113 



gas which hastens the approach of death, by impeding the descent of the 

 diaphragm. 



Digestion, when healthy, is unaccompanied by the production of gases. 

 In indigestion, there almost always escapes carbonated or sulphureted 

 hydrogen gas, which produces the offensive smell of the air which es- 

 capes at the anus: this smell is different from that of the flatus which are 

 brought upwards, these contain pure hydrogen or carbonic acid gas. The 

 latter is, likewise, sometimes voided by the rectum, but less frequently 

 than hydrogen combined with carbon, sulphur, or even phosphorus. Is 

 not ammonia itself extricated, and does it not accompany the evacuation 

 of the faeces in certain putrid diarrhoeas, as indysg|tery combined with 

 low fever ? Though the formation of this gas implies a putrefactive mo- 

 tion opposed to the vital principle, may not this decomposition com- 

 mence in substances lying in the great intestines, when these are be- 

 come almost inert from the impaired condition of the vital power. This 

 would riot be the only instance of a chemical process taking place in the 

 intestinal canal, notwithstanding the counteracting influence of vitality. 

 Thus, on some occasions, grapes eaten in too great quantity, ferment and 

 produce carbonic acid gas, in such abundance, that this elastic fluid over- 

 comes the resistance of the intestines. This is the kind of distension 

 from flatulence which is cured by drinking plentifully of cold water, 

 which dissolves the gas naturally soluble in that fluid. 



XXXI. Of f/ie secretion and excretion of the Urine. The fluids absorb- 

 ed with the chyle, and taken up by the lymphatics of the intestinal tube, 

 dilute the nutritive part extracted from the solid aliment, and serve it as 

 a vehicle. When they have reached the mass of the bfood, they increase 

 its quantity, diminish its viscidity, and render it more fluid ; going along 

 with it throughout the whole course of the circulation, they supply moist- 

 ure to all the parts of the body, and become loaded with the molecules 

 detached from them by the vital motion. Then, conveyed to the urinary 

 organs, they become disengaged from the rest of the fluids, carrying 

 along with them a number of products of every kind, which by a longer 

 stay in the animal economy, would not fail to occasion a manifest distur- 

 bance in the exercise of the functions. 



XXXII. The rapidity with which we void, with the urine, certain diu- 

 retics, has induced several physiologists to think, that there exists a di- 

 rect communication between the stomach and bladder: no one, however, 

 has ever succeeded in pointing out those peculiar ducts, which might 

 serve to convey the urine from the stomach to the urinary organs, with- 

 out taking the circuitous course of absorption and of the circulation, and, 

 besides, the learned Haller has proved, by accurate calculations, that the 

 size of the renal arteries, 'whose calibre amounts to an eighth of that of 

 the aorta, and the quickness with which che blood flows, sufficed to ac- 

 count for the shortness of the time in v-nich certain fluids reach the uri- 

 nary organs*. 



* The experiments of Dxnwnr wit* the nitrate of potash, and of BRAND B with the 

 prussiate of potash, have led severs'* i' 1 modern times, and amongst these, Sir EVERARD 

 HOME, to support the opinion allied to above. MAGENDIE made experiments in order 

 to ascertain this matter, and deuced from them the following inferences : 



1. Whenever the prussiate of potash is injected into the veins, or absorbed from the 

 Intestinal canal, or from a jerous surface, it passes quickly into the bladder, where it 

 may be easily recognized m the urine. 2. Whenever a very considerable quantity of 



P 



