566 



DETAILS OF CONSTRUCTION. 



Dr Urtfs asphalt consists of boiled coal- 

 tar mixed with powdered chalk or bricks, 

 and is said to be nearly equal to the 

 French. 



Asphalt is found natural in some parts 

 of France, and has been long used in that 

 country for a variety of purposes. It is 

 now made artificially in England, and 

 equally good. The following is the pro- 

 cess : " Eighteen parts of mineral pitch, 

 and eighteen of resin, are put into an 

 iron pot and boiled for a little ; after 

 which sixty parts of sand, thirty of small 

 gravel, and six of slacked lime, are to be 

 added. For walks, ordinary floors, or the 

 bottoms of tanks, when the surface is dry 

 and made level, the mixture is laid on in 

 a boiling state to about the thickness of 

 2 inches. For barn-floors or flat roofs it 

 is laid about one-third thicker. This is a 

 cheap and durable covering for the bot- 

 toms of tanks, but it is unfit for the sides, 

 as it can hardly be laid on perpendicular 

 surfaces, from its tendency to run. The 

 objection to asphalt for roofs is, that it is 

 apt to turn soft by the sun, and hence 

 becomes unfit to walk upon. This pli- 

 ancy when heated, however, renders it 

 useful for other purposes. That kind 

 known as Seyssel's asphalt, for example, 

 although made in straight pieces, and in 

 that state often used for edgings in flower 

 gardens, when slightly heated can be bent 

 to suit the curves of the walks, and the 

 turns at their angles. 



In using any of the varieties of Roman 

 cement, it is of the very first importance 

 that it be fresh from the manufactory, or 

 that it has been kept in a dry cellar or 

 storehouse closely packed in casks, so that 

 the air may not reach it. Hence it is 

 best, when small quantities are only to be 

 used at a time, to purchase half or quarter 

 casks ; for after a cask is once opened, the 

 air soon spoils the contents. The work 

 to which it is to be applied should be 

 sound, and secure against settlements. 

 Before laying it on, the wall should be 

 well wetted with water. One-third clean- 

 washed river sand is to be mixed with the 

 cement in small quantities at a time ; 

 hence it is proper to have a person mix- 

 ing the cement while another is laying it 

 on. Cement should in all cases be finished 

 in one coat, and not in two or three, as 

 plasterers do theirs ; for all additions to 

 the first coat are certain to come off with 



the weather. For tanks or cisterns the 

 cement should be allowed to become quite 

 dry, and then get three coats of boiled 

 linseed oil and turpentine, which should 

 also be allowed to dry, after which the 

 water may be let in. It is of import- 

 ance that the work be done during sum- 

 mer, if possible — never during frosty 

 weather. 



The Portland cement is an excellent ma- 

 terial for lining tanks and cisterns, and 

 for other hydraulic purposes. 



Lusors cement. — Under this signature a 

 correspondent in " The Gardeners' Chro- 

 nicle " recommends the following cement 

 as excellent in the formation of aqueducts 

 for conveying water. Flooring-tiles are 

 set in the following — viz., 1 cwt. whiting, 

 2 quarters 18 lb. rosin, 18 \ lb. of brim- 

 stone, 9 lb. tar. 



Austin' l s stone-coloured cement is excellent 

 for covering old defaced walls, brick-built 

 parapets to imitate stone, and also for 

 tanks and water-cisterns. One bushel 

 will, if laid on at the usual thickness, 

 cover 40 superficial feet : it requires the 

 same quantity of sand and water as Ro- 

 man cement, and is laid on with as great 

 facility. 



Francis Anson 9 s Parian cement, used 

 as a stucco, cannot easily be distinguished 

 from statuary or Parian marble. It is fit 

 for all the purposes of that beautiful ma- 

 terial, and does not crack, warp, or efflo- 

 resce in any degree. It is adapted to 

 encaustic work, fresco, imitation of mar- 

 ble, &c. It sets readily, so that even 

 when applied to new or damp walls, they 

 may almost immediately be polished, 

 painted, or papered. It is altogether an 

 excellent cement for in-door work. We 

 have no certain knowledge of its proper- 

 ties to withstand the weather. 



Water cement is of three kinds. The first 

 is made by calcining and reducing to a state 

 of powder four parts good grey clay, six 

 parts black oxide of manganese, and ninety 

 parts limestone reduced to powder by 

 sprinkling water on it. The whole being- 

 well mixed is fit for use. The second con- 

 sists of 1 cwt. of fine clean sand, 1 qr. quick- 

 lime in powder, 14 lb. bone ashes. When 

 to be used, beat the mixture up quickly, 

 using water to bring it to the desired 

 consistency. The third is composed of 

 fifteen parts of white iron ore, (man- 

 ganese iron ore,) eighty-five parts lime. 



