The municipal and sanitary engineer's handbook / by H. Percy Boulnois.
- Boulnois, H. Percy (Henry Percy)
- Date:
- 1883
Licence: Public Domain Mark
Credit: The municipal and sanitary engineer's handbook / by H. Percy Boulnois. Source: Wellcome Collection.
127/434 page 107
![heat; this is sometimes used in conjunction with fine sharp clean river sand, but more often with finely crushed stone about the size of peppercorns, and is styled gritted asphalte. As long ago as the year 1838, Mr. F. W. Simms speaks of asphalte mastic from Pyrimont, near Seyssel, and says it may be considered a species of mineral leather *—a very good description of its surprisingly tough, hard, durable and pliant properties. The usual method of the preparation of the mastic is as follows :— According to the amount of bitumen contained in the natural stone, from 5 to 8 per cent, of refined Trinidad bitumen] is placed in a large caldron which is usually provided with agitators driven by steam power ; when this is thoroughly melted, the powdered asphalte is added little by little, the heat being raised to between 3900 and 4800 R, the mixture kept well stirred and cooked for about five hours. It is then turned out into iron moulds, most companies having a special pattern with a trade mark for this purpose. The caldrons generally used contain from \\ to 2 tons of mastic. Some companies in large towns are provided with caldrons on wheels, commonly called Locomobiles, in which case the grit is mixed with the mastic in the fixed caldrons, and the whole mass run out into the locomobiles (which are also pro- vided with agitators worked by an endless chain attached to the axle of the wheels), and transported direct to where the work has to be done. This system, though undoubtedly the best, is not practicable except in large towns ; the more usual * Vide ' Proceedings of the Institution of Civil Engineers,' vol. i. p. 6. f Trinidad bitumen is best, but it has to be refined before it can be used. This is done by cooking it with shale oil, then straining it and decanting it, which is a troublesome and tedious process, and there is great danger of fraud being practised. Good bitumen can be detected by its elasticity and softness when rolled between the finger and thumb, and also by its smell.](https://iiif.wellcomecollection.org/image/b20410244_0127.jp2/full/800%2C/0/default.jpg)
