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Home > CHEMICAL EQUIVALENTS APPLICABLE TO SOA?.
Previous Next The best candle and soap tips online! CHEMICAL EQUIVALENTS APPLICABLE TO SOA?. 153 SECTION VI. THE CHEMICAL EQUIVALENTS APPLICABLE TO SOAP. By equi7alents the chemist understands—to maintain the simplest example—the certain equal values of the different acids, which are requisite to produce with a certain amount of weight of a base a solid chemical combination ; just i;i the same manner as if we chose a certain acid for a departure. In the first case, we would, for instance, require for 47.11 parts in weight of potash, 40 parts weight of sjlphuric acid, 54 parts weight of nitric acid, 36.4 parts weight of muriatic acid, 75.0 parts weight of tartaric acid, 51 parts weight of acetic acid, etc., all these acids supposed to be free from water, in order to produce the corresponding neutral salts of these acids with potash. The acids are therefore according to the stated par;a weight equivalent. To neutralize 40 parts_ in weight of sulphuric acid 47.11 parts weight of potash, 31.0 parts weight of soda, 17 parts weight of ammonia, 28 parts weight of lime, 76,5 parts weight of barytes, etc., would be requisite. Here the bases are according to the stated weight amounts equivalent In what manner these calculations have been ascertained does not pertain to this treatise. Entirely in the same manner correspond the various seba-cic acids, which are applied in the making of soap, respecting their combinations with the oxide of glyceryl, that is. the flit a themselves; and it would according to our conviction be a very great progress in the production of soap, if here too, as is done in the making of salts from one acid and one base, fur the fixed amount of sebacic acid, the fixed amount of alkali wsuld be applied. Many will probably shrug their shoulders in a contemptuous manner, when reading this proposition, and state, that the correct proportions could be easier gained by experiment. But the author has been tvit- ness to the fact as to what this experimenting means: If for instance a want of alkali ia ascertained, we add at random —since every support for a correct determination ia wanting —a portion of lye. By the nest test we find that the soap has too much "bite," i.e., an overplus of alkali, which is likewise to be abated at random, by adding more fat. Thus it changes alternately to and fro, till at last the true proportion is deemed to have been found. Thus comes the trouble that we finally do not know what yield of soap aiay be calculated upon, for as a rule the fat which is added for correction is never weighed into trie kettle, and thus all control of the work ceases. TSy using the equivalents all uncertainty vanishes at once, and the corresponding necessary amounts of fat and alkali can be ascertained with the same security in advance, as if the point in question had been to neutralize a certain quantity of alkali by sulphuric or nitric acid. The other is even easier, since a little overplus of alkali in the case of soap does not matter, and by natron soap is removed by the cutting of the pan with salt, bat in case of soft soap3 it becomes very necessary. The advice which we here desire to impart to soap manufacturers is not merely founded upon tests made on a small scale, but upon experience gained by experiments in the working up of fats into soaps on an extended scale. It is the result of an experience which is frequently mt.de in every-day life, that even errors are upheld with the greatest stubbornness by those who ear-not be compelled to learn anything new. In our case it is for most of those concerned the difficulty of determining the strength of the lyes. And yet nothing is easier than this operation; but even if it were more difficult and required more time, these would hardly enter into consideration in comparison with the loss of time and other diaturbances which are connected with the correction of erroneous proportions between fat and alkali. The equivalents of fats which are used in making soap are among themselves not so different that in practice much consideration need be shown regarding this, although it may be somewhat different with the soaps which are manufao- 154 TEOHNICAL TREATISE ON SOAP AND CANDLES. CHEMICAI, EQUIVALENTS APPLICABLE TO SOAP. 155 tured from the same. The differences are in fact so insignificant, that, besides a small loss in alkali, it would not cause the least disadvantage, if for that fat, which for its saponification requires the least amount, juat as much alkali were taken, as if we had to do with a fat, which for its saponification required the greatest amount of alkali. "What alone is to be the matter of consideration in this case is, from the outstart, the requisite quantity of alkali, but on no account a surplus, or, in other words, it is to be ascertained in advance, how much fat of a given weight, to the lyes on hard, has to be taken to obtain the most possible neutral soap, so that every correction, be it of fat or be it of alkali, becomes superfluous. The neu:ral soaps contain for 1 equivalent of sebacic acid 1 equivalent of caustic potash, and according to this proportion the quantity of alkali must likewise be measured when, in place of sebacic acid, the neutral fata are to be saponified. Inasmuch as we now know the composition of the neutral fats—they are almost without exception combinations of 3 equivalents sebacie acid with 1 equivalent of glycerine, the former composed one-half of oleic acid—so their equivalents too may be easily calculated, and we find thus the threefold equivalent For Tallow: Tristearin . . C1M HII0 O12 Triotein . . . C,,, H,n, O,, Since these figures represent the threefold equivalents of the respective oils, we hence need for their saponification 3 equivalents of alkali; of natron 9.3 parts in weight, and of potash 104.76. For the equivalent weights, for instance 100 kilogrammes (220 lbs.), of those fats and of oleic acid, we would therefore require— For Tallow: 10.50 kg. (33.1 lbs.) soda or 15.87 kg. (84.J1 His.) potash " Palm Oil: 11.00 " (24.2 tl ) " 16.66 ". (36.65 " ) " " Cocoa Oil: 12.44 " (37.37 " ) " 18.82 " (41.40 " ) " " Oleic Acid: 10,53 " (38.14 " ) "" 13.92 " (35.03 " ) " Whereas a Bmall overplus of alkali is not only not harmful, but really enhances the Baponifieation of the fate, we may without any hesitation to 100 parts of neutral fat take 12,0 or 12.5 parts soda, and for soft soaps 16 or 17 parts of potash, of which it is always demanded that they "bite" strongly. An addition is allowed of 2 or 3 of fluid as an overplus; if the soap contain cocoa-nut oil, proportionately more. From the above it evidently follows that a fat furnishes the more soap, without regard to the changing-contentB of water, the more alkali the respective sebacic acids demand for their saturation or eaponification. The most productive according to this is cocoa-nut oil; the least soap furnished is by till low. i0T 0)t = 887 For Palm Oil: Tripalmitin CK3 HM Oia Triolein . . C1M II1W Olt s4 _ C] TT O — ' ^loa ^loi ^12 — For Cocoa-:iut oil: Trilaurin C73 HH Ol2 Trirayristin C90 HM O1Z Triolein . . OIH H104 OH Previous Next
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