Here reported test on the germs of crystallization prepared by pulverizing hydrated cement for accelerating hardening of cement, originated with Messrs. Duriez and Lezy.

Strength tests on mortars with or without germ were made and the test results showed that portland cement germs are considerably effective when added some chemi cals or mixed into portland blast furnace slag cement mixture.

*Manuscript received on September 29, 1961