190 
(h) Copper in the green deposit : — 
In order to determine the amount of copper in the com- 
pound, it was dissolved in a very small quantity of dilute 
nitric acid, and the solution thus obtained diluted with 
water to 4,000 measures. 100 measures of this solution 
were then taken and diluted to 1,000 measures, to which 
ammonium sulphide was added, and the tint compared with 
that produced similarly in a standard copper solution, — the 
results thus obtained being multiplied by 40 furnish the 
quantity of copper in the whole of the deposit as follows: — 
Days Exposed. Copper. 
4 0*200 of a grain. 
7 0-320 
14 0-360 
32 0-370 
Adding the quantities of copper found in solution in the 
water to those found in the deposit, we obtain the following 
numbers : — 
Days Exposed. Copper. 
4 0-20675 of a grain. 
7 0-32350 
14 0-36300 
32 0-37000 
As to the green deposit, I found it to consist chiefly of a 
chloride of copper, but I am at present unable to say what 
particular chloride, and as to its formation, I may add that 
by keeping copper-foil immersed in a solution of sodium 
chloride containing 53 grains in 2,000 of water (about the 
quantity present in sea- water), no such deposit is formed 
neither is it formed when copper-foil is kept immersed for 
some time in a solution of magnesium chloride. 
Having made calculations from results given above, I 
append tables showing the action of one gallon (70,000 
grains) of sea- water upon 280 square inches of each metal. 
The quantities are expressed in grains. 
