It is generally believed that the object of adding lime to cane-juice is for the purpose of neutralising an acid, and it is to the reception of this fallacious idea that it is indebted for its long and continued use, and the present backward state of sugar manufacture is attributable: I unhesitatingly assert that, if there be an acid present in the cane-juice, the addition of lime to it will be injurious instead of beneficial. There are only four acids that we could expect to find in cane juice—mucous, saccholactic or saclactic, oxalic, and acetic acids. The three first named of these, however, have never been traced, even in the most minute quantities; and if the latter be present, which, unfortunately, is but too often the case, the addition of lime would only result in the formation of acetate of lime, which is, as I have already observed, an exceedingly difficult crystallisable, very soluble, and deliquescent salt. It has a bitter, saline taste; 100 parts consist of 64.5 acid, 35.5 lime, and it is easily recognisable by its taste in the molasses made from sour cane-juice: so that, supposing the cane-juice sour, every pint of acid present would require nearly half a pound of lime for its neutralisation, independent of the quantity required for the tempering or precipitation of the feculencies contained in it, and would result in the formation of one-and-a-half pound of the above mentioned highly deleterious salt.
Suppose we boil the cane-juice prior to tempering it, we then drive off a great portion of acetic acid, much less lime will be required, and if we could, by filtration or subsidence, get rid of the precipitated feculencies, we should make a tolerably good sugar; but as, under the present plan, we have no means of so doing, the acetic acid, which is forming during the whole process of evaporation (as fermentation still goes on), unites with the lime before it can be dissipated by the heat, and thus not only forms acetate of lime, but causes the re-solution of the precipitated feculencies, thus rendering it necessary to add a fresh portion of lime in the tache, a proceeding always to be avoided, if possible, but generally necessary in boiling down sour liquor. Take a small portion of cane-juice (hot or cold) in a tumbler, and temper it with lime until the feculencies are precipitated and the flakes perfectly visible, then add vinegar by drops, and it will be found that the flakes will speedily disappear and be re-dissolved, showing that lime has a greater affinity for acetic acid than starch, and that, although when added to sour cane-juice, it neutralises the acidity, still that result is a consequence, not the cause, of the application, and is highly injurious. Lime is one of the greatest known solvents of vegetable matter; it dissolves albumen, gluten, gum and lignin, or woody fibre, forming soapy compounds with wax, resin, and, chlorophyle. Ordinary cane-juice contains about three parts of resin to every 100 of sugar, and the projection of a small piece of soap into a tache full of granulating syrup will soon convince any one of the effect likely to result from the presence of that material. Although, by tempering hot, we get rid of a very great quantity of the substances on which lime acts injuriously, a considerable portion of them remain in suspension, the quantity of albumen contained in the cane-juice not being sufficient to carry them all off by coagulation; on the addition of the lime, however, they are entirely dissolved and as the impurities left behind consist chiefly of gluten, the liability of the liquor to ferment is greatly increased by its retention, that being the fermenting principle contained in wheat and other vegetable productions prone to that process.
One hundred parts of Albumen consist of Carbon, 52.88; Oxygen, 23.88; Hydrogen, 7-54; Nitrogen, 15.70. Gluten, nearly same as Albumen.
