Alkalinity

“ In modern chemistry alkali is a general term used for compounds which have the property of neutralizing acids, and is applied more particularly to the highly soluble hydrates of sodium and potassium and of the three rarer ``alkali metals,'' caesium, rubidium and lithium, also to aqueous ammonia. In a smaller degree these alkaline properties are shared by the less soluble hydrates of the ``metals of the alkaline earths,'' calcium, barium and strontium, and by thallium hydrate. An alkali is distinguished from an acid or neutral substance by its action on litmus, turmeric and other indicators. ”

“ The fixed alkalis are of vegetable or mineral origin. When in a solid form, they both melt with a moderate heat, and uniting with earthy substances, make glass. With an intense heat they are volatilized.
Vegetable alkali is procured by burning plants, and lixiviating the ashes; a purer kind by the burning of tartar, hence called salt of tartar; but the purest of all is got by the deflagration of nitre; the charcoal uniting with the acid as it assumes the form of dephlogisticated air, and the alkali being left behind. ”

“ Commonly when we join two bodies together, their acrimony or attraction for other substances becomes immediately either less perceivable or entirely insensible; altho' it was sufficiently strong and remarkable before their union, and may be rendered evident again by disjoining them. A neutral salt, which is composed of an acid and alkali, does not possess the acrimony of either of its constituent parts. It can easily be separated from water, has little or no effect upon metals, is incapable of being joined to inflammable bodies, and of corroding and dissolving animals and vegetables ”

“ Alkalies form one of the classes of saline bodies, and are of three kinds: the vegetable alkali—kali, or potash,—the mineral alkali—soda, or natron,—and the volatile alkali, or ammonia. Alkalies are distinguished by their changing blue vegetable colours to a green, and yellow to orange; by combining rapidly with acids, and forming with them neutral salts—and by rendering oils miscible with water. Vegetable and mineral alkalies, not being evaporable, except in a high degree of heat, are termed fixed: and ammonia, being evaporable in a low temperature, obtains the name of volatile alkali.—White. ”

“ Yet, if to a compound of quick-silver and the nitrous acid, we add a compound of the fixed alkali and the vitriolic acid, or a vitriolated tartar, and digest the mixture with a strong heat, the vitriolic acid does not remain with the alkali, but is joined to the quick-silver which it attracts more weakly, composing with it a turbith mineral; while the alkali is joined to the nitrous acid which it likeways attracts more weakly than it does the vitriolic, and is converted into salt-petre. ”

“ Like them, however, it dissolves ice, and deprives alum, and some other saline substances, of the water which they contain. United with fixed air, it makes the concrete volatile alkali; with marine acid air, the common sal-ammoniac; and with water, the caustic volatile alkali.
The electric spark, or a red heat, converts alkaline air into three times its bulk of inflammable air; and the calces of metals are revived in alkaline, as well as in inflammable air; but there remains about one-fourth of its bulk of phlogisticated air. These facts shew that alkaline air consists chiefly of phlogiston. ”

“ What is free alkali? Why should any soap injure fabrics? What makes a soap "strong"?
The answer to all these questions is that there are some substances called bases, which are the opposites of acids, and some of which are as powerful as acids. Lye, ammonia, caustic soda, and baking and washing soda are common bases. The strong bases, like lye and caustic soda, are also called alkalies. If you want to see what a strong base—an alkali—will do to "the most delicate of fabrics," and to fabrics that are not so delicate, for that matter, try the following experiment:
Experiment 108. ”

“ The standard solution of semi-normal "alkali." The best alkali for general purposes is ammonia, but, since it is volatile (especially in strong solutions) , it is best to make it of half the usual strength, or semi-normal. One litre of this will contain 8.5 grams of ammonia (NH3) , and 100 c.c. of it will just neutralise 50 c.c. of the normal "acid." Take 100 c.c. of dilute ammonia and dilute with water to one litre. Run into a flask 50 c.c. of the standard "acid," tint with methyl orange, and run in from a burette the solution of ammonia till neutralised. Less than 100 c.c. ”

