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Home > '5 o g^ ityof fats....
Previous Next The best candle and soap tips online! '5 o g^ ityof fats. ill I ft- => arts i of and a &< % t "_ si! rt a *J "S £ K- T. S S'S i'S US a: Illl The 100 The ! con we soa •^ S ci © ° ? 0.93 0.46 3.13 4.85 97 3 5 U 4.65 31.30 48.50 69 31 6 5.58 37.56 58.20 63 37 7 n G.51 43.H2 67.90 57 43 8 n 7.44 50.08 77.60 51 49 9 a 8.3 7 56.34 87.30 44 56 10 9.30 62.GO 97.00 38 . 62 11 w 10.23 68.86 106.7 32 68 12 (i 11.16 75.12 116.4 26 ' 74 13 u 12.09 81.38 126.1 20 80 14 u 13.02 84.64 135.8 13 87 15 (( 13.95 93.90 145.5 7 93 Determination of the Amount of Rosin.—Pure rosin soaps do not generally exist, and it would be easy if such were the 360 TECHNICAL TREATISE ON SOAP AND CANDLES. SOAP ANALYSIS. 361 case to distinguish the rosin soap from a fat soap. On the other hand the determination of the amount of rosin in a soap, particularly if the point in question is the investigation of an imitation, is very often of great importance, in order to find out the accurate composition of such a soap, to which as is self-evident the determining of the amount of rosin contained in such an imitation belongs. There are several methods, according to which the quantity of the rosin contained in a soap can be determined. Chemistry, however, must confess that it has not yet succeeded in finding a ready technical method. The following method, which furnishes reliable results, originated with Sutherland. According to this, the soap is cut up into small pieces, weighing a certain quantity, for instance 33J grammes (1.17 ozs.) accurately, and pouring over it, in a porcelain saucer, some strong commercial muriatic acid. The saucer is covered with a glass plate, and heated over an alcohol flame until all soap pieces are perfectly dissolved and decomposed, and the sebacic acid with the rosin floats above. Now 133J to 166| grammes (4.67 to 5.83 ozs.) warm water are added, and the saucer allowed to cool off. The now congealed fat-cake, thereupon, is carefully taken off", and can be already judged by its appearance, whether rosin is contained therein, or not. It is remelted with warm water, in order to remove all adhering acidy solution, and again cooled off, carefully dried with blotting paper, and melted again without water, until the boiling degree is reached. This is for the purpose of removing the last vestige of water. After cooling off, the fat-cake is placed upon the scale, to ascertain its exact weight. In all these operations, all loss must be carefully avoided. If the soap were a pure fat soap, the fat cake thus obtained, after the deduction of 3.5 per cent, for the hydrate, would be 95.5 per cent, of the originally applied fats, and the latter can be easily calculated. But if rosin be present in the soap, it is found in the sebacic acid cake, and this must now be treated as follows. It is placed in a porcelain saucer, holding about | kilog. (1.1 lbs.) water, pouring strong nitric acid over it. Then it is heated very cautiously until the boiling point is reached. At this moment a violent ebullition will ensue, and thick red vapors will develop. As soon as this occurs, the lamp is immediately removed ; and is placed under it again when the violence of the reaction has ceased. It is now left to boil a few minutes, while frequently stirring with a glass rod, adding now and then small portions of nitric acid, until no more red vapors develop. All these operations are performed in the open air, on account of the development of acid vapors. It is again cooled off", removing the cake of sebacic acid, which floats upon the strong acidy and deeply colored acid of the rosin, washing it off, and re-melting it in nitric acid. After cooling off it is finally dried, and once more melted, by itself at a gentle heat, until no more acid vapors appear, and then left to congeal. What remains is pure sebacic acid, and the difference in weight (the loss) against the weight of the cake first weighed, indicates the quantity of the rosin. The latter is thus obtained immediately, but the quantity of the pure sebacic acids found must, as was stated before, be calculated after the reduction of the neutral fat. This is done by deducting 4J per cent., corresponding to the glycerine present. If the soaps ha\7e been made with oil, i. e., liquid fats or oleic acid, then the separated sebacic acids do not congeal easily into a solid cake, and it would then be difficult to weigh them accurately. In this case also the condition of an exactly weighed small portion of white dried candleshop.com/cgi-bin/affiliates/clickthru.cgi?id=soforreal">wax serves to melt it together, in order to obtain a firm cake, which can be weighed without trouble, and from the weight of this, in order to ascertain the quantity of the sebacic acids, the weight of the added candleshop.com/cgi-bin/affiliates/clickthru.cgi?id=soforreal">wax is deducted. Of this mode of determination we have to remark, that too large a surplus of nitric acid must be avoided, nor should the same act upon the sebacic acid cake any longer than is necessary, since according to Heintz, a small portion of stearic acid or palmitic acid becomes easily oxydized. SOAP ANALYSIS. Previous Next
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