After some remarks on the present state of animal chemistry, the author commenced by giving a brief account of the recent discoveries of Liebig in regard to the constituents of the “juice of flesh,” or the liquid contained in the substance of the muscles, which is distinguished from the blood by the large proportion of free acid it contains. This remarkable animal fluid has been found, by Liebig, to contain phosphoric and lactic acids in large quantity, inosinic acid in small proportion, and some other acids not yet studied; also, potash in large quantity with a little soda, a considerable proportion of magnesia, and a little lime, chloride of potassium, with a little chloride of sodium, and, besides some compounds of animal origin not yet investigated, the new base Kreatinine, and the very remarkable substance, Kreatine, first discovered by Chevreul, but in vain sought for by Berzelius and other chemists.