DIAGNOSIS, INCLUDING THE TESTS FOR SUGAR IN THE URINE.--The diagnosis of diabetes mellitus, the disease being once suspected, is easy. The passage of large amounts of pale urine of high specific gravity, the presence of thirst, dryness of the mouth, fauces, and skin, and progressive emaciation even while the appetite is good, can scarcely be misinterpreted. In the urine from such a case the application of any of the tests for sugar will produce prompt response. The urine is not always so much increased as to attract attention, while its color is also sometimes but slightly changed; but the symptoms of thirst and dryness or clamminess of the mouth are seldom wanting. On the other hand, the discovery of a glycosuria without these symptoms is, as a rule, accidental. It is a question how far such degrees of glycosuria as do not produce the usual symptoms of diabetes in an appreciable degree are signs of positive disease. At the same time, its detection is important, in that there is always danger of the simple glycosuria becoming a diabetes--a danger which its recognition and suitable treatment may avert. Accordingly, the urine of all persons having unusual appetites without evident cause, {211} and of those who are fond of eating and drinking, should be tested for sugar. This should also be done for those who have passed through severe mental or physical strain, have suffered shock or concussion of the nervous system, blows upon the abdomen, etc. Testing for Sugar.--Under the head of Diagnosis I prefer to include the testing for sugar, which requires some detailed consideration. Unless it be that the indigo test recently revived by George Oliver of London prove more delicate, that form of cupric test known as Fehling's solution is, with suitable precautions, all things considered, the most satisfactory for general use. Fehling's volumetric solution, suitable for both qualitative and quantitative purposes, is made as follows: Dissolve 34.639 grams of pure crystallized cupric sulphate in about 200 cubic centimeters of distilled water; 173 grams of chemically pure crystallized neutral sodio-potassic tartrate and 80 grams of potassium hydrate in 500 or 600 c.c. of distilled water. To the latter add the copper solution slowly, and dilute the clear mixed fluid to 1 liter. One cubic centimeter of this solution will be decolorized by 0.005 grm. of sugar, or 200 grains will be decolorized by 1 grain of sugar. Or the copper may be dissolved in 1 liter of water, and the tartrate and potassium hydrate in another, and a cubic centimeter of each mixed at the moment they are to be used.