1838. HOUSE— No. 72. 23 



an acid is generated. But the formation of butter, or its separation 

 from the other elements of cream, does not depend on the absorption 

 of oxygen gas, as it can be obtained when the atmosphere is entirely 

 excluded. The curd which is formed, soon after the separation of 

 the cream, becomes a sort of coagulum, by the action of a free acid, 

 or by rennet. It is considered as pure caseous matter, or the basis 

 of cheese. The action of rennet, in separating the caseous matter, 

 is not well understood, but it is generally supposed to act in conse- 

 quence of the presence of gastric juice, which is always more or less 

 acid. 



Caseous matter yields, on analysis, carbon 59.78, hydrogen 7.42, 

 oxygen 11.40, nitrogen 21.38. When burnt, it yields an ash which 

 amounts to G.5 of its weight, the greater part of which is phosphate 

 of lime. This substance makes the caseous matter so valuable as an 

 article of food to young animals. It is during this period that the 

 bones require the deposition of this solid earthy matter to give them 

 strength and consistence. Milk, when deprived of cream, has a 

 specific gravity of 1.03, and yields, in the 1000 parts, water 

 928.75, caseous matter 28, sugar of milk 35, muriate and phosphate 

 of potassa 1.95, with traces of a few other unimportant elements. 



The following concise description of a few of the rarer animals of 

 this state, is offered in the room of a general catalogue. This course 

 appeared the most expedient, as two editions of the Geological Re- 

 })ort3 have been distributed in all the towns in the state, containing 

 catalogues of the animals nearly complete, and in which very few 

 additions or alterations can be made at the present time. 



1. Hystrix. 



.2.0 

 Generic Characters. Teeth. Incisors -^ , canines -q-, molars 



-|-. Total 20. 



H. dorsata, Gmelin. Porcupine. Color black. Feet armed 

 with long and moderately curved nails, 4 on the anterior, and 5 on 

 the posterior feet. Body and extremities covered with coarse hair, 



