AUSCULTATION. 525 



blowing a large number of soap-bubbles in a viscid lather. 

 This noise, which may be accompanied by a slight gurgling, 

 is best heard behind the shoulder in the median region; it 

 may also be heard over the lower end of the trachea. With 

 more rapid breathing, in bronchitis, when the secretion has 

 been well established in chronic bronchitis, or when pus 

 from a pulmonary abscess has been discharged into the 

 tubes the bubbles are of median size, and the sound cor- 

 respondingly modified. It may be imitated by blowing a 

 number of large and small soap-bubbles, so that they burst 

 simultaneously. The bubbles may burst separately, or a 

 number at once, so that the sound may be continuous. This, 

 which is sometimes called the sub-mucous rale, is heard 

 both in inspiration and expiration. When air passes through 

 fluid, in an enlarged bronchus or a pulmonary cavity, the 

 sound is modified accordingly, and takes the name of 

 cavernous. 



The crepitant rale is a very fine crackling sound, variously 

 likened to the crackling of common salt when subjected to 

 heat, to that caused by a sponge expanding in water after 

 having been compressed in the hand, or to the sound 

 developed by rubbing a lock of hair between the finger and 

 thumb close to the ear. It is developed exclusively in the 

 ultimate bronchial tubes or the air-cells, and is ascribed 

 either to the passage of air through a viscous mucus in the 

 former, or to the separation of the walls of the latter, which 

 have been agglutinated together by the same material. It is 

 only heard in inspiration, which would support the latter 

 opinion, and may be taken as a tolerably certain diagnostic 

 sign of pneumonia. By carefully auscultating, we find it to 

 precede the march of hepatisation in an inflamed lung, and 

 in a similar way the removal of the consolidation is followed 

 by a recurrence of the crepitant rale. In the latter case it 



