MR. J. 13. HARRAY ON THE MICRORHEOMETER, 
285 
Potassium offers the least resistance of the metals (we will not consider ammonium 
a metal just now), and we will call it zero. Taking all the salts into consideration, we 
have the following differences :— 
Metals. 
Differences. 
Potassium 
// 
0 
Sodium 
+ 11-6 
Barium 
+ 15-0 
Strontium 
+ 16-8 
Calcium 
+ 18-6 
Copper 
+ 23-8 
Magnesium 
+ 28-6 
Here the second of the above laws comes out very clearly: the greater the chemical 
mass the less the retardation. In the series of barium, strontium, and calcium, which 
are analogous metals, this comes out with numerical exactness. 
The difference between the metalloids in combination also illustrates these laws. 
The following table will exhibit this : — 
Difference between Cl and Br in K salts 2 - 6 
,, ,, Br and I in „ 2‘5 
5-1 
Difference between Cl and I in Na salt 5T 
Here the greater mass of iodine causes the salt to pass much more easily through 
the microrheometer. We must not forget, however, that the heat of formation of those 
salts varies very much, and not only has the chloride the lowest mass but it has evolved 
most energy in its formation. In considering the relation between mass and energy, 
we had perhaps better look at two series, such as the following :— 
Elements. 
Equivalents. 
Differences. 
Rates. 
Differences. 
Iodine 
127 
0 
-7-4 
0 
Bromine 
80 
47 
-4-9 
2-5 
Chlorine 
35-5 
44-5 
-2-3 
2-6 
Barium 
137 
0 
10-1 
0 
Strontium 
87-6 
49-4 
11-9 
1-8 
Calcium 
40 
47-6 
137 
P8 
Now it will be seen that although the masses of the metallic bodies are considerably 
greater than those of the metalloids, and their differences are greater, yet the effect in 
the microrheometer is much less. 
Again, looking at the rates of the three inorganic acids, it seems clear that water 
has a special reaction for each acid, as the rates are not removed from each other by the 
same differences as when metallic solutions are employed, thus— 
