54: INTRODUCTION. 



following way : The blood, or tissue, finely divided, is boiled 

 with a little water and sulphate of soda. In a few moments 

 the organic and coloring matters will become coagulated, 

 "when it is to be thrown on a filter, and a clear extract will 

 pass through. This extract will contain sulphate of soda, 

 which is very soluble in hot water, but this does not interfere 

 with the application of the test. The same result may be 

 obtained by boiling with animal charcoal, enough being 

 added to make a thin paste, and filtering ; a process, how- 

 ever, which is more tedious and has no advantages over the 

 one just described. 



In testing the urine, a light flocculent precipitate will 

 generally be obtained, though no sugar be present. With 

 a little experience this may be distinguished from the 

 deposit of sub-oxide of copper, by the fact that it is less 

 highly colored, and appears in flakes after it finally settles 

 to the bottom of the test tube, of a light -grayish color ; 

 while the sub-oxide of copper settles to the bottom in the 

 form of a heavy red powder. If there be any doubt as to 

 the nature of the reaction, the urine may be purified in va- 

 rious ways before testing. A very simple, and perhaps the 

 best method, is to make a paste with animal charcoal and 

 filter. Robin recommends the following process: "To be 

 certain of the presence of glucose, we free it (the liquid) from 

 all reducing matters ; 1st, adding to the urine an excess of 

 the neutral acetate of lead, then filtering ; 2d, adding to this 

 clear filtered liquid, ammonia, until it is slightly alkaline, 

 and filtering. We can then treat the second liquid with the 

 reagents ; and if it precipitates, it is certain that there is sugar 

 in the urine." ' Another method is to evaporate the urine to 

 the consistence of a syrup, extract this with alcohol, drive 

 off the alcohol by evaporation, and dissolve the residue in 

 water ; when if sugar be present it will respond to the test. 



1 Dictionnaire de Medecine, etc., de P. H. NYSTEN, par E. LITTRE et Cn. ROBIN, 

 Paris, 1858. " Sucre." 



