Page:Popular Science Monthly Volume 5.djvu/570

552 of heat, so as to destroy the yeast-germs. There was no possibility of doubt as to the destruction of these germs and the prevention of any further change, but it might well be asked whether the delicacy and bouquet of certain wines would not be endangered by the effects of heating. Long-continued experiments prove not only that heating is an excellent method for preventing sickness in wines, but also that, instead of impairing their exquisite qualities, it ripens and strengthens them. The recorded minutes of tastings officially performed during the past year by several members of the syndical wine commission, at the suggestion of M. Pasteur, contain decisive testimony on this point. Fine Burgundy wines, heated in bottle seven years ago to temperatures varying between 131° and 149°, appeared, at the end of that time, superior to the same wines not so treated. Persons who spoke with some authority, M. Pasteur says, declared that heating would in time deprive the wine of its color. The contrary is the case, when the air is excluded during the process; the color grows livelier by heating. It was said that heating would in time alter the bouquet of fine wines, giving them dryness and too great age. On the contrary, the bouquet seems to be heightened with the lapse of time, more positively than with wines not heated. In the case of chambertin and volnay particularly, the tasters noticed this fact. M. Pasteur was led by these studies to investigate the cause of the aging of wines, and he discovered that the phenomenon was due to slow oxidation. Wine kept in glass tubes completely filled and closely sealed does not age. By increasing and regulating the aeration of wine, and particularly combining it with heating, he succeeded in manufacturing in one month excellent old wine. In short, oxygen and heat, acting on wine in certain proportions, promote instead of hindering the development of those volatile principles to which the liquid owes its perfume and part of its flavor; but this discovery is additional to those sought. What M. Pasteur did chiefly look for and did find, in giving exact and methodical rules for heating wines, is a process, applicable on a great scale, for preventing the diseases from which the common vineyard products so often suffer, and that fortunate application is a result from his researches on fermentation generally. In the same way, in consequence of the examinations he undertook as to the share of microscopic organisms in the diseases of silk-worms, he was led to prescribe a practical way of hindering the development of these organisms, and thus preventing the malady.

When we inject into the subcutaneous cellular tissue of a living animal a putrefied or septic liquid, that is, one containing those threadlike corpuscles known by the name of vibrios and bacteria, it sometimes happens that the animal experiences no inconvenience. Dogs particularly resist with vigor the poisonous influence of such a fluid, but the case is different with other species, and notably with rabbits. The system becomes the seat of grave phenomena, almost always