METHODS OF SAMPLING AND TESTING HIGHWAY MATERIALS 101 
By multiplying by 2. the figures for coating in ounces per square foot of 
actual surface may be compared with the figures for coating in ounces per 
square foot on zinc-coated sheets. 
HYDROCHLORIC ACID-ANTIMONY CHLORIDE METHOD (STANDARD 
METHOD) 
SOLUTIONS REQUIRED 
Antimony chloride solution. — Dissolve 20 grams of antimony trioxide or 32 
grams of SbCla in 1,000 cubic centimeters of HC1 (specific gravity approxi- 
mately 1.19). 
Hydrochloric acid.— Concentrated HG1 (specific gravity approximately 1.19). 
mutely 1.19). 
METHOD 
(a) Sheets. — Cut three 2 1 / i by 2 1 / i inches (or equivalent area), laboratory sam- 
ples, as described under ••Sampling," and weigh together 45 after cleaning and 
drying. They should be immersed singly in 100 cubic centimeters of hydro- 
chloric acid (specific gravity approximately 1.19). to which has been added 5 
cubic centimeters of antimony chloride solution, and allowed to remain therein 
until the evolution of hydrogen has ceased or until only a few bubbles are 
being evolved. This requires only about 15 to 30 seconds, except in the case of 
sherardized coatings, which require a somewhat longer time. The same 100 
cubic centimeters of hydrochloric acid can be used for at least five samples, 
but 5 cubic centimeters of the antimony chloride solution should be added before 
the immersion of each sample. After stripping the samples should be washed 
and scrubbed under running water, dried with a towel, and laid in a warm 
place for a short time. The samples should again be weighed together 45 and 
the number of grams lost divided by the number of samples taken. Each gram 
then corresponds numerically to 1 ounce of coating per square foot. 
(&) Wire. — A ^rnall section of the zinc-coated wire should be stripped in 
hydrochloric acid containing antimony chloride and the diameter of the stripped 
wire determined. 
To determine the weight of coating the sample is carefully weighed to 0.01 
gram. The wire is then placed in a tall cylinder containing hydrochloric acid 
(specific gravity approximately 1.19) to which has been added 2 to 3 cubic 
centimeters of antimony chloride solution of the same strength as is used in the 
testing of sheets. After stripping the wire is washed under running water, 
dried, and laid in a warm place for a short time. The loss in weight repre- 
sents the zinc coating, and if the length of wire designated in Table 8 is used 
the coating in grams will be numerically, equal to the coating in ounces per 
square foot of actual surface. In order to compare this figure with that given 
for sheets it must be multiplied by 2. 
BASIC LEAD ACETATE METHOD (ALTERNATE METHOD) 
SOLUTIONS REQUIRED 
Lead acetate solution. — Dissolve 400 grams of crystallized lead acetate in 1 
liter of water. When dissolved add 4 grams of finely powdered litharge, and 
after thorough agitation allow the solution to settle and decant the clear 
portion for use. 
METHOD 
Cut three 2% by 2*4 inch (or of equivalent area) laboratory samples, clean 
and weigh as described in the hydrochloric acid-antimony chloride method. 4 " 
The samples should then be submerged separately in a tumbler containing 
sufficient lead acetate solution to cover the samples. The samples should be 
45 If it is of interest to know the individual weight of coating on each piece, each must 
be analyzed individually instead of collectively, as described. 
46 See footnote 45. 
