390 



CEMENTS, LIMES, AND PLASTERS. 



TABLE 169. 

 ANALYSES OF RAW MATERIALS CONTAINING PHOSPHORIC ACID. 



* Including about 1 per cent PzOs- 



TABLE 170. 

 TESTS OF CEMENTS CONTAINING PHOSPHORIC ACID. 



t Including about 2 per cent PgOs. 



Influence of intentionally added fluxes. At a number of plants 

 working on materials or mixtures which are naturally difficult to fuse, 

 experiments have been made on the reduction of the clinkering tem- 

 perature by the addition of fluxing materials. Experiments of this 

 kind are usually taken up in the early stages of the manufacturer's experi- 

 ence. They rarely outlast the first year of actual practice, because 

 he then begins to realize that it is difficult enough to secure a homo- 

 geneous and uniform mixture of two ingredients without going to the 

 extra trouble of adding a third material. Occasionally, however, the 



