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Part I--General Discussion of Mineral Waters, continued
Chapter IX--Artificial Mineral Waters and Carbonated Beverages
Although attempts were made very early to imitate natural mineral waters, but little progress was made until after the discovery of carbon dioxid by Doctor Black in 1757 and its analysis by the French chemist, Lavoisier. It was, however, to Priestley, the English chemist, that we must give the credit of first proposing, in 1772, to impregnate ordinary water with carbon-dioxid gas, and in accordance with this suggestion prescriptions were published in 1774 for the artificial production of Seltzers and other carbonated waters. From Liebig's analysis of the Friedricksaller an artificial water was easily prepared.
Prof. Torbern Olof Bergman, a Swedish chemist, did much to introduce the use of artificial mineral water. As he had been greatly benefited by the use of mineral waters obtained from Germany, and as at some times of the year it was difficult to obtain them, he analyzed the waters and compounded artificial imitations with great success. He saturated water with carbonic "aerial" acid gas, and added to this the required quantity of mineral salts. He probably used the "agitator" devised by the French Duke de Chaulnes in the process of carbonating.
The Seltzer waters were made in 1787 on a large scale by Meyer, at Stettin, Germany. Paul erected a factory for the same purpose in Paris in 1799. In Great Britain a patent for impregnating water with carbon-dioxid gas was taken out in 1807, and a similar patent was taken out in Charleston, S. C., in 1810. Doctor Struve, in 1815, in the city of Dresden, began the manufacture of artificial mineral waters, exactly imitating those found in nature, and the same physician introduced these waters into medical use. More recently this business has been greatly extended all over the world, and at present imitations of all the famous natural mineral waters are prepared in the laboratory. Indeed, after a study of the composition of a particular water, the bottler prepares a similar beverage, which is not identical, however, because certain substances, considered of no use, are left out in compounding.
By the use of carbon dioxid it is possible to hold in solution mineral substances which would otherwise be precipitated as soon as the water is exposed to the air. This is especially true of the compounds of manganese, iron, calcium, and magnesium. It is probable that the carbonic-acid gas is of service also in displacing the air, and so preventing oxidation and sometimes deterioration of the waters.
The manufacturer of the artificial mineral water uses, as far as possible, ingredients which will, when added to water and carbonated, give constituents similar to those in the natural water. These chemical salts must be of such a character that they will not be incompatible or precipitate each other. The recently precipitated hydroxids or carbonates are much more soluble than the ordinary dry salts, and, in the process of compounding, groups of substances in solution are added in a definite order. Some substances, such as citric acid or sodium pyrophosphate, are often added as "preservatives" of these artificial waters, the object being especially to keep iron in solution.
The Manufacture of Carbon-Dioxid Gas
Since the time of Priestley, who, in 1772, made an apparatus for the production of "fixed air," as he called it, from a mixture of chalk and "oil of vitriol," to the present time, a great deal of ingenuity has been expended on apparatus for this purpose (A Treatise on Beverages, or the Complete Practical Bottler, Chas. H. Sulz). Historically considered, the following types of apparatus have been introduced:
The Geneva or Semi-continuous System
This is the old form of generator used in Europe. The gas was generated in a wooden cylinder, passed into a gasometer or storage tank, then by means of a force-pump into a strong cylinder containing water and provided with an agitator. By this plan, after one "batch" of gas was used the apparatus had to be cleaned out.
The Continuous System
In this "direct-action" process, as it is called, the gas is generated in a leaden vessel, just enough acid being brought in contact with the carbonate, usually mixed with water, to generate the gas. Then the gas is washed through water and allowed to expand in a "gasometer." The "soda-water machine" proper consists of a force-pump, which pumps, at the same time, water and gas into a strong cylinder, provided with an agitator to assist in the solution of the gas in the water.
The Intermittent System
By this plan the gas is dissolved in water by the pressure produced in the generator from the chemical action of the acid on the carbonate, without the aid of a pump or gasometer. Of course, the greater the pressure the more gas the water will dissolve. In order to make the apparatus continuous, it is only necessary to have several generators, two at least, so that the material in one apparatus may be renewed while the other is in use. There are often pumps attached to the apparatus as used in the United States, for filling the cylinders with water. The generators may be so arranged as to be horizontal and acid-feeding, or vertical and carbonate-feeding.
The Liquid Carbonic-acid System
This is the most recent, and bids fair to supplant all the other systems in localities easily reached by transportation. The liquefied gas, made by one of the processes mentioned below, is pumped into strong wrought-iron cylinders about four feet long by five inches in diameter. These cylinders are tested to stand four times the pressure that they ordinarily bear, and hold about twenty pounds of the liquified gas. This represents about 1100 gallons of gas at ordinary atmospheric pressure, and will charge from 200 to 300 gallons of water, according to the pressure desired. As this gas can be purchased at twelve cents or less per pound, it it is evident that, considering the convenience to the manufacturer and dealer, and because it makes it unnecessary to run a somewhat cumbersome machine, the liquefied gas will be extensively used. Even large wholesale bottlers buy the gas in preference to making it.
Materials used in the Manufacture of Carbon-Dioxid Gas
In order to make this gas, a carbonate--as sodium carbonate (Na2CO3), sodium bicarbonate (NaHCO3), or marble dust (CaCO3)--is used, together with an acid, as sulfuric (H2SO4), or hydrochloric (HCl). The cheapest carbonate and the cheapest acid would be selected, other things being equal. The chemist represents the reaction by CaCO3 + H2SO4 = CaSO4 + H2O + CO2. Water and calcium sulfate are left in the generator after the chemical action is over. The carbon-dioxid gas might also be made by the simple combustion of charcoal or coke, but this gas is not very readily purified. Another method of making is by simply heating limestone; thus, CaCO3 + heat=CaO+CO2. The calcium oxid left can be utilized as quicklime.
