31 
Ordinary Meeting, November 80tb, 1875. 
Edwabd Schunck, Pli.D., F.RS., &c., President, in the 
Chair, 
On the Estimation of very small quantities of Lead and 
Copper,” by M. M. Pattison Muib, F.RS.E., ilssistant 
Lecturer on Chemistry, Owens College. 
As I have lately been occupied with experiments upon 
the action of saline solutions upon lead and copper, which 
involved the measurement of very small quantities of these 
metals I thought it might be well to test the accuracy and 
delicacy of the method employed. 
The method itself is in no way iiev/, being that described 
by Wanklyn in his Book on Water Analysis.” The depth of 
colour produced by the addition of sulphuretted hydrogen 
water to a known volume of the liquid under examination 
is compared with the colour produced, by the same means, 
in an equal volume of water to which a known amount of 
lead or copper, in solution, has been added. In comparing 
the colour of the liquid under examination with the 
standard liquid I find it preferable to employ stout glass 
tubes, holding about 100 cc. and having a diameter of about 
1-5 cm., rather than white porcelain dishes a.s recommended 
by Wanklyn. The contents of the tubes are thoroughly 
mixed by means of glass tubes on the ends of which bulbs 
have been blown. (See Thorpe on a method of estimating 
nitric acid, &c. Chem. Soc. J. [2] XI. 547.) 
Wanklyn recommends the use of standard solutions, 1 cc. 
of which is equal to 1 mgm. of copper or of lead : he em- 
ploys 70 cc. of the water to be tested. If, therefore, the 
colour produced on adding sulphuretted hydrogen Avater to 
70 cc. of the liquid under examination is found to be equal 
Proceedings — Lit, & Phil. Soc. — Vol. XY. — No, S.—Session 1875-6. 
