THE VOYAGE OF H.M.S. CHALLENGER. 
• 2 : 3 * 
Analysis. 
Old 
Atomic Weights. 
New 
Atomic Weights. 
I. 
In the crude chloroplatinate, by calculation, . 
47-90 
48-35 
I a. 
By calculation from the metal obtained therefrom, 
47-62 
48-53 
II. 
In the pure chloroplatinate, . 
47-06 
47-50 
no. 
Calculating from the metal obtaiued therefrom, 
46-62 
47-51 
hi* 
In filtrate from the crude chloroplatinate, 
2-64 
2-68 
IV. 
In filtrate from the pure chloroplatinate, 
0-85 
0-87 
Sum of II., III., and IV., 
5055 
51-05 
Excess over synthesis, 
0-45 
0-87 
Sum of Her, III., and IV., 
50-11 
51-06 
Excess over synthesis, 
o-oi 
0-88 
Both trials, as critiques of Fresenius’s method, led to the same result. Supposing 
even we had succeeded in obtaining the potash and soda of a sea-water in the shape of 
pure chlorides and without loss of potash, Fresenius’s method, when applied to such a 
mixture, would lead to a deficit in the potash found. According to the second trial 
(which I consider to be the more exact of the two), this deficit, even if we accept the 
crude chloroplatinate as pure and calculate • 
a, by the old atomic weights, amounts to 2‘20 
mgrms. per 50' 10 of K 2 0 given, or 4*4 
per cent. 
b, by the new atomic weights, amounts to 
T83 mgrms. per 50*18 of K 2 0 given, 
or 37 per cent, of the quantity to be 
determined. 
The error of the Finkener method, in the form in which I used it, as appears from my 
memoir, amounts to only about 1 per cent. Hence I was right in preferring the 
Finkener method ; and if Schmelck’s results come so near to mine, this is owing to an 
accidental combination of errors in the execution of his method. 
* The I*tCl # K 2 obtained by Finkener’ s method gave Pt equal to 2 - 75 mgrms. of K.,0 ; the filtrate by Fresenius’s gave 
I“t< '1,K . • * [ti.il t<> 2 55 mgrms. of K./) ; the Pt from the latter corresponded to 2‘52 mgrms.; mean of 2535 and 2‘75 adopted 
(old atomic w eight*). 