“ An alkali deprived of all impurities, being thereby rendered more caustic and violent in its operation. This term is usually applied to pure potash. Fixed alkali: An alkali that emits no characteristic smell, and can not be volatilized or evaporated without great difficulty. Potash and soda are called the fixed alkalies. Soda is also called a fossil or mineral alkali, and potash the vegetable alkali. Volatile alkali: An elastic, transparent, colorless, and consequently an invisible gas, known by the name of ammonia or ammoniacal gas. The odor of spirits of hartshorn is caused by this gas. ”

“ Now, as the Fixed Alkali, found in the ashes of unputrefied plants, is only the most fixed part of their earth and of their Acid, closely united together by the igneous motion, it is not surprising that, when all the Acid, with a part of the earth, is subtilized and volatilized by putrefaction, no Fixed Alkali can be found in the ashes of putrefied Vegetables. The alteration which the Acid suffers by the putrefactive motion is, in my opinion, the greatest it can undergo, without being entirely destroyed and decomposed, so as to be no longer a Salt. ”

“ Alkali should naturally be present to neutralize it, for it is unnatural to have a large excess of acid in the secretions, or any excess in the blood. We thus administer alkalies on the restorative principle. They are not always excreted; but whether excreted or not, they tend to render the secretions neutral and alkaline by increasing the quantity of basic matter in the system. Alkalies being more stable than acids, and being more invariably secreted by the kidneys, it is more easy to render the urine alkaline than to make it acid. ”

“ To prove that on this occasion, as well as on all others, where unputrefied bodies yield a Volatile Alkali, this salt is the product of the fire, we need only observe, that in these distillations it never rises till after some part of the phlegm, of the acid, and even of the thick oil of the mixt, is come over; which never is the case when it is formed beforehand in the body which is the subject of the operation, as it is in those which have undergone putrefaction: for this salt, being much lighter and more volatile than those other substances, rises of course before them in distillation. ”

“ The second Volatile Alkali which rises in our distillation, but not without a very strong degree of fire, and at the same time with the last thick Oil, seems to be a production of the fire; for if it were already formed in the mixt, as the other is, it would rise with the same heat, and at the same time, being equally volatile. It is not impossible, however, that it may exist perfectly formed in the plant; but, having contracted an union with some Acid, and therewith composing an Ammoniacal Salt, it may by that means be hindered from rising so readily as is agreeable to its natural volatility. ”

“ Alkali, al′ka-li, or -lī, n. (chem.) a substance which combines with an acid and neutralises it, forming a salt. Potash, soda, and lime are alkalies; they have an acrid taste (that of soap) , and turn vegetable blues to green:—pl. Al′kalies.—n. Alkales′cency, tendency to become alkaline.—adj. Alkales′cent, tending to become alkaline: slightly alkaline.—n. Alkalim′eter, an instrument for measuring the strength of alkalies.—adj. Alkaline (al′ka-līn, or -lin) , having the properties of an alkali.—n. Alkalin′ity.—v.t. Al′kalise, to render alkaline:—pr.p. ”

“ From this experiment we learn, that acids attract the [Pg 21] calcarious earths more strongly than they do the earth of alum; and as the acid in this salt is exactly the same with the vitriolic, it composes with the calcarious earth a neutral substance, which is very difficultly soluble in water, and therefore falls down to the bottom of the vessel along with the earth of alum which is deprived of its acid. The light cloud formed by the alkali proceeds from the minute portion of the calcarious compound which saturates the water. ”

“ The alkali which commonly exists in artificial manures is soda, and when alkaline salts appear in any analysis, they must be assumed to consist almost entirely of that substance generally in the form of common salt, and be valued accordingly. Sulphate of lime and organic matter though abundant constituents of most manures, add but little to their value, and it is a moot point whether they ought to be taken into consideration, although most persons allow a small value for them. ”

