66 



NEW ENGLAND FARMER. 



Feb. 



of the four kinds above named. The process 

 of fermentation is somewhat varied, according 

 to tlie substances upon which it acts, and the 

 circumstances under which it is carried on. 

 It may be more readily excited, and carried 

 on more vigorously, by the addition of some 

 fermf-nt. When fermentation is set up artifi- 

 cially, the ferment most commonly used is 

 called yeast, — a substance prepared from the 

 altered gluten of barley in the process of 

 brewing. Any albuminous substance in a 

 state of decay, as flesh, fish, glue, cheese, &c. 

 will produce the same result in time, but the 

 yeast from malted barley seems to possess this 

 power in the highest degree, and acts more 

 rapidly than any other substance. Yeast is 

 produced from the gluten of barley acted up- 

 on by a substance developed in the process of 

 malting, called diastase, whose nature and 

 mode of action do not seem to be well under- 

 stood. If this substance or a mixture contain- 

 ing it, be added to a mixture of starch and 

 ■water, or of vegetable substances containing 

 starch, the starch will lie changed into gum or 

 dextrine, and this will be changed into sugar. 

 This is the first kind of fermentation, or as it 

 is called, the saccharine or sugar-making fer- 

 • mentation. Now if this process is allowed to 

 go on, or if to a solution of honey or grape 

 sugar in water, yeast be added, the sugar will 

 part with a portion of its carbon and oxygen 

 and be converted into alcohol. The portions 

 of carbon and oxygen which the sugar has lost 

 will combine and form carbonic acid, and thus 

 the products of this kind or stage of fermen- 

 tation will be alcohol and carbonic acid. This 

 is the fermentation which takes place in the 

 working of wine, cider and beer, all of which 

 liquids contain sugar and albuminous matter. 

 The intestine motion that goes on in the liquids 

 during the process, is owing to the formation 

 of carbonic acid which rises to the surface. 

 This process goes on until all the sugar pres- 

 ent is converted into alcohol, provided there 

 is also present sufiicient albummous matter or 

 ferment. If there is not, a portion of the su- 

 gar remains unchanged, giving to the resulting 

 Bquid a sweet taste. It is in this way that 

 sweet wines are prepared, — a portion of the 

 sugar contained in the grape juice remaining 

 unchanged, ^\'hen the process of fermenta- 

 tion in cider is arrested by the addition of any 

 substance having the power of arresting it, a 

 portion of the sugar remains unchanged, and 

 the cider is thereby rendered sweet. 



The vinous fermentation, or the conversion 

 of sugar into alcohol, may be arrested by the 

 essential oils that contain sulphur, — as the oil 

 of mustard and horseradish, or by the action 

 of sulphurous acid, which has the power of 

 rendering the yeast inactive. Sulphuric acid 

 also possesses the same power, which is more 

 especially shown in rendering inactive the fer- 

 menting matter in putrefactive fermentation. 

 Hence sulphate of lime, iron and zinc are used 

 in putrefying masses as deodorizers. They 



act by preventing for a time, the evolution of 

 offensive gases. The sulphite of lime, which 

 is a combination of sulphurous acid with lime, 

 has recently been used to arrest vinous fer- 

 mentation. Care should be taken that enough 

 of this substance should not be added to the 

 fermenting liquid to leave the smell or taste of 

 sulphur. 



In the acetous fermentation, the alcohol pre- 

 viously formed from the sugar, is converted 

 into acetic acid or vinegar. The alcohol is 

 oxydized by the oxygen of the atmosphere. 

 Hence it is necessary in this process that there 

 shonld be free access of air. 



If the products of vinous fermentation, as 

 wine, cider or beer be exposed to the air at a 

 temperature over 66° F., and if some ferment 

 be present, and especially if some vinegar be 

 added to it, or some of that slimy substance 

 found at the bottom of vinegar casks, called 

 mother, this form of fermentation will go on 

 till all the alcohol is changed into acetic acid 

 and water. When sugar is present in the al- 

 coholic liquid, the vinous fermentation may go 

 on at the same time with the acetous, and the 

 sugar be changed into alcohol, while the al- 

 cohol is being changed into acid. Acetic acid 

 is a very strong, pungent, corrosive acid. 

 Common vinegar contains but a small per 

 cent, of it, the remainder consisting chiefly of 

 water and coloring matter. The revenue 

 standard in England is five per cent. 



In the putrefactive fermentation of animal 

 and vegetable substances, air and moistuie 

 must be present, and the temperature must be 

 between the freezing and boiling points, as it 

 is wholly arrested by a temperature indicated 

 by either of these points. Any putrid sub- 

 stance will act as a ferment upon fiesh animal 

 or vegetable substances. Hence if straw, 

 peat or other vegetable matters be mixed with 

 putrid animal manures, the process of putre- 

 faction is soon communicated to the whole 

 mass, and an active compost is formed. 



During this fermentation, several gases are 

 formed and given off from the decomposition 

 of the albuminous matter present in the putre- 

 fying mass. These matters contain nitrogen, 

 sulphur and phosphorus, which combine with 

 hydrogen, and form ammonia and sulphureted 

 and phosphoreted hydrogen. These are the 

 offensive gases which have been already al- 

 luded to. The hydrogen is furnished by the 

 decomposition of water, whose o.xygen com- 

 bines with carbon, forming carbonic acid. 



Much has been said and written upon fermen- 

 tation, and that portion of it which relates to 

 ferments and their origin and mode of action 

 is still involved in mystery. Ferments appear 

 to communicate nothing to the fermenting 

 mass, nor to take any thing from them, and 

 yet as we know a "little leaven will leaven 

 the whole lump." Ferments seem to act upon 

 bodies exposed to them much as contagious 

 disease attacks healthy bodies, by a sort of 

 infection which causes an action in the body 



