244 oJ. H. Talbot—Precipitation of Zine and Manganese. 
Tron.—Good results could not be obtained by the en 
of this method to the determination of iron, but I am a 
present able to assign the reason of the failure in this in 
To complete my work it remains for me to point out the 
appncibilie of the process to the determination of the whole 
quantity o of oxygen contained in a number of bases present 
together in solution—a problem which is sometimes of interest. 
Sulphates of Manganese, Magnesium, Nickel, Cobalt, Cad- 
mium and Zine in undetermined quantities were dissolved to- 
gether in water, and the solution well shaken. Four portions, 
gen in the acid was then calculated from the amonnt of baric 
sulphate this manner it was found that the oxygen in the 
acid was to that in the mixed bases as 3 to 1 a nearly, the 
precise ratio being in the one case as 0-054 is to ae and in 
the other as 0°055 is to 0018. Another experiment w ae 
with a crystallized dolomite containing 0°45 pr. ct. of canta 
residue. The lime, magnesia and iron were precipitated to- 
gether, and titrated as oxalates; the carbonic acid was deter- 
mined by ignition. In this manner the oxygen of the acid 
was found to be to the oxygen in the bases as bes ‘48 is to 17-28. 
The bases after ignition amounted to 52°41 
In another experiment with a dolomite oie a "different local- 
ity containing 0-13 pr. ct. of insoluble residue, the oxygen ratio 
was found to be as 84°56 is to 17-28, the bases amounting to 52°33 
pr. ct. Roth we calculate the relative quantities of calcic and 
magnes nat m the sum of the two oxyds in the last 
sian a the oxygen oad by titrating the oxalate, we find: 
MgCo, 1 - = “3 42°77 
CaCO, - - - a - 57-07 
Insol. residue a = : 0713 
9g 97 
eration of the use of potassic Eypennatgenat, w which will 
who employ this reagent fre- 
cgaeertty in f yaltanege analyses. 
§ 2. 
On new analytical processes ; by J. H. TALBOTT. 
On the precipitation of zine and manganese as sulphids.— 
Zine is thrown down from cold solution by an alkaline ysulphid 
in the form of a slimy mass which settles slowly and is ex- 
Sa ee a ye 
