266 ' EARTHS. 



Manganesian and ferruginous limestones are valuable in this respect, 

 and a portion of silica and alumine in the composition of the lime- 

 stone improves it for these purposes.* 



Recipe for water mortar. f Blue, clay, 4 parts, manganese, 6, 

 limestone 90, and all in powder ; calcine, mix with sand 60 parts, and 

 form it into a mortar, with water. The tarras,J used for the con- 

 struction of dykes in Holland, is merely an ancient decomposed lava 

 from the extinct volcanos on the Rhine ; some call it a decomposed 

 basalt, and it is certain that the rocks of this family, are effectual in 

 this way, if previously decomposed, or calcined, so that they can be 

 broken down and intimately mixed with the lime. Parker's ce- 

 ment is composed of silica, 22, alumine, 9, oxide of iron and manga- 

 nese, 13, carbonate of lime, 55 = 99, and there was in the analysis a 

 loss of 3.25. The white cement used in New Haven to cover stone 

 houses, is composed of the best slacked lime, 1 part, by measure, 

 and from 3 to 5 measures of coarse siliceous sand and some hair, 

 well beaten together, and laid on with a trowel ; the workmen pre- 

 tend to add sugar, and various salts, particularly the sulphate of pot- 

 ash ; but having tried the mortar, both with and without these addi- 

 tions, I am persuaded that they are of no importance, and that the 

 cement of coarse sand, hair and lime, alone, will stand any length of 

 time, provided water does not get beneath ; if it does, the first freez- 

 ing will crack the mortar, and throw it off. 



Lime is of great use in Agriculture. In the form of carbonate of 

 lime, it is often mixed with soils, and will be mentioned again. In 

 the state of quick lime it is largely used in England, where it is com- 

 mon to see extensive tracts covered with heaps of it. || It appears 

 to be a part of the food of plants, as it is found in the ashes of most of 

 them, and it may be also a stimulus to vegetable life. Its immedi- 

 ate action, when caustic, is to destroy vegetable organization, and it 

 appears to act as a manure, principally by decomposing hard dry 



* Hydraulic lime of the state of New York, contains according to Dr. Hadley's 

 analysis, carbonic acid 35.05, lime 25, silex 15.05, alumine 16.05, water 5.03, oxide 

 of iron 2.02. Am. Jour. Vol. Ill, p. 231. 



t Hydraulic lime is found at Southington, Connecticut, near the canal, and in 

 many places on the Erie Canal. See Am. Jour. Vol Xlll, p. 382. 



i The proportions said to be used in Holland, are tarras 1 part, and slacked lime 2 

 parts. 



I saw them preparing the trap rocks in this manner, at Greenock, where (1806,) 

 they were making hydraulic mortar for a dock. The porous and vesicular trap 

 which they used was from the neighboring isle of Arran. That in East Haven, 

 which is crumbly, and used for mending the roads, and the vesicular trap near 

 Hartford, (see Am. Jour. Vol. XV 11, No. 1,) would in all probability answer the 

 same purpose, and it may be found of the same character in many other places in 

 our trap regions. Th more vesicular, and the more decomposed it is, the better, 

 because it is the more easily pulverized by calcination and grinding. 



I) Extensively used in Pennsylvania, and highly valued. J. G. Not much used 

 in New England. 



