SAMPLING AXD TESTING HIGHWAY MATERIALS. 93 
specific gravity of 1.186 at 65° F. (reading the scale at the 
level of the solution) at the beginning of each test. In 
the filtered solution is high in specific gravity, clean water shall 
be added to reduce the specific gravity to 1.156 at 65° V. In 
case the filtered solution is Low in specific gravity, filtered solu- 
tion of a higher specific gravity shall be added to make the 
specific gravity 1.1S8 at 6"» 3 F. 
7. As soon as the stronger solution is taken from the vessel 
containing the unfiltered neutralized stock solution, additional 
crystals and water must be added r<> the stock solution. An 
excess of copric oxide shall always be kept in the unfilled 
stock solution. 
8. (d) Quantity of solution. — Wire samples shall be tested 
in a glass jar of at least 2 inches inside diameter. The jar 
without the wire samples shall be filled with standard solution 
to a depth of at least 4 inches. 
9. Solution shall not be used for more than one series of four 
immersions. 
10. (e) Samples. — Not more than seven wires shall be simul- Samples. 
taneously immersed in the specified quantity of solution 
11. The samples shall not be grouped "r twisted together, bur 
shall be well separated so as to permit the action of rite - 
tion to be uniform upon all immersed portions of the samples. 
12. (f) Test. — Clean and dry samples shall be immersed in Metkod of test. 
the required quantity of standard solution in accordance with 
the cycle of immersions called for in the specificati 
13. The temperature of the solution shall be maintained be- 
tween 62° and 68° F. at all times during the te<r. 
14. After each immersion the samples shall be immediately 
washed in clean water having a temperature between 62° and 
68° F. and wiped dry with cotton wa-te. 
15. (g) Rejection. — If after the test described in sootion (f) 
there should be a bright metallic copper deposit upon the sam- 
ples, the lot represented by the samples shall be rejected. 
16. Copper deposits on zinc or within 1 incb of the out end 
shall not be considered causes for rejection. 
17. In case of a failure of only one wire in a group of seven 
wires immersed together, or if there is i\ reasonable doubt as 
to the copper deposit, two cheek tosts shall be made on these 
seven wires and the lot reported in accordance with the majority 
of the sets of tests 
Note. — The equipment necessary for the fe<t herein outlim 
as follow- : 
Commercial copper sulphate Tray for holding jars of - 
crystals. solution. 
Chemically pure cupric oxide Jars, bottles, and porcelain 
<CuO). . -i for stock solution. 
Running water. Cotton v. 
Warm water or ice as per Hydrometer cylinder 3 in< hes 
needs. in diameter by 15 inches 
Carbona. benzine, or tnrpen- high. 
tine. 
Glass jars at least 2 inches 
Inside diameter by at least 
41 inches high. 
Glass or earthenware jars for I .5 F 
hardware samples. Filter paper. 
Vessel for washing sampler 
Thermometer with large Fah- 
renheit scale correct at 62° 
aid I 8 
Ilydromernr correct at 1.186 
