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"PICRIC ACID AND SUGAR TESTING."
959 in Council of April Ist, 1881, Fleet Surgeon George William John Sutherland has been placed on the Retired List from the 20th ult.; Surgeon John Christian has been placed on the Retired List of his rank from the 16th ult. The following appointments have been made : - Fleet Surgeons Chas. A. Lees, M.D., to the President, additional, vice Jackson, promoted ; James Flanagan to the Duke of Wellington, vice Lees ; and Stephen Sweetnaor, to the Defence, vice Flanagan. Staff-Surgeon Edward W. Doyle to the Valiant, vice Sweetnam.
Correspondence. " Audi alteram partem."
"PICRIC ACID AND SUGAR TESTING." To the Editor of THE LANCET. am SIR,—I sorry to have anything to say to detract from the value of the "happy accident" through which, on the morning of the 14th inst., Dr. Johnson, whilst using picric acid as a test for albumen, came upon what he believed to be an extremely sensitive test for grape sugar whether in the - urine or elsewhere; but I cannot allow his letter upon the subjfct in your issue of the 18th to pass without a few comments upon it. I have followed the directions given by Dr. Johnson, and the results of my own observations upon the employment of picric acid as a test for sugar stand thus :-When equal volumes of a saturated solution of picric acid and liquor potassa3 are mixed a bulky precipitate of the comparatively insoluble picrate of potash is formed. If now the contents of the test tube are boiled, the precipitate disappears, and a ruby colour is developed. This change occurs without the addition of anything to the mixed picric acid and potash. On next pouring in some healthy urine and further boiling, a notably deeper colour, now amounting to a claret red, is produced, and if the urine should be a concentrated specimen, the depth of colour may be very intense-so much so as to approach towards an appearance of black on being viewed by reflected light, but transmitted light shows it to be a deep claret red. If, instead of healthy urine, some diabetic urine be poured into the mixture of picric acid and liquor potasssæ, a very dark colour is, on boiling, at once assumed, which appears almost, or it may be quite, black by reflected light ; but it nevertheless, as shown by transmitted light, aud also by diluting the product with water, consists of the same claret red character as in the other instance. Without the addition of any foreign agent, then, to the picric acid and potash, boiling produces a certain amount of colour, healthy urine increases this, and diabetic urine inThe same kind of tint is throughout creases it further still. manifest. There is only a difference in the degree of colour produced, and by diiution with water the deep-coloured product yielded by the diabetic urine may be brought to resemble, so as to be undistinguishable, the test treated with healthy urine and the test taken alone. Dr. Johnson suggests that the effect of picric acid is to intensify the colour produced by the reaction of caustic potash and grape sugar-the reaction known as Moore’s test. If we refer, however, to "Watts’ Dictionary of Chemistry," we find that the actiou of reducing agents upon picric acid is to lead to the production of picramic acid, which is a red-coloured principle. Various reducing agents are named which convert picric into picramic acid, and amongst them are the sulphides of ammonium, potassium, &c., which are susceptible of beiog generated by boiling urine with potash. The colour by boiling the mixture of picric acid and potash with a sulphide so resembles that produced by boiling it with healthy and diabetic urine that, as the result of observation, I coutd not distinguish any difference when brought to the proper extent of dilution, and I think it may be considered that the effect of grape sugar is to act as reducing agent upon the picric acid instead of the picric acid intensifying the action ofpotash upongrape sugar. A few words upon the subject of exrent of sensitiveness that it is desirable for a. test for sugar to possess looked at in relation to its employment as a qualitative clinical test. I believe it would be an absolute misfortune for a more sensitive test than the cupric test to be introduced into
developed
What is wanted for medical purposes is not to the E-i-nall fluctuating amount of sugar existing in healthy urine, but sugar when it reaches an amount to be of clinical significance. The ammoniated cupric test, which has been described by me and which I employ for quantitative purposes, and which is so sensitive as with the greatest facility to reveal not only the sugar but the amount of sugar existmg in healthy urine, would be an exceedingly
general use.
recognise
dangerous agent to employ asa qualitative test. HadInotbeen stronglyimpressed with this I should have long since introduced it to notice as a qualitative as well as aquantitative tet. A good form of cupro-potassic test furnishes, I consider, exactly what is wanted by medical men. It resists being influenced by, or rather does not show the effect exerted by, the sugar present in healthy urine, but does reveal the presence of sugar when existing to an extent to be of clinical significance. A cupro-potassic test, if kept in solution for some time, loses its stability and becomes too easily influenced to be relied cautionary measures are taken.
upon, unless certain preI feel that I ought to be about the cupric test pellets
some reserve in speaking (supplied by Mr. Cooper of 26, Oxford-street as they originated with me; but, at the same time, I believe I am serving the interests of medical practitioners in stating that experience has led me to regard them as supplying the safest
under
test that
can
be used.
