GASTRIC JUICE. 393 



This extract contained osmazome, common salt, and acetate of po- 

 tash. 



The portion of the watery extract insoluble in alcohol was 

 merely a trace. It probably consisted of carbonate and phos- 

 phate of potash, and a small quantity of salivin. 



The matter which had been treated with cold water was boil- 

 ed in alcohol. The alcohol when evaporated left a substance 

 like tallow, whose alcoholic solution did not redden tincture of 

 litmus. 



The portion insoluble in alcohol, which constituted the princi- 

 pal part of the liquid of ranula, possessed the characters of co- 

 agulated albumen. 



It appears from this analysis, imperfect as it is, that the liquid 

 of ranula has no resemblance to saliva ; being destitute of sul- 

 phocyanic acid, and almost so of salivin, while it contains abun- 

 dance of albumen, which is not found in saliva. 



CHAPTER IV. 



OF THE GASTRIC JUICE. 



THE change which the food undergoes in the stomach was as- 

 cribed at first to the mechanical action of the stomach, but this 

 opinion was gradually abandoned, and chemical physiologists were 

 almost unanimous in assigning fermentation as the agent, though 

 what was meant by fermentation is far from clear. The nume- 

 rous experiments of Reaumur, Stevens, and Spallanzani, de- 

 monstrated that the change of food in the stomach was owing to 

 its solution in a liquid. This liquid was admitted to be secreted 

 in the stomach, and was therefore called gastric juice (succus 

 gastricus.) It seems needless to relate the attempts to collect this 

 liquid by Spallanzani, Gosse, Brugnatelli, Carminati, &c. be- 

 cause they were unsuccessful. The first important step to de- 

 termine its nature was by Dr Beaumont of the United States 

 army. He has published a very interesting set of experiments 

 on the human gastric juice,* which tend to throw a great deal of 



* The original work, entitled " Experiments and Observations on the Gas- 

 tric Juice and the Physiology of Digestion," was published in America in 1833. 

 A new edition, edited by Dr Combe, appeared in Edinburgh in 1838. 



