28 THE SECRETIONS: 



somewhat problematic substance he gave the name of pepsin : 

 Wassmann 1 and Pappenheim 2 have endeavoured to isolate it. 

 (See Vol. I, p. 224.) 



Prout 3 has shown that the free acid of the gastric juice is 

 muriatic acid. Gmelin and Tiedemann 4 have found it associated 

 with acetic acid, and in the gastric juice of horses, with butyric 

 acid : there is no doubt that lactic acid is likewise contained in 

 it. From the researches of the latter chemists, which are the 

 most perfect that we possess on the subject, it appears that in 

 addition to the free acids, the gastric juice contains mucus, and 

 occasionally (in horses) a very small quantity of albumen, ex- 

 tractive and salivary matter, and that the ash consists of alkaline 

 muriates and sulphates, a little phosphate and sulphate of lime, 

 chloride of calcium, magnesia, and peroxide of iron. 



The gastric juice collected from the empty stomach, although 

 mixed with mucus, was tolerably clear ; it was neutral, of a 

 yellow colour, a saline taste, and on evaporation left only 2 of 

 solid constituents. Gastric juice obtained by irritating the 

 stomach with pebbles was acid, viscid, and of a pale brown 

 colour. Hiinefeld does not believe that there is any free hy- 

 drochloric acid in gastric juice. 



Berzelius analysed gastric juice collected by Beaumont from 

 a young man with a fistulous opening into the stomach. It 

 had been kept for five months before Berzelius received it, and 

 was therefore totally unfit for the purpose of analysis. In that 

 condition it was clear, yellow, devoid of odour, reddened litmus 

 paper in a decided manner, and left a solid residue of T269g, 

 consisting principally of crystals of chloride of sodium, in the 

 interstices of which was a brown extractive matter, which, on 

 exposure to the air, resolved itself into a dark brown thick 

 syrup. Its quantity was too small to admit of its being accu- 

 rately examined, but it was proved to contain lime and a proto- 

 salt of iron. Beaumont describes human gastric juice as a 

 clear, inodorous, saline, and very acid fluid, which effervesces on 

 the addition of alkalies. Dunglison detected in it free hydro- 

 chloric acid, an animal substance soluble in cold but not in 



1 De Digestione nommlla. Diss. inaug. Berol. 1839. 



2 Zur Kenntniss der Verdauung. Breslau, 1839. 



3 Philos. Transactions, 1824, p. 45. 



4 Die Verdauung nach Versuchen, p. 150. 