I am, Sir, yours, &c., F. W. PAVY.
P.S.—Will you allow me to add under the form of postthe letter which I sent you last week, and which reached you too late for insertion then, a few remarks suggested by the further communication contained in your last issue from Dr. Johnson. Appended to Dr. Johnson’s letter is a communication from his son, which bears the impress of careful observation as far as it goes. Mr. G. Stillinafleet Johnson confirms what I have mentioned about potash alone and healthy urine giving the colour produced by sugar, and he enumerates several precautions as being necessary in the use of the test. He fails, however, to say anything about the effect produced by the presence of sulphides, which is identical with that produced by sugar.
script to
The sulphide produced by boiling albumen with potash suffices to give a deep colouration. Let some thoroughly washed precipitated albumen be dissolved in a boiling solution of potash and then a little of this be boiled with the mixture of potash and picric acid ; the result observed is a deep colouration like that produced by sugar. I expect in Dr. Johnson’s original observation on the two specimens of albuminous urine the albumen had something to answer for in the result he noticed. Again, a small piece of white flannel which represents hair may be boiled and dissolved in potash ; a little of the liquid added to and boiled with the picric acid and potash gives an exceedingly strong behaviour. These are illustrations of how a reaction may be produced by a sulphide derived from the action of potash upon organic principles, and that a sulphide is actually produced by the action of potash upon the constituents of healthy urine is shown by the well-known fallacy that Moore’s or the liquor potassæ test is open to from the presence of a little lead. Thus as a means of displaying the presence of sugar in healthy urine which Dr. Johnson lays stress upon, the indication is mixed up with error. Neither for qualitative nor quantitative purposes in relation to clinical utility do I consider the behaviour of picric acid and potash suitable for being turned to account as a test for sugar. Certainly as far as applicability to the requirements ot the medical practitioner is concerned, I think it will be found that the discovery which Dr. Johnson so hastily communicated to vou will prove devoid of value.
"SCURVY." To the Editor of THE LANCET. SIR,—I have read with interest the letters of Dr. MacDowall and Dr. Lucas on ’’ Scurvy," which appeared iu THE LANCET last week. I should like, however, to m tke a, few remarks which, I think, will lessen the discrepancy that they both point out, as appearing to exist between Dr. Parkes and myself with regard to the antiscorbutic properties of lactic acid. Dr. MacDowall observes that Dr. Parkes "teaches that lactic acid simply goes to form alkaline carbonates in the
Correspondence. " Audi alteram partem."
"PICRIC ACID AND SUGAR TESTING." To the Editor of THE LANCET. am SIR,—I sorry to have anything to say to detract from the value of the "happy accident" through which, on the morning of the 14th inst., Dr. Johnson, whilst using picric acid as a test for albumen, came upon what he believed to be an extremely sensitive test for grape sugar whether in the - urine or elsewhere; but I cannot allow his letter upon the subjfct in your issue of the 18th to pass without a few comments upon it. I have followed the directions given by Dr. Johnson, and the results of my own observations upon the employment of picric acid as a test for sugar stand thus :-When equal volumes of a saturated solution of picric acid and liquor potassa3 are mixed a bulky precipitate of the comparatively insoluble picrate of potash is formed. If now the contents of the test tube are boiled, the precipitate disappears, and a ruby colour is developed. This change occurs without the addition of anything to the mixed picric acid and potash. On next pouring in some healthy urine and further boiling, a notably deeper colour, now amounting to a claret red, is produced, and if the urine should be a concentrated specimen, the depth of colour may be very intense-so much so as to approach towards an appearance of black on being viewed by reflected light, but transmitted light shows it to be a deep claret red. If, instead of healthy urine, some diabetic urine be poured into the mixture of picric acid and liquor potasssæ, a very dark colour is, on boiling, at once assumed, which appears almost, or it may be quite, black by reflected light ; but it nevertheless, as shown by transmitted light, aud also by diluting the product with water, consists of the same claret red character as in the other instance. Without the addition of any foreign agent, then, to the picric acid and potash, boiling produces a certain amount of colour, healthy urine increases this, and diabetic urine inThe same kind of tint is throughout creases it further still. manifest. There is only a difference in the degree of colour produced, and by diiution with water the deep-coloured product yielded by the diabetic urine may be brought to resemble, so as to be undistinguishable, the test treated with healthy urine and the test taken alone. Dr. Johnson suggests that the effect of picric acid is to intensify the colour produced by the reaction of caustic potash and grape sugar-the reaction known as Moore’s test. If we refer, however, to "Watts’ Dictionary of Chemistry," we find that the actiou of reducing agents upon picric acid is to lead to the production of picramic acid, which is a red-coloured principle. Various reducing agents are named which convert picric into picramic acid, and amongst them are the sulphides of ammonium, potassium, &c., which are susceptible of beiog generated by boiling urine with potash. The colour by boiling the mixture of picric acid and potash with a sulphide so resembles that produced by boiling it with healthy and diabetic urine that, as the result of observation, I coutd not distinguish any difference when brought to the proper extent of dilution, and I think it may be considered that the effect of grape sugar is to act as reducing agent upon the picric acid instead of the picric acid intensifying the action ofpotash upongrape sugar. A few words upon the subject of exrent of sensitiveness that it is desirable for a. test for sugar to possess looked at in relation to its employment as a qualitative clinical test. I believe it would be an absolute misfortune for a more sensitive test than the cupric test to be introduced into
developed
What is wanted for medical purposes is not to the E-i-nall fluctuating amount of sugar existing in healthy urine, but sugar when it reaches an amount to be of clinical significance. The ammoniated cupric test, which has been described by me and which I employ for quantitative purposes, and which is so sensitive as with the greatest facility to reveal not only the sugar but the amount of sugar existmg in healthy urine, would be an exceedingly
general use.
