38 



DR. BASTIAN ON THE 



blue, showing that some ammonia is being given off sufficient to 



make the steam from acid urine faintly alkaline, 



I then proceeded to make some quantitative determinations as 



to the amount of diminution of acidity occasioned by boiling urine 



both in an open vessel and, under pressure, in a closed vessel — 



also as to the subsequent rate of change when urine was kept 



at different incubating-temperatures. Accidents happened to 



some members of the first series which I prepared with the 



view of throwing light upon this subject. The results ascertained 



from three of the vessels which escaped were, however, sufficiently 



significant to show the importance of the inquiry : — 



Eesult. 

 1. Fluid found to have 

 been diminished by 5iij. 



Acidity of remainder neu- 

 tralized by minims of 



Treatment. 

 1. One fluid-ounce of the 

 acid urine was boiled in a 

 retort with a capillary neck 

 for 5" over the flame pretty 



Urine whose aci- 

 dity was exactly 

 neutralized by viii^ 

 minims of liquor 

 potassse to the 

 fluid-ounce. 



liquor potasste. 



2. Fluid diminished by 5|. 

 Acidity of remainder neutra- 

 lized by vj minims of liquor 

 potassse. 



3. Fluid diminished by 5:^. 

 Acidity of remainder neutra- 

 lized by iv minims of liquor 

 potassae. 



briskly, but without spurting- 

 away of fluid. 



2. One fluid-ounce of same 

 boiled gently over flame 2" 

 and in can of water, after 

 sealing, for 18" 



3. One fluid- ounce of same 

 boiled gently over flame 2" 

 and in can of water, after 

 sealing, for 8 " . Th en placed 



I in incubator at 122° F. for 6 

 I days. 



These estimations, confirmed as they have been by others, soon 

 let in a flood of light. The great diminution of acidity caused by 

 brisk boiling in an open vessel with a capillary orifice was remark- 

 able, and is doubtless principally attributable to the fact that 

 under these conditions the temperature of the fluid is easily raised 

 three or four degrees of the Centigrade scale above the boiling- 

 point ; the loss of acidity involved in the diminution of the fluid 

 itself by the mere process of boiling, but without appreciable 

 spurting, was probably small*. But when both these conditions 

 are obviated as much as possible by gentle boiling over the flame 

 for two minutes only, and by continuing the exposure to heat, 

 after the vessel has been sealed, in a can of boiling water at a de- 

 finite temperature of 212° F., the total period of heating may be 

 four times as long without causing as much diminution of acidity 

 as was found in the five minutes of brisk boiling over the flame. 

 Then, again, it appears from the third experiment that the trans- 



^ See a communication by Dr. Frankland, Proceed, of Eoyal Society, No. 

 178 (1877), vol. XXV. p. 542. 



