Mr. J. Salleron has devised several apparatus which are destined to render valuable service in the champagne industry. The apparently simple operation of confining the carbonic acid due to fermentation in a bottle in order to blow the cork from the latter with force at a given moment is not always successful, notwithstanding the skill and experience of the manipulator. How could it be otherwise?
Everything connected with the production of champagne wine was but recently unknown and unexplained. The proportioning of the sugar accurately dates, as it were, from but yesterday, and the measurement of the absorbing power of wine for carbonic acid has but just entered into practice, thanks to Mr. Salleron's absorptiometer. The real strength of the bottles, and the laws of the elasticity of glass and its variation with the temperature, are but little known. Finally, the physical constitution of cork, its chemical composition, its resistance to compression and the dissolving action of the wine, must be taken into consideration. In fact, all the elements of the difficult problem of the manufacture of sparkling wine show that there is an urgent necessity of introducing scientific methods into this industry, as without them work can now no longer be done.
No one has had a better opportunity to show how easy it is to convert the juice of the grape into sparkling wine through a series of simple operations whose details are known and accurately determined, so we believe it our duty to recommend those of our readers who are particularly interested in this subject to read Mr. Salleron's book on sparkling wine. We shall confine ourselves in this article to a description of two of the apparatus invented by the author for testing the resistance of bottles and cork stoppers.
It is well, in the first place, to say that one of the important elements in the treatment of sparkling wine is the normal pressure that it is to produce in the bottles. After judicious deductions and numerous experiments, Mr. Salleron has adopted for the normal pressure of highly sparkling wines five atmospheres at the temperature of the cellar, which does not exceed 10 degrees. But, in a defective cellar, the bottles may be exposed to frost in winter and to a temperature of 25° in summer, corresponding to a tension of ten atmospheres. It may naturally be asked whether bottles will withstand such an ordeal. Mr. Salleron has determined their resistance through the process by which we estimate that of building materials, viz., by measuring the limit of their elasticity, or, in other words, the pressure under which they take on a new permanent volume. In fact, glass must be assimilated to a perfectly elastic body; and bottles expand under the internal pressure that they support. If their resistance is insufficient, they continue to increase in measure as the pressure is further prolonged, and at every increase in permanent capacity, their resistance diminishes.
Fig. 1. - MACHINE FOR TESTING BOTTLES.
The apparatus shown in Fig. 1 is called an elasticimeter, and permits of a preliminary testing of bottles. The bottle to be tested is put into the receptacle, A B, which is kept full of water, and when it has become full, its neck is played between the jaws of the clamp, p. Upon turning the hand wheel, L, the bottle and the receptacle that holds it are lifted, and the mouth of the bottle presses against a rubber disk fixed under the support, C D. The pressure of the neck of the bottle against this disk is such that the closing is absolutely hermetical. The support, C D, contains an aperture which allows the interior of the bottle to communicate with a glass tube, a b, which thus forms a prolongation of the neck of the bottle. This tube is very narrow and is divided into fiftieths of a cubic centimeter. A microscope, m, fixed in front of the tube, magnifies the divisions, and allows the position of the level of the water to be ascertained to within about a millionth of a cubic centimeter.
A force and suction pump, P, sucks in air through the tube, t, and compresses it through the tube, t', in the copper tube, T, which communicates with the glass tube, a b, after passing through the pressure gauge, M. This pump, then, compresses the air in the bottle, and the gauge accurately measures its pressure.
To make a test, after the bottle full of water has been fastened under the support, C D, the cock, s, is opened and the liquid with which the small reservoir, R, has been filled flows through an aperture above the mouth of the bottle and rises in the tube, a b. When its level reaches the division, O, the cock, s, is closed. The bottle and its prolongation, a b, are now exactly full of water without any air bubbles.
The pump is actuated, and, in measure as the pressure rises, the level of the liquid in the tube, a b, is seen to descend. This descent measures the expansion or flexion of the bottle as well as the compression of the water itself. When the pressure is judged to be sufficient, the button, n, is turned, and the air compressed by the pump finding an exit, the needle of the pressure gauge will be seen to redescend and the level of the tube, a b, to rise.
If the glass of the bottle has undergone no permanent deformation, the level will rise exactly to the zero mark, and denote that the bottle has supported the test without any modification of its structure. But if, on the contrary, the level does not return to the zero mark, the limit of the glass's elasticity has been extended, its molecules have taken on a new state of equilibrium, and its resistance has diminished, and, even if it has not broken, it is absolutely certain that it has lost its former resistance and that it presents no particular guarantee of strength.