| 100 parts consist of | Carbon. | Oxygen. | Hydrogen. | Carbon. | Water. | Excess of Oxygen | Excess of Hydrogen |
| Lignin, or Woody Fibre | 51.45 | 42.73 | 5.82 | or51.45 | 48.55 | .. | .. |
| Starch | 43.55 | 49.63 | 6.77 | 43.55 | 56.45 | .. | .. |
| Sugar | 42.47 | 50.63 | 6.90 | 42.47 | 57.53 | .. | .. |
| Gum | 42.23 | 50.84 | 6.93 | 42.23 | 57.77 | .. | .. |
| Alcohol | 51.98 | 34.32 | 13.70 | 51.98 | 38.99 | .. | 9.03 |
| Acetic Acid | 50.22 | 44.15 | 5.63 | 50.22 | 46.91 | 2.87 | .. |
| Resin | 75.94 | 13.34 | 10.72 | 75.94 | 15.16 | .. | 8.90 |
| Wax | 81.79 | 5.54 | 12.76 | 81.79 | 6.30 | .. | 11.01 |
By a reference to the foregoing table it will be easily understood how slight a change in the proportion of the ingredients of any one of the substances contained therein will convert it into an entirely different one. In chemistry we are able, to a certain extent, to imitate the operations of nature; but we must follow in the same course laid down by her; thus, we can convert woody fibre, or sawdust and starch, into sugar, gum, alcohol, and acetic acid; but we cannot convert alcohol, acetic acid, or gum into sugar, starch or woody fibre; and of such importance is a slight alteration of the proportions of these elements—carbon, oxygen, and hydrogen—that the abstraction of carbon from sugar, and the addition of a portion of the prime support of life, vegetation and combustion, oxygen, changes the harmless sugar into the most violent of poisons, oxalic acid, which consists of 26.57 carbon, 70.69 oxygen, and 2.74 hydrogen.
Let us now examine the action of lime on sugar, and we shall find it equally, if not more, injurious than on the other substances. Sugar is capable of dissolving half its weight of lime, by which its sweet taste is destroyed, and it becomes converted into gum; the lime abstracting carbonic acid from it to form a carbonate of lime or chalk. It will be seen by the above table that—
| 100 parts of sugar contain | 42.47 | carbon. |
| 100 parts of gum contain | 42.23 | ditto. |
| Difference | .24 |
So that, if we extract 24-100ths of a grain of carbon from 100 grains of sugar, we convert them into gum. Let us suppose that about two ounces of lime, or say 1,000 grains, remain in solution in a pan, (say 200 gallons of liquor,) those 1,000 grains of lime will require 761 of carbonic acid to convert them into carbonate of lime or chalk, 100 grains of which consist of 56.2 lime and 43.8 carbonic acid. So that 1,761 grains of chalk consist of 1,000 lime and 761 carbonic acid. Now 100 grains of carbonic add consist of 27.53 carbon and 72.47 oxygen; therefore 761 grains will consist of 209.50 carbon and 551.53 oxygen.
Consequently, 1,000 grains of lime will require 209.50 grains of carbon to convert them into carbonate of lime; and as we have seen that the abstraction of 24 from 100 grains of sugar convert them into gum, it follows, that the abstraction of 209.50 grains would have a similar effect on 87,000 grains, or about 15 lbs. of sugar, which, being converted into gum, would prevent the crystallisation of several times its weight of sugar; and this is the cause of the formation of molasses. The loss of sugar is not the only bad consequence of the use of lime, as the greater the quantity of gum in the liquor, the more it must be boiled—the more it is boiled the darker it gets—and the higher the temperature at which the skip is struck, the smaller the grain. The following is a good proof that lime dissolves albumen, and becomes converted into chalk:—Take a spoonful of syrup out of the tache of any estate on which the liquor is tempered cold; it will be found filled with small flakes; these are albumen set free from its solution in the lime by the conversion of the latter into carbonate of lime, and coagulated by heat. It is perfectly possible to temper liquor, so that scarcely any uncrystallisable sugar will remain; but planters do not like this; they must have molasses for the still-house; they could, however, boil low, by which the grain and color would be improved, and plenty of uncrystallised, although not uncrystallisable, syrup would be left to take the place of molasses.
I think I have now fully proved the following facts, viz.:—That the use of lime in sugar-making is not to neutralise an acid; that if acidity be present, the application of lime is injurious; that its action on gluten, albumen, wax, resin, and chlorophyle is equally so; that by decomposing the sugar and forming gum, the quantity of molasses or uncrystallisable sugar is much increased, whereby high boiling is rendered necessary, with its consequent heightening of color and injury to the grain of the produce, and that therefore it is perfectly unfit for the purpose of tempering cane-juice.