CHAP. II.] THE PRINCIPLE OF URINE. 157 



foolish notion having got abroad as to the small 

 quantity of acrid matter contained in the urine of 

 the horse, induced Dr. Thomson * to submit a 

 portion of it to chemical analysis in order to decide 

 that point. " The result was, that it was found to 

 contain an unusually large proportion of that prin- 

 ciple, so that without being concentrated by eva- 

 poration, it yielded crystals of nitrate of urea, very 

 readily on the addition of nitric acid." This fact 

 being thus satisfactorily ascertained/ accounts for 

 the strong ammoniacal vapour of stables that affects 

 the eyes of the attendants, and being inhaled (as 

 said in section 39.), is clearly the harbinger of 



• Of Edinburgh, in bis Annals of Philosophy, for August, 1020. 

 By the way, on this subject it is worthy of remark, that for seve- 

 ral years past, the French and Italian doctors have made a great 

 fuss about this Vuree (urea), or proportion of the principle of piss, 

 calling it " a discovery ;" whereas our own people, in every branch 

 of medicine, have been acting upon the same doctrine for better than 

 forty years, to our certain knowledge. Some have regulated their 

 practice (human) by the appearance of the water, with various suc- 

 cess ; and I have a great notion, that this test of the state of the 

 horse's health may be added to those other symptoms by which we 

 endeavour to ascertain the ailments of an animal which nature has 

 forbidden to complain. Whatever practitioner should undertake to 

 judge of the horse's diseases by its urine, must prepare himself to 

 undergo a good deal of ridicule, and may expect some calumny ; he 

 would not, however, be far from the right path towards making a 

 proper estimate of the quantity or violence of its ailment, though he 

 might not so readily ascertain the precise nature of the disorder. 

 The terms " nephrin" and " uric acid," the oldest and the newest 

 for the principle of this evacuation, show the assiduity of which it has 

 been deemed worthy, in that practice where it is confessedly of less 

 importance than it is in ours. 