The vessel, A B, which must be always full of water, is designed to keep the bottle at a constant temperature during the course of the experiment. This is an essential condition, since the bottle thus filled with water constitutes a genuine thermometer, of which a b is the graduated tube. It is therefore necessary to avoid attributing a variation in level due to an expansion of the water produced by a change in temperature, to a deformation of the bottle.
The test, then, that can be made with bottles by means of the elasticimeter consists in compressing them to a pressure of ten atmospheres when filled with water at a temperature of 25°, and in finding out whether, under such a stress, they change their volume permanently. In order that the elasticimeter may not be complicated by a special heating apparatus, it suffices to determine once for all what the pressure is that, at a mean temperature of 15°, acts upon bottles with the same energy as that of ten atmospheres at 25°. Experiment has demonstrated that such stress corresponds to twelve atmospheres in a space in which the temperature remains about 15°.
In addition, the elasticimeter is capable of giving other and no less useful data. It permits of comparing the resistance of bottles and of classifying them according to the degree of such resistance. After numerous experiments, it has been found that first class bottles easily support a pressure of twelve atmospheres without distortion, while in those of an inferior quality the resistance is very variable. The champagne wine industry should therefore use the former exclusively.
Various precautions must be taken in the use of corks. The bottles that lose their wine in consequence of the bad quality of their corks are many in number, and it is not long since that they were the cause of genuine disaster to the champagne trade.
Mr. Salleron has largely contributed to the improving of the quality of corks found in the market. The physical and chemical composition of cork bark is peculiarly favorable to the special use to which it is applied; but the champagne wine industry requires of it an exaggerated degree of resistance, inalterability, and elasticity. A 1¼ inch cork must, under the action of a powerful machine, enter a ¾ inch neck, support the dissolving action of a liquid containing 12 per cent. of alcohol compressed to at least five atmospheres, and, in a few years, shoot out of the bottle and assume its pristine form and color. Out of a hundred corks of good quality, not more than ten support such a test.
In order to explain wherein resides the quality of cork, it is necessary to refer to a chemical analysis of it. In cork bark there is 70 per cent. of suberine, which is soluble in alcohol and ether, and is plastic, ductile, and malleable under the action of humid heat. Mixed with suberine, cerine and resin give cork its insolubility and inalterability. These substances are soluble in alcohol and ether, but insoluble in water.
According to the origin of cork, the wax and resin exist in it in very variable proportion. The more resinous kinds resist the dissolving action of wine better than those that are but slightly resinous. The latter soon become corroded and spoiled by wine. An attempt has often been made, but without success, to improve poor corks by impregnating them with the resinous principle that they lack.
Various other processes have been tried without success, and so it finally became necessary simply to separate the good from the bad corks by a practical and rapid operation. A simple examination does not suffice. Mr. Bouché has found that corks immersed in water finally became covered with brown spots, and, by analogy, in order to test corks, he immersed them in water for a fortnight or a month. All those that came out spotted were rejected. Under the prolonged action of moisture, the suberine becomes soft, and, if it is not resinous enough, the cells of the external layer of the cork burst, the water enters, and the cork becomes spotted.
It was left to Mr. Salleron to render the method of testing practical. He compresses the cork in a very strong reservoir filled with water under a pressure of from four to five atmospheres. By this means, the but slightly resinous cork is quickly dissolved, so that, after a few hours' immersion, the bad corks come out spotted and channeled as if they had been in the neck of a bottle for six months. On the contrary, good corks resist the operation, and come out of the reservoir as white and firm as they were when they were put into it.
Fig. 2. - SALLERON'S APPARATUS FOR TESTING CORKS.
Fig. 2 gives a perspective view of Mr. Salleron's apparatus for testing corks. A reservoir, A B, of tinned copper, capable of holding 100 corks, is provided with a cover firmly held in place by a clamp. Into the cover is screwed a pressure gauge, M, which measures the internal pressure of the apparatus.
A pump, P, sucks water from a vessel through the tubulure, t', and forces it through the tubulure, t, into the reservoir full of corks. After being submitted to a pressure of five atmospheres in this apparatus for a few hours, the corks are verified and then sorted out. In addition to the apparatus here illustrated, there is one of larger dimensions for industrial applications. This differs from the other only in the arrangement of its details, and will hold as many as 10,000 corks. - Revue Industrielle.