A surgical handbook : for the use of students, practitioners, house-surgeons, and dressers / by Francis M. Caird and Charles W. Cathcart.

Caird, Francis Mitchell, 1853-1926

Date:: 1889

Credit: A surgical handbook : for the use of students, practitioners, house-surgeons, and dressers / by Francis M. Caird and Charles W. Cathcart. Source: Wellcome Collection.

Provider: This material has been provided by The University of Leeds Library. The original may be consulted at The University of Leeds Library.

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$2.12 A Slfk'GJC.M. I/ANDHOUK. yiiished fi(jiii allnimcn unlil a few drfijis of nitric acid arc added, when the ])ii()s])iialcs will be dissolved, and alljunien, if jiresenli coaf»ulatcd. (^) Nilric Add.- Nitric acid is an extremely delicate test for albumen, and is the iirst test to use in all cases except when the urine Is turbid from urates. The best manner of applyinj^ it is to fill a tesl-tube to the depth of about an inch; then, inclining the tube, to pour in strong nilric acid in such a manner tliat it may trickle down along the side of the lui)e to the bottom, and form a stratum some <|uarter of an inch thick below the urine. Added in this manner, there is scarcely any mingling of the two fluids, and if albumen be present, three strata or layers will be ob.served —one jierfectly colourless, of nitric acid at the bottom; immediately above this an opalescent zone of coagulated albumen; and at the lop Ihe unaltered urine. If there be only a trace of albumen, twenty or thirty minutes elapse before the opalescent zone becomes visil)le. Ctiii/ion.s/- In concentrated urines, and especially in febrile urines, the addition o{ the acid is a]3t to precipitate the amorphous urates, and thus to occasion a turbidity which might 1)e mistaken for albumen. Albumen begins to coagulate immediately above the .stratum of acid, and the turbidity spreads upwards; but the urates first appc-ar at or near the surface of the urine, and tile opacity sjjreads downwards. Heat also readily resolves the douijt; for urates speedily disappear when llie m ine is warmed, l)ut turbidity fnjui albumen is not affecleil by heat. Nitric acid may increase the ojjalescence commonly present in the urine of jiatients who are taking cubeljs and copaiba. When excess of urea is present in the urine, nitric acid produces a crystalline deposit of nitrate of urea after tlie fluids have been some time in cf)ntact. 'loo small a (|iiantity of nitric acid will fail to coagulate the albumen ; a large tjuantity, if mixed with the urine, will re-dissolve it. (b.) Sugar—(a) .Moore'.': 'J'esl (Boiliili^ '.vith Liquor I'otaasi,-).— Add to the susjiected urine an equal quantity of liquor jiotassa.-, and boil in a test-tube. If sugar (more than 1^ gr. per ounce) be present, the mixture will be darkened and afterwards turned of a reddi.sh-brown colour. This is an easy though rough method, but is open to fallacy in high-coloured and in allnmiinous urines, and where tiie liciuor potassx becomes vitiated l)y the jiresence of lead from the glass bottles, as in these cases a darkening, independent of sugar, will occur. (/3) By llic Reduction of Oxide of Copper [with Fchliiig s Solution). — According to Roberts, this is the best method of detecting sugar in urine. It is described liy him as follows :— Pour some of the prepared test-liquor into a narrow test-tube to the depth of three-quarters of an inch ; heat until it begins to boil ; then add two or three drops of the .suspected urine. If sugar be abundant, a thick yellowish opacity and deposit of yellow suboxide are produced, and this changes into a brick-red at once if the blue colour of the test remain dominant. If no such reaction ensue, go on adding the urine until a bulk nearly equal to the test employed has been poured in ; heat again to ebullition ; and, no change occurring,$