TRANSACTIONS OF THE SECTIONS. 117 



the fluids of the mouth is demonstrated by the decay taking place in 

 those situations where these fluids are longest detained, as between the 

 natural teeth, and most frequently in the back teeth and in those of the 

 lower jaw, or on those parts of artificial teeth where the ligature, wire, 

 or pivots are employed for fastening them. 



It is difficult to explain the manner in which the fluids of the mouth 

 act on the teeth. It is evidently not by an acidity of the secretions of 

 the mouth, which would dissolve the earthy part instead of afl^ecting 

 the animal substance of the teeth. There is every reason for believing 

 that the state of digestion influences the secretions of the mouth, and 

 prepares them for acting on the teeth. The qualities of the food seem 

 to have considerable eflfect. Some nations, as the Americans and the 

 French, sufl^er from decay of the teeth even at an early age, while some 

 other people scarcely ever lose their teeth by the process of decay. 

 Mechanic trituration has no efliect in producing decay. The inhabitants 

 of Greenland, who chew the tough skin of the whale, have their teeth 

 worn to the stumps, which are nevertheless perfectly sound. 



On the Chemistry of the Digestive Organs. Sy RobeetD.Thomson,M.Z>. 



Having shortly reviewed the progress of knowledge on the chemical 

 actions which take place in the stomach, the author proceeded to the 

 further consideration of the subject under two heads : 



I. Chemical state of the stomach: 1st, in health; and, 2ndly, in 

 disease. 



II. The chemical state of the mouth and oesophagus in health and 

 disease. 



I. 1st. He noticed Dr. Front's discovery of free muriatic acid in the 

 stomach during the excitement produced in it by digestion. The author 

 mentioned the successful repetition by himself of an experiment of M. 

 Blondelet, in which a substance similar to chyme had been prepared by 

 digesting muscle in dilute muriatic acid at the temperature of the human 

 body. He found, on repeating the experiment by digestion at a tem- 

 perature of about 100° in the sand bath during ten hours, the fibre still 

 retained a portion of its original colour. From these facts it may be 

 inferred that free muriatic is an important auxiliary in the process of 

 digestion. 



2nd. The most common departure from the natural state of the sto- 

 mach is a redundancy of acid, occasioned by the introduction of acid 

 fruits and by the fermentation of vegetable matter. This form of d)'^s- 

 pepsia is sufficiently well known under the common name of heart-burn. 

 But the author showed that an alkaline state often exists which has 

 hitherto been unobserved. He showed that pyrosis, or water brash, con- 

 sists essentially of an alkaUne secretion, instead of the natural acid se- 

 cretion. A detail of the chemical analysis of the fluid emitted from the 

 stomach in that disease showed that the alkali present was ammonia, 

 and probably also free soda : 150 grs. were evaporated in a platinum 

 crucible ; when reduced to one third of its original bulk, the fluid con- 



