36 



DR. BASTIAIN^ ON THE 



were deposited. If the fluid is boiled slowly, the cloudiness thus 

 occasioned may be slight ; whilst in another vessel, whose contents 

 are more briskly boiled, the deposition is decidedly greater. Two 

 such fluids, ostensibly treated in the same way (that is, reported 

 as having been boiled for the same period), have really been treated 

 quite differently ; and they will probably show it by the different 

 periods at which fermentation supervenes ; only, contrary to what 

 usually occurs, in this particular case the one which has been 

 boiled most briskly and whose temperature has been raised to a 

 higher degree, will be the first to undergo change. 



(y) Now comes the question whether a boiled solution of 

 organic matter contained in a hermetically sealed vessel and kept 

 in a " warm place " is in a condition of unstable or of stable equi- 

 librium. Does it or does it not undergo modification ? Have we, 

 after an interval of fourteen days, to do with precisely the same 

 fluid as before, or with a fluid which is more or less different ? 



Dr. Eoberts argues as though it underwent no change ; I, how- 

 ever, have ascertained that urine does undergo most notable and 

 definite changes; and in 1872 I brought forward some facts ten d- 

 incf to show that other organic fluids gradually lapsed into a more 

 stable condition under the circumstances above indicated*. 



As it is the behaviour of urine which now specially interests us, 

 we had better for the present confine our attention to it. I will 

 therefore first refer to the changes which its principal constituent, 

 urea, is known to undergo when operated upon by heat of different 

 degrees of intensity. 



It has been long ascertained that urea is decomposed variously 

 by different degrees of heat. Thus, turning to the fifth edition of 

 Fownes's ' Manual of Chemistry,' published in 1854, I find at 

 p. 587 the following statement concerning urea : — " When heated 

 it melts, and at a higher temperature decomposes with evolution of 

 ammonia and cyanate of ammonia ; cyanuric acid remains, which 

 bears a much greater heat without change. The solution of urea 

 is neutral to test-paper ; it is not decomposed in the cold by 

 alkalies or by hydrate of lime, but at a loiling-heat emits ammonia 

 and forms a carhonate of the base.'" On the next page it is stated 

 that if urine in a recent state he long boiled, it gives off ammonia 

 and carbonic acid from the same source ^ 



* 'Modes of Origin of Lowest Organisms,' 1871, pp. 73 and 78, notes # & t, 

 and Expf . Ts'^o. xxxiii. 