“ An excess of alkali is present, however, as the solution has an alkaline reaction. Each “heaping teaspoonful” (which was found to be about 4.85 Gm.) contains about 0.044 Gm. of caffein (the manufacturers claim 0.0648 Gm. per heaping teaspoonful) . As taken, Alkalithia, therefore, represents caffein in a solution of alkali tartrate, citrate and bicarbonate containing free carbonic acid. If it is assumed that all of the tartrate and citrate in Alkalithia is converted into carbonate in the organism, a “heaping teaspoonful” of Alkalithia would represent about 2.9 Gm. of sodium bicarbonate. ”

“ To Basil Valentine we are moreover indebted for the discovery of the Volatile Alkali, and of its preparation from Sal Ammoniac; he also first used mineral acids as solvents, and noticed the production of Ether from Alcohol; he seems also to have understood the virtues of sulphate of iron, for he says, when internally administered, it is tonic and comforting to a weak stomach, and that externally applied, it is astringent and styptic: he moreover recommended a fixed alkali made from vine twigs cut in the beginning of March, for the cure of gout and gravel. ”

“ Why the Acid Neutralises the Alkali
"If you question, my son! how is it that the application of the pungent acid of kānjika relieves the burning of the fire-like hot alkaline caustic, then hear the following explanation from me. Alkalies possess all the tastes except that of the acid. The acrid taste prevails in it and the saline one to a less degree (cf. ante p. 28) . The sharp saline taste when mixed with acid becomes very mild, and gives up its sharp quality. From this modification of the saline taste, the pain of caustics is relieved just as fire is extinguished by water." ”

“ If an alkaline solution mixed with an acid destroys its sourness, and prevents it from reddening vegetable blues, it is because the specific effect of the alkali is to combine with the acid, and form a compound with totally different qualities. ”

“ When we consider that the attraction of alkalis for fixed air is weaker than that of the calcarious earths, and reflect upon the effects of heat in chemistry, we are led to imagine, that alkalis might be entirely deprived of their air, or rendered perfectly caustic, by a fire somewhat weaker than that which is sufficient to produce the same change upon lime ”

“ The volatile alkali and magnesia are placed in the same line of this column; because their force of attraction seems pretty equal. When we commit a mixture of magnesia and salt ammoniac to distillation, the alkali arises and leaves the acid with the magnesia; because this earth, by attracting the acid, represses its volatility, and it seems also to diminish the cohesion of the acid and alkali, and to render them separable by a gentle heat. ”

“ This Acid effervesces with fixed and volatile Alkalis, and therewith forms Neutral Salts; but very different from Sea-salt, and from Sal Ammoniac. That which has a fixed Alkali for its basis does not crackle when thrown on burning coals; but swells and vitrifies like Borax. That which has a volatile Alkali for its basis shoots into long pointed crystals; and, being urged by fire in a retort, lets go its volatile alkali, [Pg 210] a vitrified matter remaining behind. This Salt is like that above-mentioned, as obtained from urine and yielding Phosphorus. ”

“ Volatile Alkalis act upon several metallic substances, and particularly on copper; of which they make a most beautiful blue solution. On this property depends a pretty singular effect, which happens sometimes when we attempt, by means of a Volatile Alkali, to separate copper from any acid with which it is combined. Instead of seeing the liquor grow turbid, and the metal fall, both which generally happen when any Alkali whatever is mixed with a metallic solution, we are surprised to observe the solution of copper, upon adding a Volatile Alkali, retain its limpidity, and let fall no precipitate ”

“ As the weight of bleaching-powder consumed in the world is at most one-fifth of that of alkali, calculated as Na2CO3, it follows that only about one-tenth of all the alkali required could be made by electrolysis, even supposing the Leblanc process to be entirely abolished. The remaining nine-tenths of alkali must be supplied from other sources, chiefly the ammonia-soda process. As long as the operation of the Leblanc process is continued, it will supply a certain share of both kinds of products. ”