at home and abroad, as will be seen from what is contained in the present work. By the German translation that was published at Göttingen, in 1864, unknown to the author until after its appearance, a full ventilation of his views has been afforded on the Continent.

35, GROSVENOR STREET,

GROSVENOR SQUARE.

December, 1868,

ON THE DETECTION

AND

QUANTITATIVE DETERMINATION OF SUGAR.*

DIABETES MELLITUS is a disease which calls for the application of chemistry for the purpose of diagnosis. It is true the experienced physician may, from the history, symptoms, and appearance of the patient in a wellmarked case, pretty safely surmise the existence of the disease, but to be enabled to speak in a positive manner an examination of the urine is required. The examination should be directed in the first instance towards ascertaining whether sugar exist or not; and in the next place, in the event of sugar being found, to the determination of its amount. To ascertain simply that sugar is present in the urine is, it must be said, to obtain but very meagre information about a case. What is also wanted before anything definite can be said is a knowledge of the amount of sugar that is being passed, and the effect of treatment can only be with precision watched by a quantitative examination of the urine, conducted from time to time.

* Messrs. Griffin and Sons, of 22, Garrick Street, Covent Garden, supply the apparatus referred to in the following pages upon the subject of analysis.

Of the varieties of sugar that chemists enumerate, glucose or grape sugar is that which the pathologist has to deal with. There are various means by which its presence may be displayed, but only those in common use need be referred to here. Fortunately for the prosecution of physiological and pathological researches bearing upon sugar, it happens that this principle is one of the most easily recognisable of organic bodies. It may be said, indeed, to be susceptible of detection with almost the same facility and certainty as an inorganic substance, and this, when present, even in very minute quantity.

QUALITY OF SWEETNESS.

Sweetness is one of the most striking properties possessed by sugar, but it is not characteristic of it, and our sense of taste, although sometimes appealed to, is not one that it is convenient and agreeable, nor even at all times safe, to employ to supply information in investigations of an analytical kind. Still, by the sweet taste of their urine diabetic patients have before now themselves discovered the nature of their complaint, and the property of sweetness possessed by diabetic urine was recognised and dilated on by medical authorities before anything was known about the present mode of testing for sugar. Dr. Willis, it seems, was the first to point out the character of sweetness belonging to the urine in diabetes. "The subjects of this affection," said Willis, "pass more urine than the whole quantity of fluids taken into the body; they

have besides a constant thirst and a slow kind of hectic fever always on them. It is very far from true,

as some authors affirm, of the drink being again. discharged with little or no alteration, for the urine in all that I have seen (and I believe it will universally be the case) differed, not only from their drink, and from every other fluid in the animal body, but was like as if it had been mixed with honey or with sugar, and had a wonderfully sweet taste."

The property of sweetness is not a character that it is necessary to recommend in our day to be looked for by the medical practitioner in order to discover if sugar be present in the urine; indeed, if the recommendation were made, it is not probable that it would often be carried out. There are several ways now known by which the point may be otherwise determined.

SPECIFIC GRAVITY.

From the specific gravity of the urine a rough conclusion can be drawn as to the existence of diabetes or not, but it should not be relied upon solely. The sp. gr. simply indicates the amount of solid matter that is contained in the urine. Where diabetes mellitus exists sugar is added to the solid matter naturally present, and so the sp. gr. is raised beyond its natural range. Should only a moderate quantity of sugar be present the sp. gr. would not supply much information, because the proportion of solid matter naturally belonging to the urine is subject under different circumstances to considerable variation; but should the sp. gr. be uniformly maintained at a height much beyond its natural limit, and the quantity of urine be at the same time excessive, diabetes may be presumed with pretty fair certainty to exist.

To determine the sp. gr., either weighing or the use of an instrument known as the hydrometer (urinometer this instrument is called, as specially graduated for the examination of urine), or of little bulbs or beads such as are figured at p. 8, may be employed.

Weighing supplies the most precise information, and should be resorted to for taking the sp. gr. of a fluid in all cases where minute accuracy is required. The sp. gr. bottle is used for the purpose. This consists of a thin glass flask (shown in fig. 1), provided with

a perforated glass stopper. Bottles are sold holding, when full, 1000 and 500 grains of distilled water. When filled with a heavier liquid and placed