W. Gibbs—Contributions to Chemistry. 211 
tain the precipitate in a spongy coherent form, it is best not to 
allow the liquid to boil. The solution of hypophosphite having 
been added in the cold and in excess, the temperature is to be 
gradually raised until, after standing for some minutes between 
80° ©. and 90° C., the hydruret of copper has entirely separated 
in coherent masses. It is easy to determine when the ipi 
tion is complete by taking out a drop of the clear liquid with 
arod and testing upon a porcelain plate with a drop of sulphy- 
dric acid solution. No filter need be used if the precipitation 
be effected in an assay flask; the ~~ is easily wash 
cantation, and may then be transferr 
1650 gr. pure sulp pper gave 0-2966 gr. copper==25°45 p. c, (Chauvenet.) 
2. 1.5590 gr. s“ “ “ 0°3970 gr. “« =—9545 “ “ 
8, 14955 gr. “« & “ 08625 gr “ —=95'43 « 
4.18050 gr.“ « «4 Qggo7gr. “ =2642 “(R.B.Carman) 
5. 08208 gr.“ x « Q-2087gr. “ =2542 “ (E. F. Gale.) 
Tn (4) and (5) a large excess of sulphate of nickel was present. 
The formula €uS@, +5aq gives 25°42 per cent of copper. In 
the third analysis sulphates of iron, manganese, nickel and zine 
In very large excess were added to the cag of ORDO 
n a very pure subsulphid of copper irom Arizona, ST. 
Chauvenet eile four analyses 74°24, 74°37, 74°36 and 74:41 
per cent copper. . 
II. In an alloy of copper and nickel 
6. 04245 or. gave 0:3605 er. of copper 8492 per cent. (Chauvenet.) 
7. 0°3615 oe Bu 0-070 oe amen yery males - 
8.01380 gr. “ O1170gr. = =8485 M . 
9.01980 or, “ 0°1680 gr. “ =8484 “ :, 
III. In brass wire 
10. 1:6300 or. gave 1.0705 gr. of copper 65°67 per cent, (Chauvenet. 
11. 1.8655 a or 1:2240 er % 65°61: -% ¥ 
12.16770 gr. “ 1:1010gr. “ =6565 
In the last seven analyses the alloy was dissolved in sulphutie 
“ sc 
Tet. A solution of ; h osphite reduces sesquichlorid 0 iron 
‘0 protochlorid : elie! peciatoes js particularly rapid and com- 
