332 



Prof. F. Smith. 



[June 20, 



work are 232*157 grams, the organic solids 152*190 grams, and the 

 ash 79*967 grams. Great variation both at rest and work is observed 

 in the total solids, even where the diet remains the same. 



The nature of the diet, according to Tereg,* considerably influences 

 the amount of the urinary solids excreted, as shown in the following 

 table : — 



Daily ration. 



Hay. 



Oats. Wheat straw. 



8 kilos. 



2 kilos. 





566*0 



7 „ 



2 „ 



1 kilo. 



529 *4 



6 „ 



4 „ 





511-8 



4 „ 



4 „ 



2 kilos. 



477*0 



4 „ 



6 „ 





460 7 



1 



6 „ 



2'6 „ 



346 -1 



Solids in the urine, 

 grams. 



About 90 per cent, of the ash is soluble in water, and 10 per cent, 

 soluble in acid. In the watery solution of ash we find the chlorides 

 of sodium and potassium, traces of lime, phosphates, magnesia, and 

 sulphates. In the acid solution lime, magnesia, and sulphates pre- 

 dominate. On looking at the inorganic solids, they are smaller than 

 I had expected ; the extreme difficulty experienced in incinerating 

 urinary solids causes, undoubtedly, a loss by the volatilisation of the 

 chlorides, &c. 



Urea. — In calculating the urea we have also to take into considera- 

 tion the carbonate of ammonia which unavoidably forms during the 

 twenty-four hours the urine is being collected. 



To show bow much of the urea breaks up owing to fermentation, 

 I have calculated it separately in the table, and then added the two 

 together. I used Liebig's method of determination for some time, 

 but it gives too high results. 



My most trustworthy observations have been made with the hypo- 

 bromite process. 



The influence of rest and work over the production has been most 

 carefully studied. 



I originally held the view that more urea was excreted during work 

 than during rest, and a long series of analyses supported this view. 

 I found, in fact, in tabulating my results that the resting horses 

 excreted on an average 88*41 grams of urea daily, of which 13' 778 

 grams were in the form of ammonia carbonate; whilst working 

 horses excreted 134*9291 grams, of which 12*4591 grams existed as 

 ammonia carbonate. 



The incorrect conclusions which appeared forced on me were due 

 to the fact that the excretion of urea, even on a fixed and rigid diet, 

 is extremely variable, and in the horses from which the above results 



* ' Encyklopadie der Gresammten Thierheilkunde,' vol. 4. 



