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Previous Next The best candle and soap tips online! TECHNICAL TREATISE ON SOAP AND CANDLES. THE FABRICATION OF SOAPS. 263 100 kif. (220 100 kg. (220 lbs.) of the IDS.) of the Specific Degrees Contents lye (in the Specific Degrees Contents lye (in the gravity. Baume. of soda. margin) sa- gravity. Baume. of soda. margin) sa- ponify fats. ponify fats. 2.95 70 77.8 720 kg. 1.40 41 29.0 270 kg. 1.85 66 63.6 596 ' 1.36 38 2G.0 242 ' 1.72 60 54.8 498 ' 1.32 35 23.0 224 ' 1.63 56 46.6 431 ' 1.29 32 19.0 168 ' 1.56 52 41.2 381 ' 1.23 27 16.0 149 ' 1.50 48 36.8 34G ' 1.18 22 13.0 121 ' 1.47 46 34.0 314 ' 1.12 16 9.0 83 ' 1.44 44 31.0 287 ' 1.06 8 4.7 44 ' The fats and oils and the fatty acids as they are received by soap manufacturers, are usually in a condition for immediate use, but occasionally there may be impurities of such a character that they will require to be removed before they are made into soap. If they are merely foreign substances a melting and straining may prove sufficient, or there may be adulterations. This falsification we have pointed out and given some tests for in another section; should the tallows, greases, or oils prove very impure the)' can be improved very much by melting to about 40° C. (104° F.), and adding about two per cent, of strong alkali, say 38° B., stirring gently at this temperature for about a quarter of an hour and then allowing to rest and cool. The impurities will fall to the bottom, and the purified grease can be removed therefrom. It is generally conceded, and in our judgment very truly, that there is no oil or fat, though in itself containing several constituents, which used alone makes a faultless soap. Thus tallow or curd soap becomes in drying too hard and almost insoluble, and so with olive oil soap, which has the same property, and on the other hand, soaps made with the drying oils (linseed, poppy, etc.) are too soft and cannot be made sufficiently hard for use as solid soaps, and are consequently mostly made into soft soaps with potash lye, which, by its hygroscopic property, always remain soft and when exposed to the air absorb water and are constantly getting softer. So that knowing the different properties of the fatty bodies with their behavior when combined with the alkalies, it is necessary so to mix the different oils and fats, and in such proportions that considering the different properties of each, by judicious mixture, may be produced a soap having properties suitable for its intended uses. The mixtures of the different ingredients will be given when we discuss the manufacture of each kind of soap and with them several formulas if necessary. In making soaps by boiling with an open fire, with steam, or surcharged steam, or by whatever appliance or methods the manufacturer may possess, it is necessary in the first place to determine the proper proportions. According to the information already given as to the equivalents for the fats, we suppose that 50 kilog. (110 lbs.) pure fat (which must not be mixed with cocoa-nut oil) demand about 6 kilog. (13.2 lbs.) caustic soda or 8.5 kilog. (18.7 lbs.) caustic potash. This is indeed somewhat in excess of the real necessity, but a little surplus is not injurious, as the lyes are seldom perfectly free from carbonate, and carbonated alkali does not easily combine with neutral fats. On this supposition, we will answer the question, How many kilogrammes of fat might be saponified by 1000 litres (265 gallons) of a soda lye of 20° B. = 1.163 specific gravity = 10.879 per cent.? 1000 litres weigh 1163 kilog. (2559 lbs.); with 10.879 per cent, soda, the same contain 126.5 kilog. (278.3 lbs.) caustic soda; since according to our supposition 6 kilog. (13.2 lbs.) of this 50 kilog. (110 lbs.) fat saponify, hence 126.5 kilog. saponify 126-5 y 50 = 1054.2 kilog. (2319 lbs.) fat. If, on the other hand, we have 1000 litres (265 gallons) potash lye of 20° B. or 1.163 specific gravity, which according to the table (heretofore given) contains 15.842 per cent, potash, and suppose, that 50 kilog. (110 lbs.) fat require 8.5 kilog. (18.7 lbs.) for saponification, then those 1000 litres (weighing 1163 kilog.) contain 184.2 kilog. (405.24 lbs.) potash and , 184.2 x 50 hence - 8.5 saponified. 1083.5 kilog. (2384 lbs.) fat would be 264 TECHNICAL TREATISE ON SOAP AND CANDLES. THE FABRICATION OF SOAPS. 265 Although in the two preceding examples we have supposed the quantity of the lye according to weight, yet it is more convenient for all operations on a larger scale to measure the liquids instead of weighing them. But the proportions thereby become the more varied the stronger the lyes are. Though 500 cubic centimetres (16.9 fluid ozs.) water weigh also \ kilog. (1.1 lbs.), yet 500 cubic centimetres of lye weigh so much more than \ kilog., as this lye is stronger. It is therefore easier and more to the point in question to give the contents of a lye as to its value of caustic alkali, according to its measure than its weight. The figures in the tables as to the contents of the lye relate, however, to weight proportions; but they can be easily changed into volume per cent, by multiplying the former by the specific gravity of the lye. In the preceding examples, there would hence be in the case of soda of 10.879 weight per cent. 12.67 volume per cent., and of 15.842 weight per cent, potash, we would have 18.42 volume per cent.; hence in 1000 litres (265 gallons) are contained 126.5 kilog. (278.3 lbs.) soda, or 184.2 kilog. (405.24 lbs.) potash, the same as above. The measuring method at once commends itself for this reason, because we obtain directly by the investigation of the lye the volume per cent. If in this manner the supply of lye is made the issue for determining the quantity of a boiling, we will never be in a quandary on account of the want of lye during the operation of boiling. That we may also proceed in a reversed way, as soon as we are,sure of having a sufficient supply of lye, and as soon as we are acquainted with the strength of the same, and how much of this lye is required to saponify, for instance 500 kilog. (1100 lbs.) fat, will thus become obvious. Supposing it is intended to make a boiling of 375 kilog. (825 lbs.) fat by means of soda, then we would need of pure lye, which contains 6 percent, caustic soda for each 50 kilog. (110 lbs.) fat 100 kilog. (220 lbs.), and hence for those 375 kilog. fat 750 kilog. (1650 lbs.) of this lye would be required. "We use for these calculations the tables of Perutz, which we have given on pages 259 and 261, and, for the sake of convenience, we have here also added the weight of potash or Previous Next
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