Another and recent source of the gas is from the vats in which beer is fermenting. By the process of malting some of the starch of the grain is changed into a kind of sugar and this ferments readily with yeast, the products being alcohol and carbon-dioxid gas. The carbon-dioxid gas is pumped off and condensed to a liquid by pressure. The gas obtained in this way must be thoroughly washed and purified before being used. In fact, a process of washing is necessary to purify the gas in whatever way it is made. Sometimes washing with simple water is sufficient, and in other cases more thorough washing through chemical solutions is necessary. This gas finds many uses in the arts. In England it is used instead of yeast in the manufacture of "aerated bread."
Properties of Carbon Dioxid
This gas is much heavier than air, will extinguish a fire, and is not poisonous. As stated above, it may be condensed to a liquid, and when some of this liquid is allowed to escape into the air it vaporizes so rapidly that it takes heat from the surrounding gas and converts it into a snow-white solid. This solid is so cold that it will freeze mercury readily, if brought into contact with it. As noticed above, the carbon-dioxid gas is very soluble in water, and, as the pressure is increased, the colder the water the more is dissolved.
Methods of Using the Liquefied Carbon-Dioxid Gas
There are numerous "carbonators" on the market for use with the liquified gas. The principle on which they work is as follows: The cylinder containing the liquified gas is attached to a pressure gauge and to the carbonator by means of heavy block-tin pipes. The gas is led into an agitator, where it passes through the water, and then into a cylinder, where it is sprayed with the incoming water. It is important that all air in the apparatus be allowed to escape. A pump is used to run the agitator and at the same time to pump water into the mixing cylinder. By means of an automatic arrangement the pump is stopped whenever the water rises to a fixed height in the mixer, and starts again when the liquid has been drawn off below a certain level. The pressure of the charged water can be regulated at will, so that the machine thus furnishes a continuous supply of carbonated water.
As the liquefied gas cools the cylinders rapidly when it escapes, so, in order to prevent a stoppage of the valves by freezing, some manufacturers pass the gas through a steam-jacketed tube to warm it, while others attach several "drums" to one carbonator at the same time, so that the gas shall not expand so rapidly in anyone of them as to cause inconvenience.
The liquefied gas is also used in small steel capsules, known as "sparklets," for carbonating mineral water and other beverages. The capsules are closed with a thin steel cap which, when placed in position in a syphon apparatus, may be punctured by a steel needle, allowing the gas to come in contact with the water.
This gas is of great use in the carbonating of natural mineral waters, so as to keep in solution mineral substances that would otherwise separate out when standing, and also to improve the taste of a water by the additional flavor and effervescence of the gas.
Carbonated and Saccharine Beverages
The manufacture of soda-water, pop, ginger ale, sarsaparilla. and such beverages is so closely related to that of artificial mineral water that it should be discussed in this connection.
It is important that the water used be of good quality, but there is reason to believe that some manufacturers are careless in this respect. The effect of great pressure, lack of oxygen and the presence of carbon dioxid in the water, on the microbes that might exist there, has received considerable study. Doctor Leone, who examined the water-supply of Munich, showed by a series of experiments that, in a sample of carbonated water, the number of microbes diminished in fifteen days from 186 to 20. He further showed that this decrease in numbers was not due to deficiency of oxygen, nor to great pressure, but to the presence of carbon dioxid in the water. This would seem to indicate, then, that in the use of ordinary carbonated beverages the consumer is, to some extent, protected from the micro-organisms which are present in impure water.
In addition to the water and the carbon dioxid-gas, the bottler uses some or all of the following substances, each of which should be of good quality and standard strength:
- Sweetening material: Cane sugar, if used for this purpose, should be, pure, and free from "bluing" or glucose. Glucose or grape sugar is often used. This has only about three-fourths the sweetening power of cane sugar. It is made by the action of sulfuric acid on starch and the subsequent neutralizing of the solution with marble dust. Competent chemists and physicians have pronounced it, if carefully made, a wholesome sweetening material, but it renders the beverages very liable to fermentation. Honey may be used for sweetening, but, on account of its market value, it is very liable to adulteration. Saccharin (C6H4CO SO2 NH), which is not a sugar at all but a sweet substance made in the laboratory from coal-tar, is a remarkable product which is coming into very extensive use. Cane sugar can scarcely be detected by the sense of taste in a solution that contains 1 part in 250 parts of water, but saccharin can be detected in a solution containing but 1 part in 70,000 parts of water. It is not usually considered injurious to the human system, though there are some who hold an opposite opinion. It is something of an antiseptic, and does not ferment like sugars.
- Fruit syrups made from genuine fruits are used. These may be made from fermented or unfermented juices, and are sometimes "animated" by the addition of a little artificial fruit essence.
- Compound syrups have the most extended use and are made from a great variety of organic ethers and other substances.
- In many of these preparations coloring matters, made from organic dyestuffs or aniline colors, are employed.
- Essential oils and extracts of vegetable origin in great variety are used for flavoring.
The manufacturer of these beverages, in bottling, simply allows a measured quantity of the flavored and prepared syrup to flow, by means of a block tin pipe, into the bottle placed in the bottling-machine, and it is then immediately filled with the carbonated water, under pressure of perhaps eighty pounds to the square inch, and is closely corked.
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Kansas Geological Survey, Geology
Placed on web April 7, 2017; originally published 1902.
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