The mineral acids—alcohol, camphor and most metallic salts—do not pass into the urine to any sensible degree. _Urine in Diabetes._—The most remarkable change in the nature of urine occurs in Diabetes Mellitus, it is voided in great quantity; it is found to contain a great quantity of grape, sugar, and very little urea. It was supposed that in this disease urea ceased to be formed by the system, and was replaced by sugar; but it has been shown that, although the quantity of urea is very small in any one specimen of urine, yet the total quantity is so much increased that in twenty-four hours the natural quantity of urea is secreted; the secretion of sugar being an act of faulty digestion, and totally unconnected with the urea. These results have been fully confirmed by experience. The diabetic urine sometimes contains albumen, which arises from complications of other forms of disease. All that has been said in the former chapter about the solid and fluid constituents of the human body may, at first sight, and to a great many, seem to be superfluous and out of place in a work of this kind. It is true that the different modes of preserving bodies, as explained in this book, do not require this long dissertation on animal chemistry in order to be understood; still, when we consider that the chemicals used in these different processes have an object to accomplish, it must be granted that a thorough knowledge of the constituents of the body, their composition and chemical proportion, will, to a great extent, explain the reason why these same chemicals are used in preference to others. The secondary object, which is not less important, consists in the fact that a thorough knowledge of the animal chemistry of the human organism is most necessary to understand the different changes which take place in the formation of the different juices and tissues of the body, when they enter into combination with the chemicals, the object of which is to render them imputrescible. However, the study of these combinations affords a simple and clear explanation of the means resorted to in order to preserve bodies. GANNAL’S PROCESS OF EMBALMING. WITH MODIFICATIONS. This process, which has been successfully employed in Europe for a long time, for the purpose of embalming bodies and for the preservation of anatomical preparations, is still practised extensively, owing to the cheapness of the materials used and to the simplicity of the modus operandi. The embalming fluid in this instance is composed as follows, viz.: Sulphate of alumina, 4 pounds. Arsenious acid, 4 ounces. Creasote, 4 ounces. Water, 1 gallon. To prepare this fluid, an explanation of its constituents is required.