16 BULLETIN 949. U. S. DEPARTMENT OE AGRICULTURE. 
Mix 50 grams of the material parsing the 10-inesh sieve with — 3 grams of water 
and knead with the hands into a spherical ball. Measure the diameter. Let this 
ball drop from a height of — 3 cm. on a flat slab. Measure and record the reduction 
in diameter and examine the surface for cracks. 
Usually the plastic character arid adhesiveness of a good road soil can be judged by 
the feeling of the mud made from the material, its adherence to the hands and its 
stretch under light pulling. 
14. TESTS FOR QUALITY OF WATER TO BE USED IN CONCRETE. 
(U Acidity andaV:alin ity. — The acidity and alkalinity test shall be made by immers- 
ing strips of blue and red litmus paper in a vessel of the water for a period of five 
minutes and noting color. A marked reversal in color indicates excessive acidity or 
alkalinity and the necessity for further tests. 
(2) Total solids and inorganic matter. — Five hundred '500 | cubic centimeters of the 
water shall be evaporated to dryness in a weighed dish. For this purpose a platinum 
dish of 100 to 200 c. c. capacity is found most convenient. The dish shall be nearly 
filled with the water and placed on a water bath, additional portions of the sample of 
water being added from time to time until 500 c. c. have been used. The contents of 
the dish shall be evaporated to dryness and the dish and contents cooled in a dessicator 
and weighed. The weight of the residue in grams divided by 5 is the per cent of total 
solids in the water. 
(3) The total solids obtained as described, may consist of organic matter, of inor- 
ganic matter, or of combinations of organic and inorganic matter. The platinum dish 
shall be ignited at low red heat, and the darkening of the residue during the early 
stage of the ignition usually indicates the presence of organic matter. The per cent 
loss on ignition at low red heat will usually be an indication of the amount of organic 
matter, but it should be noted that some mineral salts tend to volatilize or partly 
decompose on heating. 
(4) The determination of the decomposition of the mineral matter in the water 
usually requires a complete chemical analysis of the total solids obtained by the 
evaporation of 500 c. c... or more, of the water, and is not generally undertaken except 
when the percentage of total solids is large, or the water appears to give abnormal tests 
in other respects. 
(5) A comparison of the given water with a water of known satisfactory quality can 
be obtained by making standard soundness, time ?i setting, and 1 : 3 mortar strength 
tests with standard sand, using the same cement c standard quality with each water. 
(Suggested limits for the last-named test are as folic s : Any indication of unsoundness, 
marked change in time of setting, or a variation . . more than 10 per cent in strength 
from results obtained with mixtures containing the water of satisfactory quality, shall 
be sufficient cause for rejection of the water under test. 
15. TEST FOR ORGANIC IMPURITIES IN CONCRETE AGGREGATES. 
The test recommended is described in the "Proceedings of the American Society 
for Testing Materials. Philadelphia. Pa.. Volume XIX. part 1. 1919, Appendix to 
Report of Committee C-9 on Concrete and Concrete Aggregates.'" 
(1) The test as usually made consists of shaking the sand thoroughly in a dilute 
solution of sodium hydroxide (XaOH) and observing the resultant color after the 
mixture has been allowed to stand for a few hours. Fill a 12-oz. graduated prescrip- 
tion bottle to the -H-oz. mark with the sand to be tested. Add a 3 per cent solution of 
sodium hydroxide until the volume of the sand and solution, after shaking, amounts to 
7 ounces. Shake thoroughly and let stand for 24 hours. Observe the color of the clear 
3 No definite weight of water or height of fall recommended. 
