tionate to the end sought, unless it be that, in a greatly overcrowded profession, which is still in process of being more and more overcrowded, there is some process of evolution at work, through this movement, whereby a permanent differentiation is to be started for future good.

TESTING URINE FOR GLUCOSE

BY FEHLING'S SOLUTION.

The diseased condition which is characterized by the presence of glucose in the urine, in common with most other chronic diseases, is much more easily cured when treated in the earlier stages; and as the proportion of glucose in the urine is a pretty accurate measure of the stage of the disease which produces it, the importance of detecting and roughly measuring small amounts of glucose in urine can hardly be over-estimated.

Glucose, often called simply sugar, or grape sugar, or invert sugar, or dextrose, is often present in very small proportion in normal urine, and is still more frequently present and in much larger proportion in the urine of healthy persons, after over-feeding or unusual feeding, or some peculiar irregularity of diet or digestion, but present only for a short time, and disappearing with the absence of the special cause. But such temporary presence occurring often and persisting longer from time to time, is the probable early history of every confirmed case; and if so, the early recognition of the symptom will lead to an early investigation of the cause, and the prompt adoption of means for its removal.

The best test for glucose in the urine, and the one most widely known, is by the use of Fehling's standard copper test solution. Many other modes of testing have been proposed and used, and some others are doubtless more critically accurate when in the hands of expert analytical chemists, but no other has stood the test of experience so well, nor proved to be so well adapted to ordinary every-day use by those who needed it most, yet who could not be most expert in the critical use of such agents. Neither do the modifications of Fehling's test, when it is put into the form of solid lozenges or pellets, seem to be always trustworty, convenient though they may

be, so that the slightly modified or improved solution of later years seems to be the test best adapted to common use.

It is, however, liable to change by keeping, and yet there is no indication of this change in the appearance of the solution. as a test depends on the circumstance that when solutions of glucose are boiled with certain alkaline solutions of some salts of copper, the copper is reduced to the state of a yellowish or coppercolored insoluble suboxide in a practically fixed relation or proportion. When long kept the solution is liable to change, so that when diluted with water and boiled, the copper salt is reduced as if glucose was present, when it is not present. What this change is, or how or when it occurs, is not known, and therefore the rule is to dilute and boil the solution and allow it to partially cool to see whether there be any precipitation before the urine is added. And if there be a precipitation, to discard the solution for one more recently made. The writer knows of several instances in which the solution has remained perfectly good during several years, but also knows of many more instances wherein the same solution made from the same materials by the same formula, spoiled in a few months, and considerable quantities had to be thrown away.

To supply a solution which will certainly keep for any length of time, with accurate directions for using it, so that in ordinary inexpert hands it may not only be a trustworthy qualitative test for glucose, but approximately indicate the quantity of glucose present where the proportion is small,-is the object of this note. And the design is to treat the application of the test in such detail that any physican, pharmacist, student or trained nurse can follow the process step by step, and with a moderate number of trials reach results that are trustworthy and useful, though not critically accurate. This will not in all cases obviate the necessity for accurate examinations by experts, but will merely render such examinations infrequent, and serve to indicate when they are necessary. In all modern treatment of disease by well-trained physicans the careful watching of the urinary excretion is regarded as a prime necessity. Then, if this can be done, by processes which are simple and easy, with results close enough to be all that is practically needed in the large majority of cases, much time, labor and skill are saved, while the more complex and accurate processes which require expert skill are still in reserve for the small number of cases that require them. As long practiced by the writer, and now to be described, any physican, pharmacist, student or trained nurse can, after a few trials,

apply this test for glucose, and thus the physican's time may be saved by delegating the testing to any such assistants as he may have. But no one should be discouraged in the applications by a few failures at first, since everything worth knowing has to be learned through failures.

The formula used for many years by the writer for making Fehling's Solution is published in "Volumetric Analysis," by Francis Sutton, F. C. S., F. I. C., Phila. edition of 1882, p. 256. It is as follows:

per

For the Solution of Cupric Sulphate: Purified sulphate of copin granular crystals, air dried, is best adapted to this use. Weigh 69.28 grammes of the salt, dissolve it in a litre flask in about half a litre of distilled water, add 1 c. c of pure sulphuric acid and then distilled water to made the whole measure one litre at the ordinary work-room temperature. Transfer this to a stock bottle, and label it "Solution of Cupric Sulphate for making Fehling's Standard Copper Test Solution."

For the Solution of Alkaline Tartrates: Weigh 350 grammes of recrystallized sodio-potassic tartrate or Rochelle salt, put it in a litre flask and dissolve it in about 700 c. c. of distilled water. Filter the solution if necessary, and having returned it to the litre flask, add to it a clear solution of 100 grammes of caustic soda in about 200 c. c. of distilled water and make the whole measure a litre at the ordinary work-room temperature, by adding distilled water. Transfer the solution to a stock bottle, and label it "Solution of Alkaline Tartrates for making Fehling's Standard Copper Test Solution."

