Formation of the Jcetoiis Acid in the Stomach. 353 



mentation is necessary to digestion, and that this fermenta- 

 tion may be either of a spirituous, an acid, or a putrid na-' 

 ture. Some alimentary substances even produce all these 

 three e fleets, as has been demonstrated by several observa- 

 tions. But, in general, each particular kind of food under- 

 goes that kind of fermentation which is most analogous to 

 its nature. • 



As we are acqiuinted with only one kind of spirituous 

 fermentation, and only one kind of the putrid, I shall not 

 speak of these two fermentations. But it is not the same 

 case with the acid fermentation, because it gives rise to se- 

 veral acids of different natures, which it is iinportant to 

 know in order to fix the opinions of chemists on the subject. 

 For this reason I detcnuir.ed to make the following experi- 

 ments upon myself: 



■ 1st, Knowing thai roasted chestnuts could not be digested 

 by my stomach without great diflicidty, and that they al- 

 ways created wind, followed, some monients atterwards, 

 with an insupportable sourness on the sluni:tch, I took 

 eight ounces of theni, which I ate without bread, after 

 having been for thirteen hours without tasting any thing, 

 and my stomach being perfectly empty. An hour and a 

 half afterwards I felt a swelling in my stomach (the usual 

 symptom with me after eating kernel su!)stances) : this 

 announced the pro.li\clion of some gas, wiiich I contrived 

 to collect in Lhe f)llowing manner:— I took a funnel with 

 a lonf lube, wliich I bent into a semicircle ; I placed the 

 small end of it in the pneumatic tub, on the shelf of which 

 there was a bell-glass filled with water; and I i;ad th\! pre- 

 caution to fill the tub with water, in order to cover the 

 whole of the tube of the fimntl, so that none of the gas 

 midu be lost which I nneht emit. Some minutes after- 

 wards I felt the dilatation in my stomach increase, and I 

 then belched up into the funnel the wind out of my stomacii 

 by applying my mouth to lhe funnel. I emnted, at ditfereiit 

 limes, a cubic inch of a gas which had all the characters ot 

 the carbonic acid, svhich nothing belied, and a liiilc atmb- 

 spluric air, which we always swallow with oiu- aliments, its 

 being necessary lo digestion. 



Z -J Tlie 



