CHEMICAL SCIENCE. 187 



NEW SPECIES OF SUGAR. 



M. LAURENT, in the Compfcs Rendus, Jan. 1, describes a new spe- 

 cies of sugar, to which he gives the name Dulcose. It comes from 

 Madagascar, but its origin is not well known. It crystallizes in oblique 

 rhombic prisms, possesses a slight sweetish taste, and diffuses upon 

 incandescent charcoal the same odor as sugar. From its composition 

 it is homologous with grape-sugar, and like grape-sugar acts the part 

 of a weak polybasic acid. According to M. Bior, it exerts no action 

 upon polarized light; and according to M. Soubsiran, it does not un- 

 dergo alcoholic fermentation. 



o 



NEW TEST FOR THE DETECTION OF THE PRESENCE OF SUGAR 

 IN CERTAIN LIQUIDS, AND ESPECIALLY IN URINE. 



SEVERAL processes have been described by chemists for the detec- 

 tion of sugar, even under the singular circumstances of diabetic dis- 

 ease. Unfortunately, none of the processes are of such simple execu- 

 tion as to be readily adopted by the medical profession. I now present 

 chemists and physicians with a test by means of which the presence 

 of the smallest quantity of sugar can be detected in an instant. By the 

 action of chlorine upon sugar there is found a brown substance, which 

 is partially soluble in water, a caramel, which is of a brilliant black 

 color when dried. This effect produced by chlorine is obtained as ea- 

 sily, if not more so, with the chlorides, and especially with the per- 

 chlorides. All sugars behave like cane-sugar towards the chlorides ; 

 they experience a dehydration, the result of which is the brownish- 

 black product. From these facts we learn the conditions under which 

 we must place ourselves in order to obtain a reagent capable of detect- 

 ing the presence of sugar. Let us suppose, in fact, a slip of solid sub- 

 stance, which is not altered by the chloride of tin even at a high tem- 

 perature ; cover this substance with a layer of chloride by immersing it 

 in a concentrated solution and desiccating it ; then dip the slip thus 

 prepared in a very dilute solution of sugar, and expose it to a tempera- 

 ture of from 268 to 300 F. The part which has been immersed will 

 immediately change color and become of a brownish-black, more or less 

 deep. The substance best suited for receiving the coating of chloride 

 of tin is white merino cloth. After having dipped the merino for three 

 or four minutes in an aqueous solution of bichloride of tin, let the liquid 

 drain off, dry the cloth in a piece of the same substance on the water- 

 bath, and the reagent is prepared. It may then be cut into strips like 

 ordinary test-papers. By means of this chlorinated merino, the physi- 

 cian will be able, without the least difficulty, to determine whether the 

 urine of the patient contains an appreciable trace of sugar. It will be 

 sufficient to pour one drop of the urine upon one of these strips, and to 

 hold it over the flame of a lamp, or incandescent charcoal, to produce 

 in an instant a very visible black stain. The sensitiveness of the test 

 is wonderful ; 10 drops of a diabetic urine, added to 100 cubic centi- 

 metres of water, furnish a liquid which turns the chlorinated merino 

 completely brownish -black. Ordinary urine, urea, and uric acid are 



