12 t REPORT 1869. 



but the precipitate of uric acid being more coloured than in Nos. 1, 2, and 3, it 

 was further washed with boiling alcoliol, which removed 0-14 grain of colouring- 

 matter, and still left it darker than the others, retaining, thatis, more of the colouring- 

 matter. The weight of uric acid obtained in the four experiments was as follows :— 



No. 1. No. 2. No. 3. No. 4. 



Uric acid 7-44 7-80 9-50-2=7-50 7-30 grains. 



Two further experiments were made, in both of which the proportion of one 

 grain only of uric acid was superadded to the urine of twenty-four hours, the pro- 

 cess employed being the same in other respects as that of No. 1 in the preceding 

 experiments. The results were as follow : — 



1. Uric acid without addition = 7 -90 grains. 



,, „ with addition of one grain = S-74, or — 1 = 7-74 grains. 



2. Uric acid without addition = 7'G7 grains. 



„ „ with addition of one grain =8 -42, or- 1 = 7-42 grains. 



In the first of these two last experiments the alcoholic acid was decanted from the 

 precipitate previous to filtration after standing for only ninvti-en hours, and an 

 interval considerably less would probably sutfice. The uniformity of these results 

 deserve to be remarked. 



On the whole it appears that the best process for determining the quantity of 

 uric acid in urine is the following : — To neutralize a third or fourth part of the 

 urine of twenty-four hours, if alkaline with hydrochloric acid, or of acid with car- 

 bonate of potash, to reduce this to 1'5 fluid-ounce, to treat it with 3 drachms of 

 hydrochloric acid, combined with 1'5 fluid-ounce of alcohol, to decant when the 

 liquid is clear, to wash the deposit first with alcohol, and when that dissolves no 

 more, with equal parts of acetic acid and water ; and it also appears that the 

 amount of alkalinity in the urine, after being neutralized, does not effect the pre- 

 cipitate or detract from the accuracy of the determination. It may also be con- 

 cluded that notwithstanding the variability of the quantity of uric acid in dif- 

 ferent states of the system, if under imiform conditions of health and diet, expe- 

 riments be first made, in the manner described, on the natural urine, a sufficiently 

 exact average determination may be made of the normal quantity of uric acid an- 

 tecedent to the alkaline treatment, and that if the alkaline treatment subsequently 

 furnishes a grain or two more of uric acid, this may be relied upon as evidence 

 that the uric-acid calculus in the bladder is undergoing solution. 



Though the foregoing researches have failed to realize the expectation of testing 

 by analysis the effect of the solvent treatment on vesical calculus, a fact observed 

 during the whole course of that treatment, and not afteiT^-ards, appeared to indi- 

 cate that a solvent action was really going on. This fact consisted in a small but 

 constant amoimt of deposit, in which fragmentary particles of uric acid were 

 discerned by the microscope enveloped in mucus, resembling, in the opinion of Mr. 

 Spencer Wells, as well as of the author and his assistant *, tlie detritus left by the 

 incomplete action of carbonate of potash on uric-acid calculi, and such as might 

 have been washed out of the bladder in consequence of partial solution. That no 

 such solution should have been brought into evidence by the many determinations 

 of uric acid, however imperfect, here described, if it cannot be fully accounted for 

 by that imperfection, may possibly be due to a physiological effect of the alkaline 

 treatment in preventing the formation of uric acid, which may have counter- 

 balanced the excess expected from solution of the calculus. To ascertain these 

 points, as has been stated above, two sets of experiments are required, one in a case 

 in which calculus is prese7it, and one in which it is absent, in both of which the 

 process for determining the quantity of uric acid here recommended may be of use. 

 The author stated his conviction, from liis own experience of the effects of 

 citrate of potash not exceeding 300 grains taken in twenty-four hours, and pro- 

 ducing an alkalinity equalling from 20 to 35 grains of carbonate of potash con- 

 tinued during three months, that no disadvantage to health need be feared from 



* The author's laboratory assistant, Mr. William P. Horn, executed the experiments 

 detailed in this paper with great precision. 



