AMERICAN INSTITUTE. 473 



Burn this piece of white marble, and one part of it with ten parts of the 

 lime makes good mortar. 



Prof. Hedrick. — The finer the particles of snnd are, the more surface 

 do they afford for contact with the lime, and thus a greater cohesion. 



Some conversation on chemistry ensued touching this subject. 



Mr. Meigs. — The Italian plaster figure maker, in this building, has just 

 completed a model parfifion ivall of plaster, the interior composed of 

 many strong iron wires interlaced and enveloped in the plaster. 



Prof. Mason. — The chemist deals with equivalents. , 



Prof. Hedrick. — But it will be a nice question in the process of the 

 silicate and sand in the time of induration. Analysis might determine the 

 equivalent for that lime '''■pro hac vice.'''' 



Prof. Mason. — The pulverization of the sand, to make good mortar, 

 seems a point gained. It ought to be investigated. 



Mr. Wilmarth.— Grind the sand fine, make the mortar, press that into 

 models, blocks, lintels, columns, capitals, &c., &c. A building can be 

 made thus that would grow harder the longer it stands. 



Mr. Meigs — As the shell rock buildings of the island of Bermuda do, 

 Evei-y additional century only gradually converts them into pure hard 

 limestone, so that from what I observed of one-tenth of an inch skin of 

 hard limestone formed on the outside of a house about 100 years old, in 

 city of St. Georges, Bermuda, a wall two feet thick may be converted 

 wholly into the same hard limestone in ttoenty-four thousand years ! or at 

 any rate, if that house had been built by our great forefather, Adam, it 

 would now have a hard skin of six inches thick on it. 



Mr. Veeder. — As in some buildings or parts of buildings we require 

 hydi'aulic lime, and wherever moisture is to be prevented access. I tried 

 experiments as follows : Requiring in my business large tight vessels to 

 hold oils, I constructed one cistern of six thousand gallons, out of Am- 

 sterdam (N. Y.) lime, and Roman cement as a lining to it. I made one of 

 loose field stones and cement, lined same way. They hold oils perfectly. 

 The last cistern holds fifteen hundred gallons, and the construction of it 

 cost me only thirty dollars. I had an iron band around the upper rim, 

 English authors recommend hard burned clay pulverized as a component 

 of mortar for strength. I built an outer wall, and to the plaster for out- 

 side added some soft soap, which, when intimately worked into the mortar, 

 formed a very smooth cement and a hard surface. My workmen told me 

 it would crack off. Never mind, said I, put it on ; let it crack off. That 

 coat is now as hard as stone, and no crack whatever. Hard burned brick 

 pulverized is excellent in mortar. I filled cavities in some of my old fruit 

 and other trees full of it, with the field stones imbedded in it. The trees 

 like it, and are fast growing over the entrance. We observe the condition 

 of flint with its bed of chalk, showing the slow conversion of the flint into 

 chalk. Some English builders require a year or two to build a house, 

 believing that this slow mode serves to add strength and duration. 



Mr. "Wilmarth. — I am a builder, and late from England ; I did not dis- 



