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Previous Next The best candle and soap tips online! 363 362 TECHNICAL TREATISE ON SOAP AND CANDLES. Determination of Soap as to Admixtures.—To enhance the weight and quantity of soaps, they are frequently mixed with cheap, grainy bodies, such as clay, chalk, silicic acid, barytes, starch, etc. These substances remain—by treating the soap with strong alcohol—as a residuum, and may then be, as to their nature, further investigated. If the residue is boiled in water, and a thickish liquid is produced, which can be colored dark-blue by one or a few drops of tincture of iodine, then starch is present. If the liquid be strongly alkaline, it must, before adding iodine solution, be neutralized by acetic acid. To determine whether lime, silicic acid, or clay is in a soap, the residue is treated with muriatic acid, and evaporated over a water-bath to dryuess. If silicic acid be present, this remains as a grayish, coarse powder. Clay is present in the liquid, if it precipitates with ammonia to a glutinous substance, which easily dissolves in caustic soda-lye; and if chalk be present, carbonate of lime is produced by the precipitate obtained of the filtered liquid. Oxalic acid produces a white precipitate of oxalate of lime. The various kinds of soap have often been treated as to their compositions or combinations, and from these analyses is learned how much the soaps which are found in commerce differ from each other. We annex some of these analyses below. Moreover, it also appears, as if in these investigations and experiments lime and dolomite bad not received that attention which they deserve as ingredients of a soap; since none of these analyses mention these minerals as ingredients of soap. And yet it is doubtful if there exists a soap in which they are not present. And in such a case, we may surely suppose, that they are present as sebacic acid salts, forming a portion of the sebacic acids. _» s S2 •SS Wo2 CQOQ t3 CC fi ocooocs M OI ^1 o H I!!!!! f\ 00 i> O O 1O od od d oo TiJ 00(0^00 s 5= cd co co' IH •5 = % kills i^i^S -- *— u ^ p 2 2 5 « 2 2 2-= £-53 g I o w o o o6 co i> LO -* ?* o TJI 5 o =S « 3 O . ?a 03 O "c ^ p. g.c3 05 is 08 o C O m m „ a e ^ nj CJ ^ ED'S ' "3 e Ill O C ZJ g to p- § CO C '3 o 03 o & o a J5 0 364 TECHNICAL TREATISE ON SOAP AND CANDLES. SOAP ANALYSIS. 365 Valuation of Soaps.—The value of soaps is determined generally, according to their contents of neutral fats or sebacic acids. Although soaps with a certain excess of free or carbonated alkali take better hold, that is, act stronger for the removal of dirt, it must not be overlooked that the free alkali not only hurts the hands, but also the textile fibres of the articles washed. For this reason, since soaps seldom are in the market with excess of fat, the sebacic acid value of a soap may be considered the correct rule and measure for the value of a soap. This however is subject to a limit, in so far, as the equivalents of the sebacic acids are somewhat varying, so that equal weights of various sebacic acids, require various weight proportions of alkali, in order to be changed into neutral sebacic salts. If in this manner the Grain (curd) and Paste (cold) soaps are compared with each other, they correspond (if the greatly filled soaps are ex-cepted), in regai-d to their value of neutral sebacic acid soap, the former to the latter approximately as 15 : 11, and in regard to their value of sebacic acids as 10 : 7. In commerce the prices of grain soaps correspond approximately to the cold soaps, = 7:6. According to the sebacic acid—and sebacic acid soap value, the prices should compare as 8 : 6, and we lind hence, that the cold soaps, in comparison with the grain (boiled) soaps, are sold too high. If despite this in modern times the use of cold soaps has overtaken that of grain soaps, the reason of this is partly found in the fact, that the cold soaps, by dint of their contents of cocoa-nut oil, foam very much, on which property a certain value is placed, and for the reason that it is really thought they are cheaper; for the common consumer, who is not in a position to investigate or examine a soap more accurately, is constrained to regard such external, and in this ca3e deceptive signs, as firmness and good frothing are. On the other hand, it has also happened that wool-washing establishments, whose demands for soap amounted to several thousand pounds per week, very soon made the ob-Bervation,tbat they used ^ to i more of a good cold soap than of an equally good boiled soap. The proportion was also Previous Next
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