16
38
The analysis of a suitable soap would be as follows:-
Content of real soap
Sodium Carbonate
Sodium Silicate
Free caustic alkali (Na20)
་ ་ ་
Insoluble in Absolute Ethyl Alcohol Hydrocarbons
Salt (NaCl)
Titre*
Moisture
cent.
... not less than 57
per ...not over 25 per cent. ...not over 3.5 per cent. ... less than 0.05 per cent. ... less than 8 per cent. ...less than 20 per cent. ...less than 0.2 per cent. ...33 to 36° C.
...not over 35 per cent.
*Note on
“Titre.”—Titre is the name given to the solidifying properties of the fatty acids in soaps, and is measured in terms of temperature. The titre of the tallow in a soap may almost be said to be a measure of market value as an ingredient. Thus the better quality soaps have a titre at a higher temperature; thus, a shaving soap would have a titre between 48° C. and 49° C. as against 42°-- 45° C. for a high quality toilet soap.
This does not mean that such a soap is the only emulsifying agent avail- -able-the powder called "Rinso" is stated to be highly suitable for the purpose. We are informed that excellent emulsions have been made from the following composition:-
Trinidad Asphalt Cement
(85 to 100 penetration)
Oleic Acid
Caustic Soda
Water
54.50 per cent.
... 085 to 0.90 per cent. 0:39 to 0.65 per cent. ... Balance.
The Trinidad Lake Asphalt Operating Co. Ltd., inform us that they would be very pleased to make tests of any type of soap, or other emulsifying agents submitted, and advise upon their suitability.
For the guidance of Public Work Departments the following are approximate prices (f.o.b. British Port) of the ingredients shown in the specification:
Refined Trinidad Lake Asphalt Flux
Soap
...£7. 19s. Od. per ton.
£9. 0s. Od. per ton. ...26s. to 30s.
per cwt.
These prices would require confirmation and are submitted as a rough guide to enable oversea Engineers to compute the cost of making their own emulsion. The price of soap was obtained from quotations in London, but it is probable that it could be materially reduced if an order for an appreciable quantity could be placed.
METHOD OF PRODUCTION.
A proportion of Refined Asphalt, broken into small chunks, is first melted in the kettle before the addition of the flux, after which the remainder of the asphalt is broken up into the kettle, temperature not being permitted to rise above 150° C. nor to fall below 135° C. until complete blending has been obtained and if a consistency test is to be made it should have a penetration between 85 and 100 degrees when tested at 25° C. under a load of 100 grammes for five seconds. The proportions of flux given above are based on this range of consistency. If a harder or softer base is desired, then, of course, the proportion of flux must be either decreased or increased. Agitation, either mechanical, or by means of a long wooden paddle is desirable.
No comments yet.
Private notes are available after approval.