28 
and magDesimn sulpbate^ were dissolved with an amount of 
copper sulphate, containing O'lOl grm. Cu. to 1 litre. Vary- 
ing quantities of this solution were taken, and the copper 
estimated therein with the following results, from which it 
is seen that these salts have no detrim.ental effect. 
Copper found. Copper calculated. 
0*54 mgrrn 0-51 mgrm. 
0-71 „ 0-71 „ 
0-91 „ 0-91 „ 
In the same manner the effect of the presence of colour- 
less non-volatile organic matter was tested hy dissolving up 
18 grins, of sugar with an amount of copper sulphate 
equivalent to 0’0505 grin, copper in 1 litre of water, and the 
copper estimated in two different portions as before, the 
following numbers being obtained : — 
Copper found. Copper calculated. 
O' 52 mgrm 0'51 mgrm. 
0-82 „ 0-81 „ 
In order to see what influence the presence of lead might 
exercise on this method of estimating copper, a quantity of 
the sulphate containing 0'255 grm. Cu. was dissolved in 
water, the copper precipitated by potash, washed, and the 
oxide dissolved in nitric acid and the solution after nearly 
neutralizing with ammonia diluted to 1 litre with the ad- 
dition of 2 grm. of lead nitrate — 1’25 grm. Pb. Vary- 
ing quantities of this solution were taken, and the copper in 
them estimated with the following results : — 
Copper found. Copper calculated. 
0’80 mgrm 0'77 mgrm. 
0-75 „ 0-70 „ 
0-51 „ 0'49 „ 
0-49 „ 0-51 „ 
0-38 „ 0-35 „ 
From which it will be seen that lead when present in not 
too large quantity has little or no effect on the accuracy of 
the method. The precipitate obtained on adding potassium 
