carbonic acid gas had traversed the apparatus. At the end of seven, fourteen, and twenty-one days it was found that the meat was still quite good, and the soup prepared from it was in every respect excellent. At the end of the fourth or fifth week the meat thus preserved in the gas was still quite free from all putridity; but the broth prepared from it no longer tasted so well as fresh bouillon. The experiments were not extended over a longer time. Carbonic acid is thus shown to be an excellent means of preserving beef from putridity and of causing it to retain its good taste for several weeks. Mutton does not preserve so well. In eight days it had become putrid; and veal is by no means so well preserved as beef. The comportment of beef in an atmosphere of carbonic acid, to which carbonic oxide has been added, is curious. A number of cylinders were filled in the usual way with such a mixture and opened at the end of two or three weeks; in each case the flesh had the smell and taste of good, pure meat, but it was not of the gray color which meat preserved in carbonic acid gas gradually takes, but appeared in the interior, as well as on the outside, of a bright flesh-red color, and on the surface here and there, there were white round masses of fungoid growth of the size of a 20-pfenning piece, which were removed with the slightest rubbing. The flesh lying just below these was found to have the same bright red color as that already described. Meat which had been for three weeks in such a gas mixture gave a broth which, in good taste and freshness, could hardly be distinguished from freshly-made bouillon; and the boiled meats could not be distinguished either in appearance or taste. The property of carbonic acid to preserve meat suggests a use for the large supplies of this gas evolved from the earth in many localities. And it is as interesting to determine in how far the gas could be of service as an antiseptic during surgical operations. * * * * * REDUCTION OF OXIDIZED IRON BY CARBONIC OXIDE. IT is well known that when the heat is sufficient, carbonic oxide reduces the oxide of iron to metal with the production of carbon dioxide (carbonic acid). On the other hand, at lower temperatures carbon dioxide oxidizes metallic iron, forming carbonic oxide. J. Lowthian Bell's celebrated researches (see SCIENTIFIC AMERICAN, p. 199, March 31, 1883) established the point of equilibrium where in the presence of both monoxide and dioxide the reducing action of the one just counterbalances the oxidizing action of the other.