When ordinary sulphate of copper and Rochelle salt are dissolved in hot water and the solutions filtered hot and stirred while cooling, the salts are deposited in granular crystals, which are easily drained, washed and dried. Such purified salts make solutions which do not need filtration; and such only should be used for making Fehling's solution. The solution of caustic soda cannot be filtered, but must be allowed to settle clear. This is best done by making twice the quantity needed, and when clear, pouring off onehalf for present use; and by adding a similar quantity of soda and water to the remainder and setting it aside, after solution, it will be ready for the next making.

These solutions of Cupric Sulphate and Alkaline Tartrates when mixed in equal volumes make Fehling's solution, of which each c. c.

will contain 0.03464 gramme of cupric sulphate, which, under definite conditions, practically represents 0.005 gramme of pure anhydrous dextrose, glucose or grape sugar.

This Fehling's solution, diluted with an equal volume of water, may be boiled without change. But the addition to it of a very minute proportion of glucose causes a proportionate decomposition, and the final separation and deposit of suboxide of copper nearly proportionate to the glucose added.

In order to be in trustworthy readiness for use at all times, no matter how rarely or how frequently they may be wanted, the two solutions are put up separately. A 4 fluidounce=120 c.c. glass stoppered bottle of each solution, is put up in a pasteboard case with two test tubes and a 1 c.c. graduated pipette divided to fifths of a c.c., the bottles and case properly labeled, and having the following directions for use pasted on the box as a reminder to each person at the time he may use the test:

Application of Fehling's Solution.

Put into the test tube in the following order: First, 1 c.c. of the copper solution ;-next, 1 c.c. of water;-next, 1 c.c. of the solution of alkaline tartrates, and finally another 1 c.c. of water, and shake the mixture without applying the finger to the mouth of the test tube.

Boil the solution by holding the tube in an inclined positionfirst, over the small flame of a spirit or gas lamp, and when well heated, but not yet boiling, by holding only the side of the tube to the side of the flame.

After cooling for a minute or two the solution should remain perfectly transparent, and of the original sapphire blue color.

Then add 1 c.c. of the urine to be tested, mix well and boil the mixture with the same precautions as before, to prevent explosive boiling and loss of the test.

If the urine contains 1 p.c. or more of glucose, the liquid will lose its transparency and become of a dirty, greenish color as soon as it boils.

If it contains 0.25 p.c. of glucose it will usually remain transparent during the boiling, but the color becomes a lighter, dingy blue, with a greenish tinge. On cooling, during five or ten minutes, it assumes a dirty green opalescence and deposits suboxide of copper.

If it contains 0.1 p.c. of glucose it will remain transparent, or nearly so, of a light, dingy blue color, for half an hour to an hour

after boiling and then become cloudy, the clouds being of a dirty, greenish color. On longer standing the cloudy portions settle and leave a transparent blue solution above, and a minute quantity of reduced copper will be visible at the bottom of the tube.

Normal urine, or that which contains only a normal amount of glucose or other reducing agents, remains transparent throughout,— or very nearly so, but has the color changed to a somewhat inferior blue. This blue will, in many instances, have a greenish tinge, and a greenish fluorescence when seen by reflected light, but there will, in twenty-four hours, be no deposit of suboxide of copper visible to the naked eye.

As a quantitative estimation the above statements are roughly approximative only. The two solutions are accurately made, however, and when put together in exactly equal measures make the improved Fehling's solution as given in "Volumetric Analysis" by Sutton, 4th edition, Phila., 1882, p. 256,-each c. c., under definite conditions, being equal to 5 milligrammes of glucose. Hence the 2 c. c. taken for the above testing are equivalent to the 0.01 gramme of glucose, and that amount in 1 c.c. of urine is just 1 p. c.

Although as full and definite as is easily practicable, some explanation in detail seems almost necessary to an understanding of the application. The mixture when first boiled is, of course, Fehling's solution diluted with an equal volume of water. In measuring, the point of the pipette is dipped successively into the liquids, and the object of the prescribed succession is that the pipette may be well rinsed with the water between the dippings into the solutions, and that all of each measure of each solution may be transferred, by the rinsing, into the test tube. The copper solution is, of course, the most important to be kept accurate and free from all admixture, and hence it is measured first, when the pipette is perfectly clean and dry.

The proper and convenient use of the pipette is a matter of considerable importance, and although minim pipettes as well as c.c. pipettes have long been in use by means of rubber tips, for dosing medicines, etc., yet, it is believed, that very few persons use them in the best way. Hence it may be useful to describe the best way: Each pipette is supplied with a rubber tip,-or unperforated rubber nipple,-which fits over the upper end of the pipette, air-tight, but not so tightly as to prevent being easily slid up and down upon