AMERICAN INSTITUTE. 469 



The committee on "Building materials of the State of New York," ia 

 Professor Cyrus Mason, Tillman, Dwight and Dr. Deck. 

 The Club then adjourned. 



H. MEIGS, Secretary. 



March 16th, 1859. 



Present — Messrs, E-ohert L. Pell, late President of the Institute, Prof. 

 Mason, Prof. Hedrick, civil engineers Tillman, Everitt, Stetson, Haskell, 

 Arts ; Messrs, J ohn Johnson, Seeley, Garbanati, Yeeder, Wilmarth, Fi- 

 nell, Bresiach, Prof. Bowden, Dwight, Leonard, Chambers, Judge Harris, 

 Scoville, Bushnell, Witt, Hon, R. S, Livingston, Alanson Nash, Boyle, 

 Sykes, and others. Fifty-one members, 



Mr. Pell in the chair. Henry Meigs, Secretary. 



The secretary read the following papers prepared by him, viz : 



MORTAR. 



Sand from rivers, where it has been well washed, is far superior to that 

 of land. 



The best mortar of the Greeks and Romans was made two years before 

 it was used. Their reasoning was just. We make it, if we please, as well 

 as they did, but we nse it immediately, and the small qnantity between 

 joints loses its virtue ; or if not ruined by absorption in the porous mate- 

 rial, becomes ultimately pretty strong ; but with the ancients, mortar never 

 used until it was ripe : the materials and mortar became almost one solid 

 mass. The use of metal coags, (as ship builders call them,) to secure the 

 adjustment of walls and of columns, was good, giving much greater strength 

 as it grows older. The gradual hardening of it is owing to slow conversion 

 of the hydrate of lime (slacked lime) into carbonate of lime, (a marble) 

 by absorption of carbonic acid gas from the atmosphere. If mortar dries 

 too soon, the carbonate formed will remain much divided, and never can 

 afterwards become adhesive. If mortar be kept long moist and exposed to 

 the air, the carbonic acid gas acts slowly but incessantly on the lime, and 

 finally converts It into an almost crystalline carbonate. The proportions 

 of sand and lime in mortar should be one bushel of lime to a bushel and an 

 half of sand. The lime should be thoroughly burned. 



Lime stone, which contains considerable silica and alumina, form what 

 we term hydraulic lime. The mortar made with it sets quick cither in or 

 <mt of IV at er, Parker cement is such, and sets in fifteen minutes. 



The Chairman mentioned experiments tried by him on mortar. The 

 sand and lime intimately mixed di-y and left undisturbed in heap for two 

 years, forms an excellent mortar. The same constituents buried in mass 

 in the earth for two years also produced good mortar, far superior to that 

 recently made. This must be due to chemical action, which continues 

 after its use in the building, until ultimately the union of the lime and sand 

 S^coiaes as hard as the stones or bricks which it binds together. 



