K. MECHANICS AND ENGINEERING. 405 



est inventions of the day, in having so many important appli- 

 cations, being used for concrete bricklayer's work, as stuff for 

 plastering, mortar for pointing, stuccoing, etc. It is said that 

 ceilings can be floated immediately after the application of 

 the first coat, and set in forty-eight hours. Bricks can be 

 made of one part lime to eight or ten parts burned clay or 

 sand, pressed in a semi-dry state without burning, and ready 

 for use in about ten days. 3 A, July 8, 5. 



IMPROVED MORTAR. 



According to a recent writer on the subject, it is stated 

 that the disadvantages- of the ordinary kinds of mortar at 

 present in use arise chiefly from their being made of an infe- 

 rior kind of sand, and the great difficulty of obtaining good 

 sand at a moderate price. He therefore suggests an improved 

 material, which requires no sand, and which only needs to be 

 mixed with water. To prepare one ton of this mortar, two 

 hundred and twenty-eight pounds of lime (either quicklime 

 or slacked), seventeen hundred and twenty-eight pounds of 

 slag, and two hundred and twenty-four pounds of calcined 

 coal-shale clay are to be ground by machinery, and when 

 brought to a powder, or a proper degree of fineness, are to be 

 mixed with water, and the mortar will be ready for use. 

 9 A, 1870,104. 



VICTORIA STONE. 



In a communication upon artificial stone made to the Brit- 

 ish Association by the Rev. Mr. Highton, the well-known fact 

 was adverted to that certain forms of natural silica occurring 

 in various parts of Europe, esj)ecially in England and Ger- 

 many, can be dissolved, under proper precautions, even when 

 cold. An important application has been made of this solu- 

 ble silica in the preparation of an artificial stone, which is 

 harder than any natural stone, except the hard granites and 

 primitive rocks. The process indicated for utilizing this con- 

 sists in first making a concrete of any good hydraulic cement. 

 When this is dry it is steeped in an alkaline solution of silica, 

 in which is placed a quantity of free silica. The following 

 chemical process then takes place : the lime in the concrete 

 extracts the silica from the solution, leaving the alkali free, 

 which immediately attacks the free silica, and conveys it in 



