The "stinking fermentations" occasionally experienced in breweries probably arise from this, the free sulphur being derived from the hops.
Certain acid fermentations are of common occurrence.
His publications include Chimie appliquee a la physiologie et a la pathologie animate (1863); Traite des matieres colorantes (1867); Les Fermentations (1875), which was translated into German, Italian and English; and an excellent Traite de chimie generate in seven volumes (1880-1894).
The fact is that the constitution of average grape juice and the temperatures of fermentation which generally prevail are particularly well suited to the life action of wine yeast, and are inimical to the development of the other organisms. When these conditions fail, as is, for instance, the case when the must is lacking in acidity, or when the weather during the fermentation period is very hot and means are not at hand to cool the must, bacterial side fermentations may, and do, often take place.
These wines, therefore, require very careful handling in order to prevent undesirable secondary fermentations taking place at a later period.
Apart from numerous fermentation processes such as rotting, the soaking of skins for tanning, the preparation of indigo and of tobacco, hay, ensilage, &c., in all of which bacterial fermentations are concerned, attention may be especially directed to the following evidence of the supreme importance of Schizomycetes in agriculture and daily life.
As able to carry on one particular series of fermentations or decompositions only, and since they require no organic food materials, or at least are able to work up nitrogen or carbon from inorganic sources, he regards them as primitive forms in this respect and terms them Prototrophic. They may be looked upon as the nearest existing representatives of the primary forms of life which first obtained the power of working up non-living into living materials, and as playing a correspondingly important role in the evolution of life on our globe.
W.) No milk is free from bacteria, because the external orifices of the milk-ducts always contain them, but the forms present in the normal fluid are principally those which induce such changes as the souring or " turning " so frequently observed in standing milk (these were examined by Lord Lister as long ago as 1873-1877, though several other species are now known), and those which bring about the various changes and fermentations in butter and cheese made from it.
Promise of more light on these oxidation fermentations is afforded by the recent discovery that not only bacteria and fungi, but even the living cells of higher plants, contain peculiar enzymes which possess the remarkable property of " carrying " oxygen - much as it is carried in the sulphuric acid chamber - and which have therefore been termed oxydases.
Even when the light is not sufficiently intense, or the exposure is too short to kill the spores, the experiments show that attenuation of virulence, That bacterial fermentations are accompanied by the evolution of heat is an old experience; but the discovery that the " spontaneous " combustion of sterilized cotton-waste does not occur simply if moist and freely exposed to oxygen, philous bacteria.
These facts, and the further knowledge that many bacteria never observed as parasites, or as pathogenic forms, produce toxins or poisons as the result of their decompositions and fermentations of organic substances, have led to important results in the applications of bacteriology to medicine.
It is very probable that numerous symbiotic fermentations in the soil are due to this co-operation of oxygen-protecting species with anaerobic ones, e.g.
Fermentations induced by them, the resistance of their spores to dessication, heat, &c. - but it is worth while to ask how far these properties are really remarkable when all the data for comparison with other organisms are considered.