i0me ^attB an %mxmi P^ortars. 



By ALFRED C. FRYER, Ph.D., M.A. 



MORTAR has been defined as a mixture of slaked lime 

 and sand in proper proportions, and when this mixture 

 is spread in thin layers between stones or bricks it gradu- 

 ally hardens and acquires a considerable degree of tenacity, 

 in a gTcat measure from its gradual conversion into car- 

 bonate of lime, combining at the same time with the sub- 

 stance of the brick or stone. Although the mortar becomes 

 sufficiently hard in a few days to bear considerable pressure, 

 yet its maximum degree of hardness is not reached until 

 the lapse of many years, and even centuries. Pliny tells us 

 that the Romans prepared their mortars some time before 

 they were used, and he further points out that the lime was 

 slaked in pits and allowed to remain there for two or three 

 years before it was actually required. 



It was early discovered that lime reacts on certain bodies 

 different from it in composition, especially when they were 

 of a silicious nature. The ancients took advantage of this 

 fact, and at an early period sand was employed to multiply 

 the surface of contact, bring the whole of the hydrate of 

 lime into active combination, as well with this as with the 



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