284 
MR. J. B. H ANN AY ON THE MICRORHEOMETER. 
Acids. 
Time. 
Probable error of mean. 
Difference. 
Nitric acid 
131-4 
o-ll 
+ o-i 
Hydrochloric acid 
136-3 
0-23 
+ 5-0 
Sulphuric acid 
141-8 
0-07 
10-5 
Now leaving out the acids, which have evidently a special action on water (for a 
reason given further on), if we take the difference between the nitrate and chloride 
of any metal we find it has a constant value. The same holds good for the difference 
between chloride and sulphate or between the various salts of any two metals. Thus 
we find a constant value for chlorine and the acid radicles as well as for the individual 
metals, and these values are extremely constant, as will be seen from the subjoined 
table. There are a few cases in which there would appear to be a slight divergence, 
but these are in hydrated salts, and the reason is easily found. The following table 
gives the differences :— 
Difference between 4N 2 0 5 
and Cl in 
Difference between Cl and 
iS0 3 in 
f Metals. 
u 
Potassium 
2-7 
Sodium 
2-6 
Ammonium 
2-6 
j Magnesium 
2-3 
Barium 
2-6 
Strontium 
2-6 
Calcium 
2-6 
p Copper 
2-7 
f Potassium 
14-6 
j Sodium 
14-8 
i Ammonium 
14-4 
Magnesium 
14-6 
Calcium 
14-6 
pCopper 
14-5 
The total difference between the extremes of the three inorganic acids is an average 
of 17-2". 
The difference between chloride ana bromide in the potassium salts is 2'G", and 
between bromide and iodide 2'5": the total difference between the chloride and 
iodide in both potassium and sodium salts being 5T". Two facts are brought out by 
these numbers : first, that the bodies containing the greatest amount of energy offer 
the least resistance in the tube—for instance, nitrates all flow fastest, and sulphates, 
which are fully exhausted compounds, flow slowest; the second fact is that the greater 
the mass the less resistance does it offer. We see this in the cases of the chlorides, 
bromides, and iodides, the last having; the highest combining weight, and hence the 
greatest chemical mass, flow much easier than either of the others. Let us now 
examine the metals. 
