598 FUNCTIONS OF ANIMALS. 



matters present appeared to be unnatural, and little capable of 

 being acted upon by the digestive organs. No traces of albu- 

 men could be found. 



The mackerel examined had just come from the coast where it 

 had been caught the day before. The stomach was nearly filled 

 with a whitish grumous mass, in which the undigested bony remains 

 of some small fish were visible. This mass very faintly reddened 

 litmus, and, by the assistance of heat, coagulated milk. It un- 

 derwent a partial coagulation by the acetic or other acids, espe- 

 cially when heat was applied ; but no traces of albumen could 

 be perceived in it. 



Physiologists seem to have been generally of opinion that the 

 stomach contained an uncombined acid, somehow connected with 

 the process of digestion, till Spallanzani concluded, from a great 

 number of experiments, that the gastric fluid, when in its natural 

 state, is neither acid nor alkaline. In the year 1823, Dr Prout 

 ascertained by numerous experiments that a free acid exists in 

 the stomach of the rabbit, the hare, the horse, the calf, and the 

 dog, and also in the liquid ejected from the human stomach in cases 

 of dyspepsia. He washed the contents of a rabbit's stomach with 

 distilled water, and divided the aqueous liquid into four equal 

 portions. The first was evaporated to dryness, and the residuum 

 incinerated. It was then redissolved, and the chlorine which it 

 contained was determined by means of nitrate of silver. The 

 second portion was supersaturated with potash, evaporated to dry- 

 ness, ignited, and its quantity of chlorine determined by nitrate 

 of silver. This gave the whole chlorine in the contents of the 

 stomach. The third portion was exactly neutralized by a solution 

 of potash of known strength. This gave the quantity of free 

 muriatic acid in the stomach. And from these data the quan- 

 tity of sal-ammoniac was calculated. The following table will 

 show the result of three experiments on the gastric juice of rab- 

 bits: 



No. 1. No. 2. No. a 



Grains. Grains. Grains. 



Muriatic acid combined with ~i 

 fixed alkali, . / 



Ditto with ammonia, . 1-56 0-76 0-40 



Ditto uncombined, . 1'59 2-22 2-72 



Total, 3-27 3-93 4-83 



