5 BULLETIN 572, U. S. DEPARTMENT OF AGRICULTURE. 
In a communication received from the manager of one of the large 
cement plants in the Lehigh Valley district the statement was 
made that the raw cement material used in this district contains less 
than 0.3 per cent. The samples analyzed in these experiments, 
however, indicate that in no case does the raw mix used in the plants 
of this district run as low as 0.3 per cent, but that some of these 
plants make use of cement material almost as rich in potash as may 
be found in any cement plant in the country. In general it may be 
stated, however, that high potash-bearing raw material is not char- 
acteristic of any particular part of the country. 
The values given in Table I for the potash contained in the daily 
production of cement were obtained by multiplying the output in 
barrels by the weight of one barrel (380 pounds) and by the per- 
centage of potash in the cement as found by analysis. To obtain 
the corresponding values for the potash 1 in the daily run of raw mix, 
the output of cement expressed in barrels was multiplied by the 
weight of raw mix required per barrel of cement and then by the 
percentage of potash in the raw mix. The difference between the 
two values as thus determined represents the potash that escapes 
daily from the kilns. As shown in the table, this varies in different 
plants from 0.35 to 5.14 pounds of K,O per barrel of cement pro- 
duced. The average for all the plants listed in the table when 
consideration is taken of the variation in output of cement of the 
different plants amounts to 1.93 pounds?! per barrel of cement. 
Omitting the plants of the Universal Portland Cement Co., the 
corresponding average for the remainder of the 99 plants of this 
country from which samples were received amounts to 2.09 pounds. 
The average for the nine Canadian plants is 1.95 pounds. The 
total number of plants in this country from which samples were 
received is only four less than the total number which operated in 
1915” and nine less than the total number said to be in operation 
in 1916. 
The average daily output of cement from the individual plants in 
many cases is considered confidential information. In Table I, 
therefore, it was necessary to give values for the output of the indi- 
vidual plants which represent capacities rather than actual produc- 
tion. The total annual production as obtained from these values 
is consequently much in excess of that which is known to have been 
produced in any one year. The values given for the potash lost 
per barrel of cement are, however, independent of the output. If, 
therefore, the average annual production of Portland cement in 
amount to more than a few tenths of a pound per barrel of cement. Any potash present, however, would 
tend to increase the value given for the amount of potash volatilized. Cf. R. K. Meade, Portland Cement, 
2d ed., p. 179. 
2 Burchard, E. F., Cement in 1915. Mineral resources of the U. S., 1915, Part II, p. 195. 
