314 ANNUAL REPORT 
41. ‘The setting is said to have commenced when the needle ceases 
to pass a point 5 mm. (0.20 in.) above the upper surface of the glass 
plate, and is said to have terminated the moment the needle does not 
sink visibly into the mass. 
42. ‘The test pieces should be stored in moist air during tke test; 
this is accomplished by placing them on a rack over water contained in 
a pan and covered with a damp cloth, the cloth to be kept away from 
them by means of a wire screen; or they may be stored in a moist box 
or closet. 
43. Care should be taken to keep the needle clean, as the collection 
of cement on the sides of the needle retards the penetration, while cement 
on the point reduces the area and tends to increase the penetration. 
44. ‘The determination of the time of setting is only approximate, 
being materially affected by the temperature of the mixing water, the 
temperature and humidity of the air during the test, the percentage of 
water used, and the amount of molding the paste receives. 
STANDARD SAND. 
45. [he committee recognizes the grave objections to the standard 
quartz now generally used, especially on account of its high, percentage 
of voids, the difficulty of compacting in the molds, and its lack of uni- 
formity ; it has spent much time in investigating the various natural sands 
which appeared to be available and suitable for use. 
46. For the present the committee recommends the natural sand 
from Ottawa, Ill., screened to pass a sieve having 20 meshes per linear 
inch and retained on a sieve having 30 meshes per linear inch; the wires to 
have diameters of 0.0165 and 0.0112 inch, respectively, i. e., half the width 
of the opening in each case. 
47. The Sandusky Portland Cement Company, of Sandusky, Ohio, 
has agreed to undertake the preparation of this sand, and to furnish it at 
a price only sufficient to cover the actual cost of preparation. 
FORM OF BRIQUETTE. 
A8. While the form of a briquette recommended by a former com- 
mittee of the society is not wholly satisfactory, this committee is not pre- 
pared to suggest any change, other than rounding off the corners by 
curves of % inch radius (figure 80). 
MOLDS. 
49. The molds should be made of brass, bronze or some equally 
non-corrodible material, having sufficient metal in the sides to prevent 
spreading during molding. 
50. Gang molds, which permit molding a number of briquettes at 
one time, are preferred by many to single molds, since the greater quantity 
