ITS CONSTITUENTS. 45 



In addition to lactic acid, the solid residue of the gastric juice 

 contains an extraordinary quantity of metallic chlorides, namely, 

 chloride of sodium with smaller quantities of the chlorides of 

 calcium and magnesium, and traces of protochloride of iron. 



On evaporating gastric juice we obtain a residue consisting of 

 crystals of chloride of sodium, moistened with a yellowish syrupy 

 mass, which consists principally of lactate of soda. The presence 

 of protochloride of iron may almost always be easily recognized in 

 strongly evaporated gastric juice by means of ferridcyanide of 

 potassium. 



Phosphate of lime is only present in small quantities in filtered 

 gastric juice. 



When the juice abounds in mucus or cells, this salt usually 

 occurs in larger quantities, if we estimate it by the ash left by the 

 residue. 



Alkaline sulphates and phosphates cannot be detected in pure 

 gastric juice ; neither can ammoniacal salts. 



For if ammonia were present, on evaporating fresh gastric juice 

 over hydrated magnesia, and extracting the residue with alcohol, 

 there would either be a development of ammonia (which is not 

 observed), or hydrochlorate and lactate of ammonia would be found 

 in the alcoholic solution ; on precipitating the bases from this 

 fluid with sulphuric acid, we find no trace of ammonia in the 

 deposit. If, however, the ammonia were combined with the mag- 

 nesia as triple phosphate, this might be readily discovered by a 

 microscopic examination of the residue insoluble in alcohol ; for 

 even when this residue was treated with a little phosphoric acid and 

 hydrochloric acid (perfectly free from ammonia), and the solution 

 digested with magnesia, the triple phosphate was not formed. 

 I can, therefore, only believe that the hydrochlorate of ammonia 

 found by Braconnot, Tiedemann and Gmelin, and others, must 

 have been formed during the chemical examination by the action 

 of free hydrochloric acid on mucus or some other nitrogenous 

 animal substance. 



In addition to the mineral constituents, we 'also find in the 

 gastric juice certain organic substances which, however, in con- 

 sequence of the extremely small quantities in which they occur, 

 have been very little examined ; these are a substance soluble in 

 water and in absolute alcohol (formerly known as osmazome), and 

 a substance soluble only in water, and more or less perfectly pre- 

 cipitable by alcohol, tannic acid, corrosive sublimate, and the salts 

 of lead; the latter, which seems to be a mixture of several 



