3-023, „ 



70-29 



71-50 



2-972 



Here, now, we have sixteen compounds of a single type, every one 

 of which agrees with the rule. In each case the molecular volume 

 comes out a multiple of 5-5, or very nearly. Only one substance in 

 the list seems to be in any way abnornal, namely, rubidium fluoride, 

 with its volume of 33. The other fluorides in this group have volumes 

 less by 11 than those of the corresponding chlorides ; but in this 

 case the difference is 22. A curious progressive relation is also 

 worth noting. If we compare the five chlorides given in the Table 

 we shall see that, upon arranging them in the order of their mole- 

 cular weights, the differences between successive members of the 

 series increase as we ascend. Thus LiCl and NaCl differ by 5'5. 



