BY DR. LAUDER BRUNTON. 







investigated body, indigo-red, which has already been alluded 

 to. 1 



The following reactions may be tried with indigo-blue : 

 (a) Shake a fragment of indigo-blue with ether ; the sub- 

 stance is found to be very scantily soluble. Ether, however, 

 dissolves enough to acquire a faint blue tint. 



(6) Place a fragment in a narrow glass tube and heat ; it 

 will sublime and be deposited in the cool part of the tube. 

 the latter be very narrow and thin, it may be examined 

 microscopically. The sublimate of indigo is then seen to con- 

 sist of microscopic needles and plates. 



METHODS FOR THE QUANTITATIVE ANALYSIS OF UKINE. 



** 190. Determination of the total quantity of Urine 

 passed in a given time. Before describing briefly the 

 methods which are empk^ed for the determination of the more 

 important urinary constituents, attention must be drawn to 

 the fact that, as a general rule, quantitative analysis of urine 

 throws little or no light on the rate and character of the tis- 

 sue changes going on in the animal body, unless the analysis 

 be made of a specimen of urine which represents the average 

 excretion of a known period, during which the conditions of 

 the animal have been ascertained as accurately as possible. 



These remarks will be better understood when it is stated 

 that we can obtain the .most valuable information relating to 

 the urinary secretion if we collect, mix, and then measure the 

 whole of the urine passed in twenty-four hours. Having 

 ascertained the total volume of urine passed in twenty-four 

 hours, two hundred cubic centimetres will suffice for the great 

 majority of quantitative analyses. 



The urine of man must be collected in perfectly clean glass 

 vessels which in accurate experiments, should, before being 

 used, be washed with dilute sulphuric acid, and then with 

 water. The collecting-vessel may be graduated or not ; in the 

 latter case, the urine is carefully poured, if necessary, in suc- 

 cessive portions, after being mixed, into a cylinder capable of 

 holding a litre of water, and divided into 200 parts ; so that 

 each division indicates 5 cubic centimetres. 



It is frequently of use to collect the urine of dogs and rab- 

 bits, especially when experiments are made on the physiological 

 action of drugs. 



1 In many cases of disease, urine contains so much indican, that the 

 following reaction may be observed : 



To five cubic centimetres of fuming hydrocbloric acid, add from one 

 to two cubic centimetres of urine. A violet color is produced, which 

 passes into red. 



