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FARMERS' REGISTER. 



[No. 3 



steeps employed by distillers and brewers; it 

 goes in general terms by the name of lermenta- 

 tion. When the vegetable matter abounds in 

 starch, the first change is the conversion of this 

 principle into sugar. Sugar, if thus lormed, is 

 next converted into alcohol; as it is, if it previous- 

 ly existed in the plant. The presence ol' alcohol^ 

 gives the liquid in which it exists the character of 

 vinous liquors, and if these are permitted to re- 

 main in a turbid state, a farther fermentation con- 

 verts them into vinegar; and finally vinegar is 

 farther decomposed, and the vegetable matter, 

 giving out an offensive smell, is said to putrefy. 

 If the substance be not an expressed juice, or liquid 

 steep, these several stages of fermentation ensue 

 with rapidity, may be going on at the same time, 

 and are sometimes so speedy in their course, that 

 no other action but the putrefactive fermentation 

 can be detected. Animal bodies are subject to the 

 same laws, and go through the same stages of 

 fermentation, but the rapidity which they run into 

 putrefaction is even greater; still there are some 

 cases, as in that of milk, where the vinous stage 

 can be occasionally, and the acetic distmctly, ob- 

 served. Thus, a vinous liquor is prepared in some 

 countries from milk, and the sour taste which ap-^ 

 pears in it when kept, arises from the presence of 

 vinegar. 



In the several stages of fermentation, parts of 

 the vegetable assume the form of gas or vapor, 

 and are given out to the air. The gases which 

 have been detected, are carbonic acid, a gaseous 

 compound of carbon and hydrogen, and in some 

 instances ammonia. The vapor is that of water, 

 which escapes in greater quantities than it would 

 under ordinary circumstances, in consequence of 

 the heat with which the process is attended. If 

 exposed to rain, soluble salts, with earthy and al- 

 kaline bases, are washed from the mass. Finally, 

 a mass of earthy consistence alone remains, which 

 on examination is found to be made up of earths, 

 insoluble salts, and carbon, being, in fact, identical 

 with vegetable mould. 



We may hence infer that the following elements 

 exist in vegetable bodies: 



1. Oxygen, developed in the carbonic acid and 

 water. 



2. Hydrogen is in the water and carburets of 

 hydrogen. 



3. Carbon. 



4. Earths. 

 6. Alkalis. 



6. Nitrogen, occasionally developed in the form 

 of ammonia. 



7. Acids, remaining in the insoluble, or washed 

 away in the soluble salts. 



The chemical examination of vegetable bodies 

 ought of course to lead to similar results. This ex- 

 amination has been conducted in three different 

 ways. 



1. With the view of discovering the nature of 

 the compounds, called vegetable principles, 

 which exist ready formed in plants. 



2. For the purpose of discovering the chemical 

 elements contained in these princi|)les. 



3. By the destructive action of heat, under 

 which some of the elements are wholly sep- 

 arated, and others enter into new combina- 

 tions. 



In the first of these methods there have been 

 detected: 



I. Certain peculiar acids, of which Ave may 

 cite 



(1) Acetic acid, which, mixed with water, 



forms common vinegar; 



(2) Citric acid, which is found in the lemon 



and orange; 



(3) Malic acid,"\vhich exists in the apple; 



(4) Tartaric acid, in the juice of the grape; 



(5) Oxalic acid in the wild sorrel. 



II. Certain substances of alkaline character, 



found principally in medicinal plants, to 

 which they give their peculiar virtues. 



III. Gum, resin, oils, sugar, starch, and two sub- 



stances approaching to animal matter in 

 their characters, namely, albumen and 

 gluten; the former of these has a resem- 

 blance to the white of eggs, the latter to 

 animal jelly or glue. 

 Many other principles are separated by the same 

 method in difierent plants, but need not be enume- 

 rated by us. 



The basis of this method consists in acting upon 

 vegetables by water, ether, or rectified spirits (al- 

 cohol,) and the principles above enumerated are 

 either simply, or in the state of combination in 

 which they exist in plants, soluble in at least one 

 of the liquids we have named. 



In all cases some insoluble matter is left, and 

 this is known by the name, of the woody fibre. 



When these principles are treated by the second 

 method, oxygen, hydrotren, and carbon, are the 

 uniform results, but in different proportions in the 

 dilierent cases; nitrogen is also detected in someoT 

 them, as, lor instance, in the alkaline principles, 

 and in gluten. T4iis method does not appear to 

 be adequate to determine whether earths and al- 

 kalis are, or are not, parts of these vegetable prin- 

 ciples. From the very remarkable fact, that some 

 of those substances, which are very dissimilar to 

 each other, yield exactly the same proportions of 

 oxygen, hydrogen, and carbon, we may fairly con- 

 clude by chemical analogy, that one or the other, 

 or perhaps both, contain some substances which 

 have escaped the analysis. As an instance, we 

 may cite starch and sugar, whose characters are 

 so dissimilar that no danger can exist of mistaking 

 the one for the other; and yet their analysis by the 

 second method gives identical results. 



The third method may be understood by conrr- 

 paring it with the process used in making charcoaT. 

 If this be so far altered that the heat employed 

 shall not arise li'om the combustion of a part of the 

 substance to be examined, but from one merely 

 used as fuel, and if the matters which escape in 

 smoke are condensed and collected, we shall have 

 that employed occasionally on a large scale by 

 operative chemists. In this way, coarcoal will be, 

 as usual, obtained in the solid form. The fconden- 

 sible products will be water, tar, turpentine, or re- 

 sin; and the acid which gives that character to 

 vinegar, but which, in the present case, in union 

 with the tar and water, is calletl pyrolignous 

 acid. 



If the charcoal be burnt in a current of air, all 

 its carbon is converted, by union with the oxygen 

 of the atmosphere, into carbonic acid, leaving a 

 residue fiimiliarly known as ashes. The ashes 

 are made u|) partly of soluble and partly of insol- 

 uble matter. The soluble matter is separated by 

 the familiar process of making lej^, and the ley, if 

 evaporated, leaves the Bolid eubetance bo well 

 known as potash. 



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