recognise
dangerous agent to employ asa qualitative test. HadInotbeen stronglyimpressed with this I should have long since introduced it to notice as a qualitative as well as aquantitative tet. A good form of cupro-potassic test furnishes, I consider, exactly what is wanted by medical men. It resists being influenced by, or rather does not show the effect exerted by, the sugar present in healthy urine, but does reveal the presence of sugar when existing to an extent to be of clinical significance. A cupro-potassic test, if kept in solution for some time, loses its stability and becomes too easily influenced to be relied cautionary measures are taken.
upon, unless certain preI feel that I ought to be about the cupric test pellets
some reserve in speaking (supplied by Mr. Cooper of 26, Oxford-street as they originated with me; but, at the same time, I believe I am serving the interests of medical practitioners in stating that experience has led me to regard them as supplying the safest
under
test that
can
be used.
I am, Sir, yours, &c., F. W. PAVY.
P.S.—Will you allow me to add under the form of postthe letter which I sent you last week, and which reached you too late for insertion then, a few remarks suggested by the further communication contained in your last issue from Dr. Johnson. Appended to Dr. Johnson’s letter is a communication from his son, which bears the impress of careful observation as far as it goes. Mr. G. Stillinafleet Johnson confirms what I have mentioned about potash alone and healthy urine giving the colour produced by sugar, and he enumerates several precautions as being necessary in the use of the test. He fails, however, to say anything about the effect produced by the presence of sulphides, which is identical with that produced by sugar.
script to
The sulphide produced by boiling albumen with potash suffices to give a deep colouration. Let some thoroughly washed precipitated albumen be dissolved in a boiling solution of potash and then a little of this be boiled with the mixture of potash and picric acid ; the result observed is a deep colouration like that produced by sugar. I expect in Dr. Johnson’s original observation on the two specimens of albuminous urine the albumen had something to answer for in the result he noticed. Again, a small piece of white flannel which represents hair may be boiled and dissolved in potash ; a little of the liquid added to and boiled with the picric acid and potash gives an exceedingly strong behaviour. These are illustrations of how a reaction may be produced by a sulphide derived from the action of potash upon organic principles, and that a sulphide is actually produced by the action of potash upon the constituents of healthy urine is shown by the well-known fallacy that Moore’s or the liquor potassæ test is open to from the presence of a little lead. Thus as a means of displaying the presence of sugar in healthy urine which Dr. Johnson lays stress upon, the indication is mixed up with error. Neither for qualitative nor quantitative purposes in relation to clinical utility do I consider the behaviour of picric acid and potash suitable for being turned to account as a test for sugar. Certainly as far as applicability to the requirements ot the medical practitioner is concerned, I think it will be found that the discovery which Dr. Johnson so hastily communicated to vou will prove devoid of value.
"SCURVY." To the Editor of THE LANCET. SIR,—I have read with interest the letters of Dr. MacDowall and Dr. Lucas on ’’ Scurvy," which appeared iu THE LANCET last week. I should like, however, to m tke a, few remarks which, I think, will lessen the discrepancy that they both point out, as appearing to exist between Dr. Parkes and myself with regard to the antiscorbutic properties of lactic acid. Dr. MacDowall observes that Dr. Parkes "teaches that lactic acid simply goes to form alkaline carbonates in the