571 



only be obtained after perhaps ten days of inquiry : and the quantity 

 observed in one season will not apply to that of any other season ; so 

 that the effect of season can only be ascertained by continued inquiries 

 through the year. Rest, diminished ingestion of fluid, increased 

 ingestion of animal solids, increased temperature and atmospheric 

 pressure, profuse discharges from the skin or bowels, and increased 

 bulk of the body from whatever cause, all other things being equal, 

 will lessen the excretion of urine. The contrary conditions, each one, 

 other things being equal, will increase the excretion of urine. The 

 action of any two of these agents, each in an opposite direction, will 

 modify the influence of the other. It must not be inferred that there 

 will be lessened excretion of urine because there is increased excre- 

 tion of fluid by other outlets, as the skin, unless it be proved that 

 there was no increase in the quantity of fluid ingested and no dimi- 

 nution in the bulk and weight of body. Urinary water is largely and 

 quickly excreted when fluid is drank without any solids having been 

 taken on that day, viz. before breakfast, but to a much less extent 

 if solids have been previously taken, and still less when solids 

 are taken with the fluid. The maximum rate of emission must be 

 sought for between the breakfast and 1 P.M., and by experiments 

 made not less frequently than a quarter of an hour. The mini- 

 mum quantities occur in the night, and continue for much longer 

 periods. All graduated glasses, alkalimeters, and pipettes should be 

 graduated and carefully proved by the observer before using them, 

 and this may be conveniently and most accurately effected by the 

 balance. 



In pursuing Liebig's volumetric method for the determination of 

 urea in the urine, it is essential that the operator have graduated 

 the mercurial solution himself, or have made himself familiarly ac- 

 quainted with the tint of colour to which it is graduated by repeatedly 

 testing it with the proper quantities of pure urea. Moreover, as the 

 recollection of the precise tint to which the solution was graduated 

 fades from the memory, the test quantity of urea should be used from 

 time to time to renew it. The urea to be used must be proved to be 

 perfectly pure. The solution should be made in a quantity of several 

 gallons, and be drawn from the carboy by a siphon with the smallest 

 apertures, so that the standard strength may be preserved. The 

 quantity in daily use for the supply of the alkalimeter should not 



