]82 <>W MORTAR. 



It is of the greatest importance to determine with preci- 

 tion the quantity of lime employed to obtain the most solid 

 ptiortarti or cements; and in general to use no lime but what 

 has been made from pure limestone, and which has been 

 kept well secured from the air after it is slacked. 

 Two parts of In the experiments of Mr. Sage he always employed two 



of"o*rhc/maf- ^^^^^9^ l''"5*^ ^^'■*^« 9^' pnzzolana, of sand, &c., which af- 

 ter, forded him very hard and impermeable mortar : and he thinks 

 this proportion of lime may even be lessened, when the 

 architect is fully convinced of the impropriety of leaving 

 the preparation of mortar to bricklayer's labourers, since the 

 strength and solidity of hydraulic structures depends so 

 much on it. 

 Mortar> of The author has divided his experiments into five classes, 

 hmt and ashes, j. Mortars or cements made with substances, that have un- 

 dergone the action of fire. The ashes of vegetables, whe- 

 ther lixiviated or not, being mixed with two thirds of lime 

 slacked by immersion, forms one of the most solid and im- 

 permeable cements: a property which they appear to derive 

 from the minutely divided quarts;, which these ashes contain 

 in the proportion of one fourth. 

 Lime andiron 2. Mortars or cements made with metallic substances. 

 oxide. Iron adds to the hardness of all mortars; and of itself, in 

 l"usting, copcups in the agglutination of gravel and pebbles. 

 Iron alone a as we see on the seashore. According to the state in which 

 cement. ^^^ -^.^^ j^^ ^j^^^, j^ combined with two parts of slacked lime, 



its force of cohesjon is more or less considerable. 

 Lime anddif- 3* Mortars or cements made with jtones of different na- 

 ftsrent itones. tures, Gaestein, chalcedony, sandstone, and gravel, form 

 very hard and impermeable mortar with lime. Feldspar, bet- 

 ter known by the name of petuntse, being mixed with two 

 thirds of slacked lirue, produces an impermeable and solid. 

 N mortar^ 



4. Mortars or cements that ^Iter in water. Vesjetable 

 l.irne and . , , • • n i .- • i ,. 



jnould. earth, or mould, is essentially composed of minutely di- 



vided quartz, clay, and iron. Mixed with two parts of 

 slacked lime, and water enough to form a soft paste, the 

 brick produced from it, when dried, has some solidity, 

 ifbieh it loses under water, where it cracks. 

 X-ime an4 6» Mprtars or cpment^ oaadje with copnbustible substances. 



Mortar> 



