J. H. Talbot—Precipitation of Zinc and Manganese. 245 
tremely difficult to wash. The precipitation is, however, more 
complete than when sodic carbonate is use 
dered very easy and rapid by the following process : The Aes 
tion of zine, if acid, is to be neutralized as nearly as possible 
bye pave or ammonie carbonate. To the boiling solution sodic 
monic sulphid is to be added, a large excess being very 
d The white pr ecipitate, on anes boiling, 
soon becomes granular, and settles rea eer sirtronaney 
a gr. pure 220 ga gave 0 je gr. = 100-00 pr. ct. 
0°3208 gr. 0°3209 or. = 100-03 pr. ct. 
Otigee = 87 ee 2410 gr. = 99°91 pr. ct. 
01785 gr. “§ “ © 01784 gr. = 99°94 pr. ct. 
In zincic sulphate, which had probably lost a little water: 
0°6485 gr. gave 0°1851 gr. ant) = a ‘54 pr. ct. 
06510 gr. “ O1858 gr “ ‘54 pr. ct. 
OC198 gr. * Oe8 oe au 52 pr. ct. 
The formula requires 28°29 pr. ct. ZnO. The advantages of 
this process over the older methods of precipitating in the cold 
are, I think, ve aren even if only the saving of time be 
taken into considera 
Manganese may i ‘pedguans completely from its boilin 
solutions by precisely the same process. e flesh-colore 
sulphid is granu oa an . re even sandy, though not 
distinctly crys may be washed with the utmost 
snrone pha in the manner y Prof. Gibbs. 
To test the method with a perfectly de * yore 
manganous pyrophosphate was selec rat dissolved in dilute 
chlorhydrie acid, and the solution age neutralized by sodic 
